View meeting presentations abstracts below.
The Terrestrial Arctic 1
An Evaluation of Independent Science Supported by Arctic-GRO Data
The Arctic Great Rivers Observatory (Arctic-GRO) is an international effort to collect and analyze biogeochemical time-series data for the six largest Arctic rivers, which together drain two-thirds of the pan-Arctic watershed. The project began in 2002 as a contribution to the NSF-SEARCH Freshwater Integration Study and continues today as part of NSF’s Arctic Observing Network (AON). We have historically evaluated the scientific productivity of the project by considering the papers written by Arctic-GRO scientists. Here we take a different approach and investigate how scientists not affiliated with Arctic-GRO are using Arctic-GRO data, specifically searching for and then categorizing papers that use Arctic-GRO data for new analyses. We identified several dozen papers, most of which fall broadly into categories of ocean physics and biogeochemistry, watershed fluxes, or studies that reach beyond the Arctic domain. We will highlight several of these papers and summarize the ways in which different research communities are using Arctic-GRO data. We suggest that this approach will help us evaluate how well we are meeting NSF’s requirement that AON projects “contribute to the needs of the broader scientific community”. We further anticipate that the insights gained from this analysis will help guide our efforts to reach a larger and more diverse audience of potential data users and thus ultimately will make Arctic-GRO data more valuable for advancing understanding of Arctic system change.
Changing carbon balance and plant biomass at Imnavait Creek, Alaska
Understanding the magnitude of, and controls over, carbon fluxes in arctic ecosystems is essential for accurate assessment and prediction of their responses to climate change. Since 2008, we have monitored carbon, water and energy balance year-round by eddy covariance in three representative Alaska tundra ecosystems along a toposequence (a ridge site of heath tundra and moist non-acidic tunrdra, a mid-slope site of moist acidic tussock tundra, and a valley bottom site of wet sedge tundr and moist acidic tussock tundra) at Imnavait Creek, Alaska. In 2013, we harvested vegetation and soils in the most common plant community types in source areas for fluxes measured by these eddy covariance towers. All our sites have been annual net sources of CO2 to the atmosphere over eight years of measurement, but in the last two years, the valley bottom site has been a particularly strong source, due to CO2 losses in fall and winter that correspond with a longer period before the soil freezes fully. Aboveground biomass of vascular plants in moist acidic tundra at the mid-slope site was nearly three times higher than that measured thirty years earlier in vegetation harvests of nearby areas at Imnavait Creek. Other harvests from sites near Toolik Field Station suggest that vascular plant biomass in moist acidic tundra has increased in multiple sites over this time period. Increased biomass in the mid-1990s corresponds with a switch from mostly negative to mostly positive spatially-averaged air temperature anomalies in the climate record. Mobilization of soil C under the modest long-term warming that occurred in these ecosystems may have made available more soil N, leading to greater vascular plant productivity. Whether recent increases in C loss overwinter are sustainable over the longer term, and whether they will lead to further vegetation change, remains to be seen.
Drivers and Estimates of Terrain Suitability for Active Layer Detachment Slides and Retrogressive Thaw Slumps in the Brooks Range and Foothills of Northwest Alaska, USA
Active layer detachment sliding and retrogressive thaw slumping are important modes of upland permafrost degradation and disturbance in permafrost regions, and have been linked with climate warming trends, ecosystem impacts, and permafrost carbon release. In the Brooks Range and foothills of northwest Alaska, these features are widespread, with distribution linked to multiple landscape properties. Inter-related and co-varying terrain properties, including surficial geology, topography, geomorphology, vegetation and hydrology, are generally considered key drivers of permafrost landscape characteristics and responses to climate perturbation. However, these inter-relationships as collective drivers of terrain suitability for active layer detachment and retrogressive thaw slump processes are poorly understood in this region. We empirically tested and refined a hypothetical model of terrain factors driving active layer detachment and retrogressive thaw slump terrain suitability, and used final model results to generate synoptic terrain suitability estimates across the study region. Spatial data for terrain properties were examined against locations of 2,492 observed active layer detachments and 805 observed retrogressive thaw slumps using structural equation modelling and integrated terrain unit analysis. Factors significant to achieving model fit were found to substantially hone and constrain region-wide terrain suitability estimates, suggesting that omission of relevant factors leads to broad overestimation of terrain suitability. Resulting probabilistic maps of terrain suitability, and a threshold-delineated mask of suitable terrain, were used to quantify and describe landscape settings typical of these features. 51% of the study region is estimated suitable terrain for retrogressive thaw slumps, compared with 35% for active layer detachment slides, while 29% of the study region is estimated suitable for both. Results improve current understanding of arctic landscape vulnerability and responses to climate change, and enhance the capability to estimate quantities of permafrost carbon and nitrogen potentially subject to release through these modes of permafrost degradation.
Geomorphological controls on water and ecosystem processes in ice wedge polygon landscapes
A fundamental goal of the Next-Generation Ecosystem Experiments (NGEE-Arctic) project is to improve climate prediction through process understanding and representation of that knowledge in Earth System Models. Geomorphological units, including thaw lakes, drained thaw lake basins, and ice-rich polygonal ground provide the organizing framework for our scaling approach for the coastal plains of the North Slope of Alaska. Process studies and observations have been undertaken in and near the Barrow Environmental Observatory, BEO, across nested scales to understand and quantify the interactions between geomorphic landscape features, hydrology, soil temperature, biogeochemistry, vegetation patterns, and energy exchange in order to initialize and evaluate a suite of models within the NGEE hierarchical modeling framework. In-situ, ground based geophysical, airborne and satellite based observations are carried out across gradients of micro-topographic features (polygon rims, centers and troughs) and polygon types (high centered, low centered and transitional). Our studies are showing clear correlations between geomorphic features, and the dynamics of soil moisture, soil temperature and surface inundation patterns across the landscape, as well as soil biogeochemistry, vegetation patterns, and carbon and energy fluxes. Our data and findings are now being used to initialize and evaluate fine, intermediate and global scale models which are being used to simulate the evolution of a warming and thawing Arctic landscape and its feedbacks to the global climate system.
Integrating tower eddy covariance, satellite remote sensing and ecosystem modeling to identify changes in hydrology and carbon fluxes across the Alaskan Arctic
Terrestrial warming substantially impacts vegetation community dynamics, permafrost processes, hydrology and soil carbon (CO2, CH4) exchange across the Alaskan Arctic. Yet regional variability, long term trends and interacting effects in land-atmosphere energy, water, and carbon cycles are not well understood. Here we explore new information from tower eddy covariance measurement records along wetland tundra and permafrost gradients in northern Alaska. We link the tower data with strategic satellite observations including optical and microwave sensor retrievals of vegetation, surface water dynamics and freeze-thaw status, and regional carbon flux simulations from a satellite data driven Terrestrial Carbon Flux (TCF) model to examine contemporary net ecosystem carbon budgets for Arctic tundra, and shifts in CO2 to CH4 emission ratios within terrestrial ecosystems. The remote sensing records include 250 to 1000 m resolution vegetation indices from the Moderate-Resolution Imaging Spectroradiometer (MODIS) and coarser resolution (6 & 25 km) passive microwave daily surface freeze-thaw indices, vegetation optical depth and surface water inundation land parameters derived from Advanced Microwave Scanning Radiometer (AMSR) brightness temperatures to identify recent variability and trends in ecosystem productivity and underlying processes regulating terrestrial carbon cycle dynamics. These datasets indicate that Alaskan Arctic tundra communities remain in close balance between annual carbon inputs and net ecosystem carbon losses. The remote sensing records reveal a general lengthening of the annual non-frozen period across northern Alaska that may further heighten CO2 and CH4 emissions. We also find longer-term surface wetting patterns across Prudhoe Bay and the Arctic National Wildlife Refuge, in sharp contrast to surface drying and vegetation browning over the Seward Peninsula and western Alaska North Slope. The continued monitoring of land surface properties and carbon fluxes through remote sensing and tower eddy covariance observations is crucial to detect abrupt transitions in ecosystem function and to identify community vulnerability under a changing climate.
What role do glaciers play in subarctic hydrology?
Hydrological processes in glacier and permafrost affected landscapes are highly variable in time and space and subject to rapid transformation during a changing climate. In order to gain a deeper understanding of the linkages between glaciers, permafrost and hydrology on the watershed scale, a thorough measurement network was set up in the Jarvis Creek watershed (630 km2), which is a headwater basin of the Tanana River (12,000 km2), in semi-arid Interior Alaska. Runoff, glacier mass balance, end-of-winter snow depths, soil temperature, geochemistry, and meteorological variables (air temperature, precipitation, relative humidity, solar radiation, wind speed, snow depth) have been measured since 2011, to reflect an elevation gradient from north (lowland) to south (mountain).
We hypothesize that glacier melt i) maintains lowland streamflow during summer months and ii) recharges the regional aquifer. Glacier coverage of Jarvis basin (3% of total area) has been reduced by about 34 % (1950-2000), while providing up to 19 % (2014) to 58 % (2013) of total specific runoff in the lowland. The reduction in glacier area coincide with increased mean annual air temperature (+1.9°C) and summer warmth index (+6.5 °C), which is the sum of all mean monthly air temperature above 0 °C, since 1947 (Delta Junction). Change in annual, summer and winter precipitation has been negligible.
Our measurements also show that Jarvis Creek is a losing stream that recharges the regional aquifer. We postulate that the reduced glacier coverage, via increased aquifer recharge, is the primary cause of the observed increase in late winter baseflow of the Tanana River (+24 % 1974-2006, Fairbanks). These results suggest that glaciers do not only directly support streamflow in the headwater basins during summer months, but are also significant contributors to groundwater recharge in permafrost-free soils, thereby affecting the large scale hydrological regime of subarctic glacierized watersheds.
Arctic Atmosphere 1
A Radiation Closure Study of Arctic Cloud Microphysical Properties using the collocated satellite-surface data and Fu-Liou Radiative Transfer Model
Passive satellites often face difficulty when retrieving cloud microphysical properties over snow-covered surfaces. To quantitatively estimate their uncertainties, the CERES Ed4 retrieved single-layered overcast cloud microphysical properties have been compared with ground-based retrievals at the DOE ARM NSA site from March 2000 to December 2009. The ARM cloud properties were averaged over a 1-h interval centered at the time of each satellite overpass, and the CERES cloud properties were averaged within a 30 km x 30 km box centered on the ARM NSA site. These cloud microphysical properties, along with the ARM merged soundings and satellite observed O3 profile, are used as inputs for the NASA Langley modified Fu-Liou radiative transfer model (RTM) to calculate SW-down flux (and transmission, γ) at the surface and SW-up flux (and albedo, RTOA) at the top of atmosphere (TOA), and then compared with the collocated ARM surface and CERES TOA observations.
A total of 85 Terra and 156 Aqua single-layered overcast stratus cases under snow-free (surface albedo, Rsfc ≤ 0.3) and 62 Terra and 176 Aqua cases under snow (Rsfc > 0.3) conditions have been selected. For the snow-free cases, the CERES Ed4 retrieved cloud-droplet effective radius (re) is ~2.1 μm (16.4%) greater than the ARM mean (12.8 μm), and their optical depth (τ) and liquid water path (LWP) retrievals have an excellent agreement with the ARM results with high correlation of 0.78. For the snow cases, the CERES Ed4 and Ed2 retrieved re and τ are 4.6 μm (53%) greater and 3.2 (21%) lower than corresponding ARM results. Under both snow-free and snow conditions, the RTM calculated SW-down fluxes and SW transmissions with input of the ARM and CERES Ed4 cloud retrievals agree with ARM surface observations within 1 W m-2 and 0.01, respectively. However, the RTM calculated TOA SW_up fluxes are more than 20 Wm-2 and 50 Wm-2, respectively, more than the corresponding CERES observations for snow-free and snow conditions. Also the calculated TOA albedos are 0.04 and 0.08 higher than the CERES observations. Therefore, we conclude that the RTM calculations with input of the ARM and CERES cloud retrievals have better performance at the surface than at TOA, and have better radiation closure for snow-free cases than for snow cases. A sensitivity study has shown that both observed and calculated γ values decrease, but RTOA values increase with increasing τ and solar zenith angle.
Characterizing Arctic mixed-phase cloud and its relationship with humidity and temperature inversion using ARM NSA Observations
Arctic mixed-phase cloud (AMC) is the most frequently observed cloud type over the Arctic; its surprisingly long lifetime and complex interaction with environment make it difficult to be simulated in climate models. In this study, structure of the AMC as well as its interaction with the environment have been investigated using an integrated dataset collected at the ARM NSA site from October 2006 to September 2009. Two cloud-base heights (CBHs) are defined from ceilometer and micropulse lidar (MPL) measurements: the ceilometer-derived CBH represents base of the liquid-dominant layer near cloud top, while MPL-derived CBH represents base of the lower ice-dominant layer. The annual mean CBHs from ceilometer and MPL measurements are 1.0 km and 0.6 km, respectively, with the largest difference (~ 1.0 km) occurring from December to March and the smallest difference in September. Humidity inversions occurred ~70-90% of time over the Arctic, with the highest occurrence in summer. Summer is also dominated by strong humidity inversions: 70% of humidity inversions have intensities stronger than 0.5g/kg. During winter months, less than 40% of humidity inversions have intensity stronger than 0.3g/kg. On the other hand, during winter months, AMCs are more likely to occur with stronger humidity inversion: its occurrences increase from 15% to 35% when the inversion intensity increases from 0.1 to 0.9 g/kg. Despite the higher frequency of stronger humidity inversion in summer, AMC occurrences are nearly invariant for different inversion intensities. Moreover, both temperature and humidity inversions are 5-8 times more likely to exhibit above the AMC than below it. The strong inversion occurrences for both humidity and temperature above an AMC provide the moisture sources from above for the formation and maintenance of AMCs. This result helps to reconcile the persistency of AMCs even when the Arctic surface is covered by snow and ice.
Cloud statistics at Barrow, Alaska from a two-year infrared cloud imager deployment
The Infrared Cloud Imager (ICI) is a ground-based thermal imaging system that views the sky for measuring spatial and temporal patterns of cloud presence and cloud optical depth. An ICI system was deployed at Barrow, Alaska from August 2012 to August 2014 and recorded cloud distributions continuously with equal sensitivity in both day and night. This diurnal consistency creates a huge advantage for the ICI method over visible cloud imaging, which typically rely on entirely different detection algorithms during day and night. The upward-looking geometry also provides a significant advantage over satellites, which struggle with low radiometric contrast between the clouds and underlying snow-covered surfaces in either short-wave or long-wave imaging bands. Preliminary analysis of the data from this two-year deployment indicate that the frequent presence of thin clouds that are not detected by other sensors that measure or infer cloud fraction at the Atmospheric Radiation Measurement (ARM) facility at Barrow. In fact, by filtering our data to count only clouds with optical depth of 1.0 or higher produces excellent correlation (greater than 90%) with other ARM measurements of cloud fraction. Adding in clouds that the ICI detects with an inferred optical depth between 0.25 and 1.0 reduces the correlation with the other instruments greatly and reveals a much higher frequency of occurrence for these thin clouds. This presentation will summarize the ICI measurement method and introduce its data to the community in the interest of identifying collaborative use of our measurements.
Observationally Closing the Arctic Atmosphere-Surface Energy Balance
Understanding how heat and energy are exchanged between the atmosphere and the underlying surface is a critical step towards determining the processes controlling the changing distributions of Arctic permafrost, snow and ice. It is therefore not surprising that the common research objective to understand these exchanges has led to the installation of instruments to measure the components of the surface energy balance at a number of the IASOA (International Arctic Systems for Observing the atmosphere) observatories. The measurements suites include co-located micro-meteorological flux towers to measure turbulence and gas fluxes, suites of broad-band radiometers to measure radiative fluxes and soil temperature and moisture sensors to measure ground heat fluxes.
Measurement and calculation of the separate components of the energy balance equation presents special challenges in the Arctic environment including riming of instruments, unstable instrument performance at extremely cold temperatures, lack of operator access during extreme weather events, the extreme inhomogeneity of the active layer and complications introduced by snow, ice and vegetation covered surfaces.
For a 20 m tower located at the observatory in Tiksi, Russia and a 10 m tower at the observatory in Eureka, Canada considerable effort has been made to produce a multiyear data product that is composed of 1-hourly averages of all components of the surface energy balance as well as relevant meteorological quantities. This data product is being used to determine if it possible to reduce measurement errors and uncertainties so that it is possible to observationally close the surface energy balance for Arctic locations. Preliminary results suggest that there is significant variability between adjacent locations at a single site due to soil and surface inhomogeneity. This result suggests that it will be necessary to develop a locally distributed measurement strategy to account for local variations before measurements can be meaningfully compared between geographically separated sites to assess regional variability.
Surface radiation budget and cloud radiative effects from pan-Arctic Baseline Surface Radiation Network (BSRN) stations
Monitoring and forecasting seasonal melting of snow and ice in the Arctic, which represents the largest annual perturbation to the surface net radiation budget, is a priority need as the Arctic climate changes and the number of stakeholders increases. Cloud-surface-atmosphere radiative interactions play an important role on scales of minutes to decades, but models insufficiently represent cloud properties, and the surface energy budget is not directly observed from satellite platforms. Direct observations offer the best means to document physical and correlative relationships between variables, and to provide a baseline target for data sets with more comprehensive spatial representation.
High-quality, continuous, long-term observations of radiative fluxes are collected from land stations surrounding the Arctic Basin as part of the Baseline Surface Radiation Network (BSRN). The International Arctic Systems for Observing the Atmosphere (IASOA) facilitates international collaboration amongst station scientists and other topic experts for the purposes of streamlining pan-Arctic synthesis studies. The IASOA Radiation Working Group is currently analyzing the data acquired from Barrow, Alaska (1993-2015), Alert, Canada (2004-2014), Ny-Ålesund, Svalbard (1993-2015), Eureka, Canada (2007-2015), and Tiksi, Russia (2011-2015). The measurements include upwelling and downwelling longwave and shortwave fluxes, as well as direct and diffuse shortwave flux components, and surface meteorology. The observations are post-processed using the Radiative Flux Analysis (RadFlux) method, which, in addition to basic quality control, provides value-added metrics such as cloud radiative effects (CRE), optical depth, and fractional sky cover. Here, we present a spatial and temporal analysis of the surface radiation budget and calculated variables from the pan-Arctic BSRN stations. Particular attention is given to inter-site variability of seasonal cycles in CRE and associated relationships with surface albedo and cloud macrophysics.
The impact of Arctic liquid water clouds on surface and sub-surface fluxes
The surface energy budget over Arctic terrestrial surfaces largely controls the state of soil temperatures and permafrost below. Atmospheric drivers are primarily responsible for variability in the surface energy budget, with one of the strongest contributors being clouds. In recent years, Arctic stratiform, liquid-containing clouds have been shown to form and persist over long periods via a complex web of interactions and feedbacks within the climate system. Moreover, these clouds are known to have particularly strong interactions with atmospheric radiation that can elicit other energetic responses in the atmosphere-surface system. This presentation examines the specific role that liquid water clouds at Barrow, Alaska play in determining the local surface energy budget and sub-surface heat fluxes. Ground-based sensors are used to derive the surface radiative, turbulent, and sub-surface heat fluxes. Clouds are identified using a combination of active and passive remote sensors at the surface, while liquid water clouds are identified using microwave radiometer retrievals. The cloud forcing for each energy flux term is examined by comparing the flux at times when liquid clouds are present versus times when they are not, while scaling by the fractional occurrence of liquid clouds. Annual cycle statistics reveal seasonally varying responses to cloud radiative forcing that are dependent on factors such as the solar input, snow on the surface, and soil temperature.
Ultraviolet radiation in the Arctic: an update
After the discovery of the ozone hole in 1985, Biospherical Instruments was selected by the NSF to establish a network for measuring solar ultraviolet (UV) and visible radiation at high latitudes (Arctic and Antarctic). Observations at Barrow, Alaska, and Summit, Greenland, have been supported by two NSF AON grants, resulting in continuous Climate Data Records, starting in 1991 at Barrow and 2004 at Summit. More than 1000 researchers and students have used network data over the years, working in fields ranging from atmospheric studies to research into UV effects on terrestrial and aquatic ecosystems as well as humans. Measurements from the two sites have also recently been used to validate surface UV radiation data from the Ozone Monitoring Instrument (OMI) on NASA’s Aura satellite. This research revealed large systematic errors in UV radiation estimates from space because of the difficulty of satellite sensors to distinguish between snow and clouds. Measurements at Summit were found to be ideally suited to detect temporal drifts in satellite data records. Analysis of the 20+ year data record at Barrow uncovered a large negative trend for October, which was attributed to changes in the onset of snow cover during fall, highlighting the importance of climatic factors on the Arctic UV radiation environment. Secondary data products of the project include total ozone, surface albedo, cloud optical depth, and photolysis rates for air chemistry studies. This presentation introduces two new data products that have recently been developed: the retrieval of the vertical distribution of ozone in the atmosphere from measurements of the spectroradiometer at Summit and the assessment of the UV radiation environment and Barrow and Summit in terms of its ability to produce Vitamin D upon absorption in human skin. These new data products will be of interest to the atmospheric research and UV effects communities.
An Interoperable System for Sharing the Results of Community Based Monitoring
The Exchange for Local Observations and Knowledge of the Arctic's (ELOKA) mission is to provide data management and user support services to facilitate the collection, exchange, use and preservation of local observations and knowledge of the Arctic. Over the course of our projects, we have worked with partners to develop a modular, component-based system that is designed to enable cross-disciplinary research in physical and social sciences. The system is being leveraged to enable data access through easy to use interfaces as well as supporting interoperable data exchange and long-term archiving.
End users can explore data using a variety of interactive, multimodal tools. Interactive maps allow users to visualize geographic data while at the same time linking to associated multimedia that provides an extended view and understanding of space and place. Spatiotemporal display is supported providing the ability to recognize change over time. Multimedia representation is used to allow residents of the Arctic to share knowledge through narrative in their own language (i.e. Inuktitut), while concurrent translations enable others in broadening their understanding. Through collaborative research, advanced visualization tools connect knowledge domains through semantic modelking and linked data.
Underlying the technical systems is a network of community members, Indigenous organizations, and researchers who are working together to understand how to develop interoperable systems in a way that respects community priorities. These activities are resulting in an emerging set of standards and specifications that will be broadly useful to others engaged in community based monitoring and other community-driven research.
Best Practices for Community-based Observing Networks and Systems (CBONS) – standards, quality assurance, protections and data interoperability
Community-based systems are critical to the detection and observation of change in the Arctic, to defining thresholds, to devising responses to changing environments and critical events, and to informing adaptation decision-making. Community-based monitoring (CBM) generally, and community-based observing networks and systems (CBONS) specifically, offer robust frameworks for the placement of observations of change in a social context. This paper explores a typology of CBM efforts, including CBONS, citizen science, and observer blogs and explores their characteristics and the multiple roles they play in Arctic observing and adaptation. We propose an initiative for establishing and maintaining a set of best practices to support community-based observing networks and systems. This would include community network protocols, data standards, quality assurance, community and knowledge protections, and data interoperability. We outline an initiative and progress toward establishing a collaboration network for sharing best practices across Arctic communities and for extending lessons learned beyond the Arctic.
Citizen Science at the North Pole: Tourists as a Data Resource
Between June and August every year, the world’s largest and most powerful icebreaker, 50 let Pobedy, journeys to the Geographic North Pole 6-8 times carrying paying passengers, spending 3-5 days breaking sea ice during each voyage. With the ship traversing the same approximate meridian each time, during a period that covers the main summer melt and the beginning of the winter freeze, the opportunities for data collection are clear. As well as the obvious benefits of utilizing a tourism cruise for scientific purposes, it is an excellent opportunity for education and involvement of the guests on board.
With this in mind, expedition photographer Lauren Farmer and geologist Alex Cowan, employed as cruise staff on board 50 let Pobedy by Poseidon Expeditions, facilitated a citizen science program to collect this sea ice data, both from the bridge of the ship, from helicopters and on the ice at the North Pole.
Along with 36 enthusiastic guests ranging in age from 8 to 75, they recorded sea ice thickness, type and extent data, as well as melt pond distribution, depth and salinity for the International Arctic Research Center at the University of Alaska Fairbanks, McGill University and the U.S. Army Corps of Engineers ERDC Cold Regions Research and Engineering Laboratory.
Dozens of expedition cruise vessels traverse some of the more remote parts of the ocean year round. By taking into consideration the way in which they operate, research scientists and cruise staff should be able to collaborate to collect useful data while also fulfilling the chief aims of a tourism trip, to the benefit of both the operator and to researchers. In this presentation, Lauren and Alex hope to alert the polar science community to the existence of this underutilized resource and also provide guidance on how to take advantage of it.
Historical Ecology for Risk Management: Youth Sustainability for Coastal Observers of Barrow
Applied Research in Environmental Sciences Nonprofit, Inc., North Slope Borough Risk Management, Tuzzy Consortium Library, UIC Science Cultural Resources Management, Cooperative Extension of Ilisagvik Community College, and the North Slope Borough School District Instructional Coordination collaborated to implement a historical ecology (HE) model for the North Slope Coastal Region of Alaska.
HE is an applied research program about interactions of people and their environments in both time and space to study its long term effects. Research can be applied to community landscapes to assist management strategies including environmental conservation, ecosystem services, and hazard mitigation.
HE aligns with the ARIES mission of research, education, and community engagement such as the Inupiaq Learning Framework (ILF) for risk reduction based on the eco-heritage indicator of the CRIOS model about multiple jurisdictional cooperation of tribal inclusive geographic areas (www.ariesnonprofit.com/ARIESprojects.php). HE and ILF align since traditional knowledge recognizes complexity of Social-ecological Systems.
The current HERMYS project emphases are:
1. Compile a bibliographic database of historical resources of both social and natural sciences relevant to risk and disaster management, 2. Conduct a historical examination of the shoreline for a time-series baseline using historical records/maps along with geo-referenced historical imagery, 3. Develop simulation models to demonstrate socio-natural cycles of change for the North Slope shorelines for mitigation with Risk Management, 4. Study HE of the shoreline with interactive mapping to assist web based databases for academia, industry, regional government, disaster risk reduction, and local communities for socio-cultural and environmental management (e.g., BAID, ShoreZone), 5. Integrate a team of trans-disciplinary researchers, industry, community planners, risk management, Native corporations to assist community decision making, research participation, risk educational products, and community service learning, especially Community Based Beach Monitoring of Coastal Infrastructure (fb @COBCBM, Coastal Observers of Barrow) to include PolarTREC and fb @North Slope Teen CERT.
Tracking the state and use of coastal ice in Alaska communities through collaborative observations
The Seasonal Ice Zone Observing Network (SIZONet) has been studying the changing state and uses of coastal sea ice in several Alaska and Chukotka communities since 2006, initially under the IPY 2007–2008 program. Inupiaq and Yupik ice experts have contributed daily and monthly logs of ice and environmental conditions and helped guide development of a database to collect and share this information. The emphasis has been on tracking key variables through observations rooted in local ice uses and traditional knowledge, combining these efforts with geophysical measurements. The latter focused on processes relevant for the ice mass budget, its seasonal cycle and long-term transformation and evolving uses by people and animals.
Work at Barrow revealed a trend towards reduced shorefast ice stability and more dynamic interaction between sea ice and the shoreline, which in turn was reflected in the routing of ice trails and adaptation of ice use practices. Lower landfast ice stability in northern Alaska is due to reductions in multiyear ice extent and destabilization by strong currents and winter bottom melt. Around Bering Strait, observers report delayed freeze-up and winter ice formation, often by several weeks, and a less predictable break-up period increasing risk and safety concerns during spring subsistence whaling and walrus hunting.
The observations also showed major shifts and regional contrasts in key seasonal ice cycle events. The potential value of such observations in identifying coastal hazards and threats, in particular during the fall and spring transition seasons has been explored jointly with the Alaska Native Tribal Health Consortium and informed the development of a freeze-up observation protocol. The observations and further input have also guided siting and analysis of under-ice current, ice thickness and ice radar measurements. The latter in particular lends itself to hybrid observatory approaches of potential greatest value for all partners.
The Terrestrial Arctic 2
Circumpolar Active Layer Monitoring (CALM) program: long-term monitoring of the active layer/upper permafrost system.
The Circumpolar Active Layer Monitoring network, comprised of more than 200 sites, represents the only coordinated and standardized program of observations designed to observe and detect decadal changes in the dynamics of seasonal thawing in high-latitude soils. It provides long-term time series of active layer thickness, ground temperature, and thaw settlement measurements at the same locations and across diverse terrain types and regions to establish trends and validate models. In this study we report long-term active layer trends for characteristic regions of the circumpolar Arctic, with specific emphasis on northern Alaska. We used data from 21 (1995-2015) years of extensive, spatially oriented field observations at Alaskan CALM sites to examine landscape-specific temporal and spatial ALT variability and its relation to climatic forcing and heterogeneity of edaphic properties. Soil consolidation accompanying penetration of thaw into an ice-rich stratum at the base of the active layer may obscure active-layer measurements, resulting in underrepresentation of the overall response of the active layer- upper permafrost system to climatic forcing. Here we provide results of long-term simultaneous monitoring of elevational position of the ground surface and thaw depth at representative Alaska landscapes to evaluate the impact of surface heave and subsidence on traditional active-layer observations.
Development of a Permafrost Observing Network in Alaska and Russia
The impact of climate warming on permafrost and the potential of climate feedbacks resulting from permafrost thawing have recently received a great deal of attention. Ground temperatures are a primary indicator of permafrost stability. The monitoring network of the Thermal State of Permafrost (TSP) program established during the Fourth International Polar Year has more than 600 sites across the Arctic. In Alaska, two major permafrost temperature measurement networks exist. One of them is operated by the U. S. Geological Survey predominantly within the North Slope of Alaska. The second network was established in the late-1970s and early-1980 by Professor Emeritus T. E. Osterkamp and has been supported since then by the Permafrost group at the Geophysical Institute University of Alaska Fairbanks. Most of the research sites of this network are located along an Alaskan Permafrost-Ecological Transect. This transect spans all permafrost zones in Alaska from the southern limits of permafrost near Glennalen to the Arctic coast in the Prudhoe Bay region. Most of the long records of permafrost temperature in Russia come from several regions of intensive industrial development and from the long-term scientific research stations. Data from about 150 monitoring boreholes in Russia with various lengths of records are available now for the international permafrost community. In this presentation the results of more than 30 years of the permafrost and active layer temperature observations in Alaska and Russia will be presented. Most of the permafrost observatories in Alaska and Russia show substantial warming of permafrost since 1980s. The magnitude of warming has varied with location, but was typically from 0.5 to 2°C. However, this warming was not linear in time and not spatially uniform. General warming trend in permafrost temperatures triggered permafrost degradation in Alaska and Russia, especially at the locations affected by human activities.
Geochemical and Isotopic Characterization from the Polygonal to Landscape Scale in an Arctic Ecosystem
One of the goals of the DOE Next Generation Ecosystem Experiment (NGEE) Arctic project is to understand the significance of lateral & vertical variations in hydrology & biogeochemical cycling from the fine (i.e., polygon) scale to the larger landscape scale. Understanding these variations is critical to predicting carbon, nitrogen, and water balances of tundra ecosystems & helps inform models of Arctic ecosystem processes, & how Arctic ecosystems may respond to projected climate change and landscape evolution. This presentation presents an overview of results from Barrow, Alaska and includes both polygon- & landscape-scale perspectives. Our results indicate that summer rain is the dominant source for active layer groundwater, with melting seasonal ice contributing to deeper pore waters in late summer. Microtopography and water table effects significantly affected the concentrations of cations and anions for Polygon “Types” (High- versus Low- Centered Polygons), microtopographic features “Features” (Center versus Trough), and with Depth. Results have implications for future nutrient availability with projected permafrost degradation and landscape evolution, suggesting greater availability of limiting nutrients (sulfate, phosphate, and nitrate) where polygons undergo a shift from low- to high-centered. Nitrate isotopes (δ15N and δ18O) indicated a predominantly microbial source for nitrate in high centered polygons active layers. Additionally, results suggest that older, deeper C sources may be promoting a shift in methanogenic pathway, from predominantly acetoclastic to hydrogenotrophic. This mechanistic shift is attributed to the source and quality of available organic substrate. Overall, results showed substantial lateral and vertical variability in biogeochemical, biogeophysical, and hydrological processes across microtopographic- to landscape scales to complement remotely sensed measurements, and needs to be accounted for in fine and intermediate scale models.
High and Low Arctic Changes in Biogeochemical and Ecohydrologic Processes
We have undertaken measurements of trace gas and ecohydrologic process in N Alaska and in NW Greenland as part of AON-ITEX and our AON-EAGER program. Our program provides quantitative estimates of trace gas exchanges, shifts in vegetation and mechanisms of change as the Arctic undergoes coupled shifts in precipitation (snow) and temperature (warmer summers) based on a 20 year field experiment. In addition, our studies have revealed an ability to monitor in real-time the Arctic Ocean off the coast of Alaska and it's sea ice properties with land-based water vapor isotope measurements and to measure switching moisture sources between the Greenland Ice Sheet and Baffin Bay at our coastal site in NW Greenland. We have used a suite of technologies that allow observations across a range of scales from leaf-level physiology, to ecosystem-scale CO2 fluxes, along with the use of aircraft to characterize landscape-scale ecohydrological properties. Our program is now positioned to undertake a new phase of Arctic change research including a Western Arctic Network from Barrow to Svalbard addressing moisture sources and synoptic climatology associated with sea ice properties along with ITEX tundra-based studies of trace gas feedbacks and vegetation change.
Long-term hydrological and ecological observations along the eastern Beaufort Sea coast of Alaska: Linkages to regional climate and subsistence
Along the US-Arctic Beaufort Sea coast, over 50% of the shoreline is fringed by barrier islands which enclose numerous bays and lagoons which are refugia for numerous species, including migratory fish and waterfowl that are essential to the subsistence and culture of Iñupiat communities of northern Alaska. In the eastern Beaufort, in particular, residents of Kaktovik rely heavily on the high benthic productivity of these lagoon systems to support the fish and bird populations that they depend on for subsistence. Over the past several years we have established and maintained a suite of observing activities that are indicative of ecosystem status in lagoons that span the Alaskan Beaufort Sea coast, from Stefansson Sound to Demarcation Bay. Our hydrographic data revealed that lagoons possess unique hydrologic and geomorphic characteristics that vary seasonally as reflected by continuous in situ measurements of temperature and salinity. H2O-δ18O and salinity measurements revealed meteoric water is the dominant source of low-salinity water in all lagoons in June and August and most differences among lagoons were caused by variation in freshwater input, rather than differences in circulation. We also used stable isotopic tracers to examine trophic pathways and assess dependence of these fauna on terrestrial (CT) vs. marine sources of carbon, with particular focus on animals widely used by local subsistence hunters. Our mixing model suggests that upper trophic level consumers assimilate substantial amounts of terrestrial (CT) carbon along with marine-derived C sources. For example, 50 - 70% of polar bear and 30 - 50% of beluga whale carbon was of terrestrial origin. Our results suggest that 1) CT assimilated by benthic omnivorous invertebrates is transferred to the highest trophic levels in the Beaufort Sea, and 2) arctic cod are the most likely intermediary for transferring CT from lower to upper trophic levels.
Plot to landscape scale phenology near Barrow and Atqasuk : 2010-2015… A contribution to the US Arctic Observing Network
The need to improve the spatial and temporal scaling and extrapolation of plot level ecosystem properties and processes to the landscape level remains a persistent research challenge in the Arctic. Plant and landscape phenology is sensitive to a number of spatiotemporally variable environmental factors such as soil moisture, temperature, and radiation. Seasonal and inter-annual differences in phenology can affect surface energy balance and land-atmosphere carbon flux. Considering the relative importance of the Arctic to global carbon balance, improved scaling and extrapolation of phenological dynamics from the plot level to the landscape level is important for advancing our understanding of the impact of climate and other environmental change in arctic terrestrial ecosystems.
Here we present plot to landscape scale phenological dynamics for sites established near Barrow and Atqasuk in northern Alaska between 2010 and 2015. This study contributes to the NSF-Arctic Observing Network and the International Tundra Experiment. Plot, community and landscape phenology are measured with hyperspectral reflectance and digital photography, phenocam, and kite aerial photography respectively. Gridded study areas are also sampled with terrestrial LiDAR each year to document fine-scale vertical change in response to freeze-thaw dynamics. Analysis has included the development of novel software for data processing and analysis. For all land cover types, seasonal greenup was advanced in Atqasuk relative to Barrow and in warm years relative to cold years. Greenup was also greater and more variable between years for wet land cover types relative to dry land cover types. These results are being used to disentangle the complexity of regional-scale satellite-derived greening occurring in the area.
Stitching Water: Building Collaborative Monitoring Networks in Alaska
Alaska Landscape Conservation Cooperatives (LCCs) share a common objective to promote enhanced understanding of the drivers of ecosystem change, on regional to landscape scales. Water-related variables are high priority monitoring targets, however, the high cost of collecting data in Alaska places a premium on efficiency, collaboration and data sharing. LCC-led efforts to promote collaborative freshwater monitoring networks must address these challenges.
At the Western Alaska LCC, we have engaged in a deliberate sequence of activities to establish a voluntary, statewide freshwater temperature monitoring network, including an inventory of historical and contemporary data records, establishing of data-collection standards, implementing observations on a pilot basis, and conducting “proof-of-concept” analyses that allow us to explore applications for the resulting projections of change. One of our important goals was to facilitate community-based and citizen-science participation in this monitoring network.
At the Arctic LCC, we are establishing the Terrestrial Environmental Observation Network (TEON), a long-term monitoring program for key drivers of ecosystem change. The TEON spatial framework, based on sampling representative focal watersheds, emphasizes the importance placed on hydrological processes. TEON collects complementary times-series for variables related to climate, surface water, soils, permafrost and vegetation, incorporating sites and methods from existing observing programs to the extent possible. Design activities included inventory of existing data records, selection of key variables, data collection protocols, and database design. We have also developed Imiq, a statewide portal for hydroclimate data. Imiq aggregates and exports data records from multiple sources in a common format, with full metadata records that provide information about the source data.
Many of the issues encountered in these parallel efforts were similar, and are being addressed effectively. Our greatest challenge is to overcome institutional barriers to sustained funding for collaborative efforts that serve multiple end-users, but are not clearly the responsibility of any one entity.
The NASA Arctic-Boreal Vulnerability Experiment
The Arctic-Boreal Vulnerability Experiment (ABoVE), a field campaign sponsored and initiated by NASA’s Terrestrial Ecology Program, is a large-scale study of changes to terrestrial and freshwater ecosystems in the Arctic and boreal regions of western North America and the implications of these changes for local, regional, and global social-ecological systems. The overarching question of ABoVE is “How vulnerable or resilient are ecosystems and society to environmental change in the Arctic and boreal region of western North America?” To address this question, research is being conducted in six thematic areas which represent critical aspects of Arctic and boreal social-ecological systems: society, disturbance, permafrost, hydrology, flora/fauna, and carbon biogeochemistry. Throughout the 8 to 10 year campaign, research will integrate field-based studies, modeling, and data from airborne and satellite remote sensing. There are currently 39 projects contributing to ABoVE through research in one or more of the six themes described above, including 21 core research projects recently funded by NASA specifically to address the ABoVE objectives. Field work will commence in 2016, with an airborne science campaign to follow in subsequent years. In an effort to accelerate the pace of new Arctic science for researchers participating in the field campaign, infrastructure and logistics support, including high performance science cloud computing, is provided for scientists participating in ABoVE. Here we provide an update on the current status and future prospects for arctic observations and research conducted as part of ABoVE.
What’s New in the Arctic Coastal Zone?
Recent Arctic warming has resulted in pronounced change in key terrestrial and the coastal controls. However, the ramifications of these changes for the coupled land-ocean system remain still largely unknown or unquantified, especially at the regional to local scale. River discharge has increased by ~10% for the major Siberian Rivers, as well as the Mackenzie and Yukon Rivers. The timing of the delivery of the spring snowmelt pulse has shifted. In addition, changes in iceberg, freshwater and sediment flux occur along Greenland. Our community has only begun to map and model the effects of this additional freshwater, heat, and nutrient fluxes to the Arctic Ocean. Coastal processes have accelerated over the last decades; sea ice limits the physical vulnerability of Arctic coasts to erosion and inundation by ocean storms. Now that the duration of sea-ice free conditions has increased 1,5 to 3 fold Arctic-wide, exposure of the coastal system, and the native communities and infrastructure, to storms has dramatically lengthened. Warming ocean water is another factor that causes large sections of the coast to be eroding at 1-3m/year, with most dramatic erosion rates of 17m/year found along the permafrost bluffs of the Beaufort Sea. Estimates of the resulting release of terrestrial organic carbon stored in ice-rich permafrost point at a significant new source of carbon into the Arctic coastal zone. Coastal geomorphological models indicate strong sensitivity to future sea level and cyclone activity, and thus pose a research agenda to improve predictions. Analysis of the sea ice evolution from the Community Earth System Model-Large Ensemble shows that under a ‘business-as-usual’ scenario (RCP8.5), ice will cover the coastal zone for only half of the year by 2070. The ramifications of such projected expansion are likely pronounced and call for a better understanding of the integrated human and physical-biological system.
Arctic Atmosphere 2
A comprehensive climatology of Arctic aerosol properties on the North Slope of Alaska
Aerosol properties have implications for the formation of Arctic clouds, resulting in impacts on cloud lifetime, precipitation processes, and radiative forcing. There are many remaining uncertainties and large discrepancies regarding modeled and observed Arctic aerosol properties, illustrating the need for more detailed observations to improve simulations of Arctic aerosol and more generally, projections of the components of the aerosol-driven processes that impact sea ice loss/gain. In particular, the sources and climatic effects of Arctic aerosol particles are severely understudied. Here, we present a comprehensive, long-term record of aerosol observations from the North Slope of Alaska baseline site at Barrow. These measurements include sub- and supermicron (up to 10 µm) total mass concentrations, sub- and supermicron soluble inorganic and organic ion concentrations, submicron metal concentrations, submicron particle size distributions, sub- and supermicron absorption and scattering properties, and aerosol optical depth. Aerosol scattering measurements extend back to 1976, while the remaining measurements were implemented since. Corroboration between the chemistry, size, and optical property measurements is evident during periods of overlapping observations, demonstrating the reliability of the measurements. During the Arctic Haze in the winter/spring, high concentrations of submicron sea salt, mineral dust, industrial metals, pollution (non-sea salt sulfate, nitrate, ammonium), and biomass burning species are observed concurrent with higher concentrations of particles with sizes that span the submicron range, enhanced absorption and scattering coefficients, and largest Ångström exponents. The summer is characterized by high concentrations of biogenic aerosol species, small particle sizes (< 100 µm), and low extinction coefficients. Fall is characterized by clean conditions, with supermicron sea salt representing the dominant aerosol type supporting the highest single scattering albedos. This complete set of aerosol properties can be used to improve our knowledge of the sources of aerosols found in the Arctic.
A Mechanism Linking Tropical-Arctic Teleconnection to Northern Hemisphere Mid-Latitude Weather Events
Several lines of research have suggested linkages between Arctic sea-ice loss and the Northern Hemisphere (NH) mid- and high-latitude circulation changes. These studies have collectively suggested various mechanisms in which sea-ice loss is an active modulator of NH mid-latitude large-scale circulation, weather, and extreme events. This is an area of vigorous scientific debate, and a consensus has not emerged; competing hypotheses clearly need to be examined. To contribute to this debate, we propose a new mechanism to explain the observed concurrence of the NH circulation trends and sea-ice loss in the past 30 years. Our mechanism is based on lines of evidence suggesting that the recent summer NH circulation trend in and around the Arctic is both natural and anthropogenic in origin, but natural variability originating primarily from the tropics plays a dominant role in generating the observed circulation pattern—especially the increasing height over Greenland and northeastern Canada—which may play a key role in modulating Arctic sea-ice change and the mid-latitude weather and extreme events over North America at the same time.
Application of measurements of atmospheric O2 and CO2 for detection of long-term changes in the Arctic
Measurements of atmospheric CO2 and O2 concentration are now being made in the Arctic by several programs, including Scripps O2 and CO2 programs, which pioneered these measurements. While the main focus of these programs is global, their Arctic components can form the backbone of a proto observing system for detecting wide-spread changes in the Arctic in the decades ahead. Atmospheric measurements are especially powerful for detection of large-scale secular change, taking advantage of atmospheric mixing as an integrator. Major questions regarding the evolution of Arctic biogeochemistry could potentially be addressed with a tailored O2 and CO2 observing system, including the magnitude of carbon sources and sinks, and rate of change of biogeochemical functioning of ocean and land masses, thus complementing in situ or remote sensing methods. This presentation will focus on the following questions: How well can the existing network(s) resolve fluxes specific to the Arctic? How large are the atmospheric signals expected from changes in Arctic biogeochemistry over the next decades? How much greater resolving power would be possible with higher density in O2 and CO2 measurements?
O2 and CO2 measurements provide cross cutting constraints. On seasonal and shorter time scales, the dominant source of variability in CO2 is photosynthesis and respiration of terrestrial ecosystems, which also influence O2. On these time scales, O2 is however also strongly influenced by air-sea O2 exchanges. This oceanic O2 signal can be isolated via the tracer "atmospheric potential oxygen" = O2+1.1CO2, which cancels the land signals but not the residual oceanic O2 signal. Combined measurements of O2 and CO2 thus separately constrain land exchanges of CO2 and oceanic exchanges of O2.
Autonomous "OBuoy" observations of the Arctic atmosphere
As a part of a NSF Arctic Observing Network project, fifteen (15) autonomous ice-tethered "Obuoys" have been deployed to measure three sentinel atmospheric chemicals, carbon dioxide, ozone, and reactive halogens over the past five years. The Obuoys were co-deployed with snow/ice measurement systems (e.g. Ice Mass Balance buoys) and oceanographic measurements (e.g. Ice Tethered Profilers) to develop an integrated picture of the coupled ocean/ice/atmosphere system. Reactive halogens are produced photochemically from salts in sea ice during Arctic springtime and are potent oxidizers that cause mercury deposition to snowpack and remove ozone from the boundary layer. Observations from the reactive halogen instrument demonstrate that boundary layer structures (e.g. inversion layer depth) are a major control on the amount of halogen activation. A future Arctic situation with more open leads would be expected to have greater vertical mixing and thus more halogen activation, increasing the atmospheric oxidation capacity. One known consequence of this enhanced halogen oxidation is that more mercury would be oxidized and deposited to snowpack. Other consequences of increased oxidation capacity are less known but likely important to a future Arctic climate. For example, oxidation processes create new particles from gases (such as dimethyl sulfide is oxidized to sulfate aerosol) and oxidation of particles modifies their ability to interact with water, altering cloud/ice condensing nuclei activity. Future work directed at understanding how these photoxidants affect CCN/IN properties is critical for understanding future Arctic clouds and climate in a reduced summer sea ice scenario where atmospheric photooxidation processes would be expected to be altered.
Climatology and Characteristics of Aerosol Optical Properties in the Arctic
Within the Arctic, climate forcers like atmospheric aerosols are important contributors to the observed warming and environmental changes in the region. Quantifying the forcing by aerosols in the Arctic is especially difficult, given short aerosol lifetimes, annual variability in illumination and surface albedo, stratified atmospheric conditions, complex feedbacks, and long-range aerosol transport. However, in-situ surface measurements of Arctic aerosol optical properties can be used to constrain variability of light scattering and absorption, identify potential particle sources, and help evaluate the resulting forcing. Data from six WMO Global Atmosphere Watch stations are presented: Alert, Canada (ALT); Barrow, Alaska (BRW); Pallas, Finland (PAL); Summit, Greenland (SUM); Tiksi, Russia (TIK); and Zeppelin Mountain, Norway (ZEP). These sites contribute to the International Arctic System for Observing the Atmosphere (IASOA), which facilitates Arctic-wide data collection and analysis. Climatologies of aerosol optical properties from each station show differences in magnitude and variability of observed parameters. For example, Figure 1 presents the annual cycle of aerosol light scattering at 550 nm at each site for 2012-2014, with most stations (ALT, BRW, SUM, TIK, ZEP) experiencing maximum scattering in winter/spring, while PAL exhibits maximum scattering in the summer. The observed range in scattering across these sites is large (almost an order of magnitude) - SUM has the lowest annual median scattering at 0.82 Mm-1 while BRW has the highest at 6.9 Mm-1. A closer look at systematic variability between optical properties at each station, as well as site back trajectories, suggest differences in aerosol processes, sources and transport. The development of consistent climatologies and additional analyses like the ones presented here can help provide a better understanding of trans-Arctic aerosol variability, which can be an asset for improving aerosol models in this unique and remote region.
Continuous Arctic Ocean Water Vapor Isotope Ratio (δ18O and δ2H) Measurements During a Summer Icebreaker Expedition
Warming in the Arctic is reducing sea ice, which may result in changes to the water cycle through increased atmospheric humidity. Here we present the first continuous record of water vapor isotope ratio (δ18O, δ2H, d-excess) measurements from the sub-Arctic and Arctic Ocean during ship transit through both open water and sea ice. As water vapor isotopes were collected across a spectrum of sea ice conditions, the influence of sea ice and availability of open water moisture sources on Arctic Ocean water vapor isotope values (particularly d-excess) is examined. Isotope values reveal characteristics about water availability at vapor sources, as influenced by presence of sea ice (e.g., ice covered arid or open water humid sources), and air parcel trajectory. Higher d-excess values were generally associated with more northern Arctic, ice covered, and arid vapor sources. Conversely, lower d-excess values were related to more southern, open water, and humid vapor sources. Additionally, water vapor isotopes while sea ice was present were generally characterized by more depleted δ18O and δ2H and higher d-excess values, relative to open water values. These water vapor isotope values also present information about potential shifts in moisture sources in an increasingly ice free Arctic Ocean. Understanding these shifts is important to learning about both modern and past patterns of Arctic atmospheric water movement and distribution.
Key Findings of the AMAP 2015 Assessment on Black Carbon and Tropospheric Ozone as Arctic Climate Forcers
The Arctic Monitoring and Assessment Programme (AMAP) established an Expert Group on Short-Lived Climate Forcers (SLCFs) in 2009 with the goal of reviewing the state of science surrounding SLCFs in the Arctic and recommending science tasks to improve the state of knowledge and its application to policy-making. In 2011, the result of the Expert Group’s work was published in a technical report entitled The Impact of Black Carbon on Arctic Climate (AMAP, 2011). That report focused entirely on black carbon (BC) and co-emitted organic carbon (OC). The SLCFs Expert Group then expanded its scope to include all species co-emitted with BC as well as tropospheric ozone. An assessment report, entitled Black Carbon and Tropospheric Ozone as Arctic Climate Forcers, will be published in 2015. The assessment includes summaries of measurement methods and emissions inventories of SLCFs, atmospheric transport of SLCFs to and within the Arctic, modeling methods for estimating the impact of SLCFs on Arctic climate, model-measurement inter-comparisons, trends in concentrations of SLCFs in the Arctic, and a literature review of Arctic radiative forcing and climate response. In addition, three Chemistry Climate Models and five Chemistry Transport Models were used to calculate Arctic burdens of SLCFs and precursors species, radiative forcing, and Arctic temperature response to the forcing. Radiative forcing was calculated for the direct atmospheric effect of BC, BC-snow/ice effect, and cloud indirect effects. Forcing and temperature response associated with different source sectors (Domestic, Energy+Industry+Waste, Transport, Agricultural waste burning, Forest fires, and Flaring) and source regions (United States, Canada, Russia, Nordic Countries, Rest of Europe, East and South Asia, Arctic, mid-latitudes, tropics, southern hemisphere) were calculated. To enable an evaluation of the cost-effectiveness of regional emission mitigation options, the normalized impacts (i.e., impacts per unit emission from each sector and region) were also calculated. Key findings from the 2015 assessment will be presented.
Monitoring the changing hydrology of the Arctic with isotopic tracers
Profound changes in the Arctic environment are associated with regime-changing perturbation of the Arctic hydrological cycle. Water transport from lower latitudes by storms is changing in intensity and magnitude as atmospheric circulation and humidity adjusts to climate forcing. Dramatic decline of sea ice has changed the evaporative source of water over the Arctic Ocean which has integrated impacts on the polar heat balance via coupling with clouds and the radiative budget. Rapid warming of the Artic terrestrial systems has dramatically influenced the seasonal snow pack, permafrost and runoff regimes. Consequently Arctic vegetation and root-zone ecosystems has undergone a shift, giving a response to water availability response coupled to the Arctic carbon budget. Projected to increase in magnitude of the change and impact over forthcoming decades, bringing to critical the need to evaluate the integrated and connectivity of the Arctic hydrology. Existing observational capacities are capable of identifying several of these changes, yet broad details on the path ways taken by water within the Artic remain poorly resolved. The stable isotopic chemistry of water has a demonstrated utility in providing observable measures of the transport of water from one system of the Arctic environment to another. We present results from recent measurements made on the Arctic isotope ratios in precipitation combined with a state-of-the-art climate model to which water “tagging” and isotope tracers have been fitted. We show over the duration of the past century systematic changes in Arctic hydrology are linked to the proportion of water advected from low latitude vs evaporated from the Arctic Ocean and transported by terrestrial systems. The terrestrial component in turn associated with increased productivity in Arctic ecosystems. The analysis shows the need for an observing system to properly capture the interplay between the several critical components: land, ocean and sea ice, and atmospheric transport.
Archaeological Sites as Nodes in True Long-term Arctic/Subarctic Ecological Observing Networks
Arctic and subarctic regions contain numerous archaeological sites where organic preservation is spectacular due to the cold climate. In addition to artifacts left by past humans, these sites contain ‘archives’ of plants and animals often in deep chronological sequences and spanning millennia. In this paper, we explore the value of these archaeological archives as “distributed observation networks of the past” and consider case examples from Iceland, Eastern and Northern Canada, Alaska and the Russian Far East. Well-dated archaeological faunal samples subject to morphological, isotopic, and genetic methods shed light on long-term ecosystem evolution in the context of climate changes more extreme than any recorded in the instrumental and historical records of recent centuries. New techniques make it possible to examine changes in productivity, food web dynamics, stock structure, population bottlenecks, extinctions, and population range shifts that can be compared to other records of climate and environmental change. Increasingly these records are being compared systematically across regions in ways that make it possible to explore coupled climate-ocean-ecosystem dynamics over large spatial scales and through century and millennial time scales. The cases presented have been brought into comparison thanks to collaborative work by the Paleoecology of Subarctic Seas (PESAS), North Atlantic Biocultural Organization (NABO), the Integrated History and Future of People on Earth (IHOPE), and the Global Human Ecodynamics Aliance (GHEA).
CHAOZ in a nutshell: Five years of work in twelve minutes
The BOEM-funded Chukchi Sea Acoustics, Oceanography, and Zooplankton (CHAOZ) study ran from September 2009 through August 2015, with field seasons in 2010-2012. The main objective of this study was to document the distribution and relative abundance of marine mammals (including bowhead, gray, beluga, killer, minke, humpback, right, and sperm whales, bearded and ribbon seals, and walrus) in areas of potential seismic surveying and oil and gas production and to relate variability in animal occurrence to oceanographic, atmospheric, and sea ice conditions, indices of prey density, and anthropogenic activities. Two years of long-term biophysical measurements (temperature, salinity, currents, ice keel depth, pressure, chlorophyll fluorescence, nitrate, oxygen, turbidity, and zooplankton volume backscatter) and passive acoustic recordings were collected at three mooring sites 40, 70, and 120 nm off Icy Cape, AK. In all three field seasons, sampling stations (CTD and Tucker sled tows) were run along lines off Icy Cape, Point Hope, Cape Lisburne, Point Lay, Wainwright, and Barrow Canyon. Continuous passive acoustic monitoring (via sonobuoys) was conducted 24/7 along the cruise track, and visual surveys were conducted during daylight hours using a three-person rotating team on big-eyes (25x) binoculars. These during-cruise measurements and observations served to ground truth/calibrate the long-term data records and provide finer scale sampling between the mooring sites. Simulations with the NCAR climate model were executed and analyzed, and a noise model was initiated. A near real-time passive acoustic auto-detection buoy was also deployed and successfully transmitted biological signals and noise level metrics. The results of this study are available as a final report to BOEM; this talk condenses the 600 page report into about a dozen key findings. A brief summary of each of these findings will be presented along with contact information and any associated publications.
Environmental drivers of benthic fish distribution in and around Barrow canyon: Connections between the northeastern Chukchi Sea and western Beaufort Sea
Barrow Canyon is a dominant feature of the northeastern Chukchi Sea shelf. It is oriented parallel to the shore and drops to depths around 150 m, around 20-40 km from shore. Oceanographic processes in Barrow canyon are expected to influence the ecology of organisms in the area. Furthermore, flow through Barrow canyon and around Point Barrow is expected to influence the western Beaufort Sea. To examine these expectations, the benthic fish community in and around Barrow Canyon in the northeastern Chukchi and western Beaufort Seas was surveyed with an 83-112 eastern otter trawl. Oceanographic data were collected at all trawl stations. Maps of the distribution of benthic fish indicate that Barrow Canyon influenced fish distribution, size and age. In particular, Arctic cod (Boreogadus saida) were more abundant, and were older and larger in the deep, cold, high salinity waters within and downstream of Barrow Canyon. Ten variables were selected for statistical analysis of the relationships between fish density and the environment . GAM and linear models confirmed that bottom depth, temperature and salinity were signficant factors affecting Arctic cod density. The water mass characteristics were consistent with winter water formed on the Chukchi Shelf. In addition, carbon, nutrients and zooplankton may have been advected from the south into the canyon and around Pt. Barrow into the Beaufort Sea. We hypothesize that Arctic cod occupied Barrow Canyon and waters downstream along the slope in the Beaufort Sea to take advantage of abundant, energy-rich prey, resulting in improved condition and survival. Climate-driven changes in sea ice dynamics, atmospheric forcing and current flow from the Bering Sea through Barrow Canyon and into the Beaufort Sea could have a downstream impact on ocean productivity and on organisms such as Arctic cod that appear to use Barrow Canyon and downstream for feeding and growth.
Finding the calls in the CHAOZ: marine mammals and oceanographic conditions off Alaska’s northern slope
The Chukchi Acoustics, Oceanography, and Zooplankton (CHAOZ) study was a five-year BOEM-funded, multi-disciplinary study (2010-2015). Its primary objective was to document the distribution of large whales in areas of potential seismic activity, and to relate these changes to oceanographic conditions, indices of potential prey density, and anthropogenic activities. Results presented here focus on the relationship between marine mammal distributions and oceanographic conditions. Three clusters of passive acoustic and biophysical moorings were deployed at 40nm, 70nm, and 110nm off Icy Cape, AK, and collected year-round passive acoustic data (16 kHz sampling rate, ~30% duty cycle) along with twelve different oceanographic measurements from two consecutive deployments (2010-2012). All acoustic recordings (100%) were analyzed using an in-house Matlab-based manual analysis program for twelve different Arctic and sub-Arctic cetacean and pinniped species, as well as for vessel, airgun, and ice noise. Generalized Additive Models (GAMs) were used to assess the effect of oceanographic conditions on marine mammal distribution, and marine mammal calling activity was plotted against eight oceanographic variables to determine if any positive/negative correlations existed on a temporal scale. Bowhead and beluga distributions showed similar patterns, with bimodal temporal distributions representing the fall and spring migrations. Ice concentration and month had the greatest effect on both bowhead and beluga presence, although bowheads were also strongly correlated with ice thickness and strong SSW winds. Gray whale detections (isolated on the inshore recorder) were too infrequent for conclusive results. Walrus and bearded seal calls were detected almost year-round; both species were correlated with ice concentration and variables that serve as proxies for prey availability. Detections of sub-Arctic species (e.g., humpback, fin, and killer whales) were rare. This study illustrates the importance of collecting concurrent passive acoustic and oceanographic data in a rapidly changing environment.
Inter-annual and Shorter-Term Variability in Physical and Biological Characteristics Across Barrow Canyon in August-September 2005-2015
Late summer physical and biological conditions along a 37-km transect crossing Barrow Canyon have been described for the past eleven years as part of an ongoing program, supported by multiple funding sources including the NSF AON, focusing on inter-annual variability and the formation of a bowhead whale feeding hotspot near Barrow. These repeated transects (at least two per year, separated in time by days-weeks) provide an opportunity to assess the inter-annual and shorter term (days-weeks) changes in hydrographic structure, ocean temperature and salinity, current velocity and transport, chlorophyll fluorescence, nutrients, and micro- and mesozooplankton community composition and abundance. Inter-annual variability in all properties was high and was associated with larger scale, meteorological forcing. Shorter-term variability could also be high but was strongly influenced by changes in local wind forcing. The sustained sampling at this location provides critical measures of inter-annual variability that should permit detection of longer-term trends that are associated with ongoing climate change.
Large whales at Arctic gateways: what AON data can tell us about the "new normal" Arctic
Changes in sea ice phenology have been profound in regions north of arctic gateways, where the seasonal open-water period has increased by 1.5-3 months over the past 30 years. This has resulted in changes to the Arctic ecosystem, including increased primary productivity, changing food web structure, and opening of new habitat. In the “new normal” Arctic, ice obligate species such as ice seals and polar bears may fare poorly under reduced sea ice while sub-arctic “summer” whales (fin and humpback) are poised to inhabit new seasonal ice-free habitats in the Arctic. Since 2006 and 2009, respectively, passive acoustic recorders have been included in Arctic oceanographic moorings in Davis and Bering Straits (supported by NSF-AON since 2011). These data were used to examine the spatial and seasonal occurrence of "summer" (fin and humpback) and “winter” (bowhead) whales from September through December. Acoustic occurrence of the three species concomitant with decadal-scale changes in seasonal sea ice was compared. In both Straits, fin and humpback whale acoustic detections extended from summer to late autumn. Bowhead whale detections generally began after the departure of the summer whales and continued through the winter. In every year, summer whales occurred in seasons and regions that used to be ice-covered.. This is likely due to both increased available habitat from sea ice reductions and post-whaling population recoveries. At present, in both Pacific and Atlantic gateways, there is spatial, but not temporal, overlap between summer and winter whales. In a future with further seasonal sea ice reductions, however, increased competition for resources between sub-Arctic and Arctic species may arise to the detriment of winter whales.
Measurements of solar radiation, temperature, and phytoplankton biomass in upper Arctic Ocean waters via autonomous buoys
As part of the Arctic Observing Network, a new ice-tethered buoy (Warming And irRadiance Measurements; “WARM”) has been developed for monitoring the role of sunlight in regulating ocean temperature, phytoplankton growth, and carbon cycling. A 20 or 50 m string supports sensors both within and below the ice for the hourly measurement of downwelling spectral and PAR irradiance, temperature, Chlorophyll a, light backscattering, and dissolved organic material (DOM). Two buoys were deployed in the Arctic Ocean in March 2014 and two in March 2015. Because the buoys are engineered to survive melt-out of first- year ice, they have successfully provided complete seasonal records of water column warming, phytoplankton abundance, and photo-oxidation patterns in the Pacific Arctic Region. The data collected are being used to help determine the role of reduced ice extent and thickness in the promotion of under ice warming, enhanced bottom ice ablation, increasing available photosynthetic radiation, under-ice blooms, and photo-oxidation of the DOM pool.
Observations so far have revealed under-ice daily warming driven by local solar radiation, as well warming pulses indicative of advection. High phytoplankton abundance was observed under the ice in June and July over the Chukchi shelf. Irradiance measurements show that this biomass could not have been grown in place and was likely advected, however, once there, phytoplankton were able to sustain low growth rates leading to nutrient limitation before open water status was reached. In open-water, chlorophyll concentrations were low, with the exception of a surface bloom in late fall. Importantly for the monitoring of Arctic ecosystems, most of the growth season in the Chukchi Sea was inaccessible to satellite remote sensing due to ice or cloud cover or low solar angle, making autonomous measurements critical for quantifying the effects of climate change on biological processes.
The Distributed Biological Observatory: Progress in Developing Data Sharing Mechanisms
The Distributed Biological Observatory (DBO; http://www.arctic.noaa.gov/dbo/) is a change detection array measuring biological responses to physical variability along a latitudinal gradient extending from the Northern Bering Sea to the Beaufort Sea in the Pacific Arctic. The DBO is transitioning into a decadal implementation phase with participation by international partners coordinated through the Pacific Arctic Group (PAG; http://pag.arcticportal.org/). The PAG is comprised of scientists and agency representatives from China, Japan, Korea, the US, Canada and Russia, with a supporting secretariat. Within the US, sampling is directly supported by the National Science Foundation, and the approach has also been included within the National Oceanographic and Atmospheric Administration Arctic Strategic Plan, the US Geological Survey ‘Science Needs’ Report, the Bureau of Ocean Energy Management Alaska Region Research Plan, the Interagency Arctic Research Planning Committee’s 5-Year Research Plan, the US National Ocean Policy Strategic Plan, and the National Strategy for the Arctic Region.
As the DBO is implemented, challenges remain including improving data sharing and exchange. An annual data meeting, in 2015 to be held in Incheon, Korea, and again in 2016 in Seattle, is a forum to increase data sharing from individual cruises so that the DBO can become operational as an arctic observational system. A data sharing policy and guidelines, in support of a metadata portal and data archive (dbo.eol.ucar.edu), have been agreed to (http://dbo.eol.ucar.edu/data_policy-dbo.html), and are essential for the long-term success of the DBO. The archive is complemented by a workspace supported by the Alaska Ocean Observing System (https://workspace.aoos.org/group/23134/projects). Progress is being made in making available observational data. For example data sets assembled during the Pacific Arctic Marine Arctic Regional Synthesis (North Pacific Research Board directed) are now publicly available; DBO-relevant examples include more than a decade of annual water column and sediment data from CCGS Sir Wilfrid Laurier cruises (pacmars.eol.ucar.edu).
The effects of loss of summer sea ice on a sea-ice obligate seabird
While the timing and nature of the loss of summer sea ice in the last four decades has been well documented, there are few long-term data sets on the biota associated with sea ice that allow examination of ecosystem response to the major oceanographic changes associated with loss of sea ice. To determine how decreases in sea ice have affected ice-associated marine predators, we examined historical (1975–1984) and recent (2003–2012) measures of nestling diet, breeding quality and success of a pack ice obligate marine bird, the black guillemot (Cepphus grylle mandtii), nesting on Cooper Island in the western Beaufort Sea. We examined decadal variation in late summer oceanographic conditions, nestling diet and success, and overwinter adult survival, comparing a historical period (1975–1984) with a recent (2003–2012) one. In the historical period sea ice retreated an average of 1.8 km per day from 15 July to 1 September to an average distance of 95.8 km from the colony, while in the recent period ice retreat averaged 9.8 km per day to an average distance of 506.9 km for the same time period. SST adjacent to the island increased an average of 2.9°C between the two periods. While Arctic cod comprised over 95% of the prey provided to nestlings in the historical period, in the recent period 80% of the years had seasonal decreases, with Arctic cod decreasing to <5% of the nestling diet, and sculpin (Cottidae), comprising the majority of the diet. A ﬁve-fold increase in the rate of nestling starvation and reductions in nestling growth and ﬂedging mass were associated with the shift from Arctic cod. The size of the Cooper Island guillemot colony has decreased by 50% since 1990, apparently in response to decreasing carrying capacity for an ice obligate in the Western Arctic.
The Fate of Sea Ice
Assessment of sea ice drift forecasts
Sea ice drift forecasts for the Arctic for the summer of 2014 are investigated. Sea ice forecasts are generated for 6 hours to 9 days using the Marginal Ice Zone Modeling and Assimilation System (MIZMAS) and 6 hourly forecasts of atmospheric forcing variables from the NOAA Climate Forecast System (CFSv2). Forecast sea ice drift speed is compared to observations from drifting buoys and other observation platforms. Forecast buoy positions are compared with observed positions at 24 hours to 9 days from the initial forecast. Forecast skill is assessed relative to forecasts made using an ice velocity climatology generated from multi-year integrations of the same model. RMS errors for ice speed are found in the order of 5 km/day for 24 h to 48 h using the sea ice model vs. 12 km/day using climatology. Following adjustments in the sea ice model to remove systematic biases in direction and speed, predicted buoy position RMS errors are improved from 8 km 6.5 km for 24 hour forecasts and 15 km after 72 hours. Using the forecast model increases the probability of tracking a target drifting in sea ice with a 10x10 km sized image to 95% vs. 50% using climatology. The results are generated in the context of planning and scheduling the acquisition of high resolution images which need to follow buoys or research platforms for scientific research but additional applications such as navigation in the Arctic waters may benefit from this accuracy assessment.
Autonomous Observations of the Heat and Mass Balance of Arctic Sea Ice
For the past decade the Arctic Observing Network included autonomous measurements of the mass balance of Arctic sea ice. A system of Ice Mass Balance (IMB) buoys measured time series of snow accumulation and ablation, ice growth, surface and bottom melt, and vertical profiles of air, snow, ice, and ocean temperature. The IMBs were collocated with other sensor systems providing an integrated dataset of atmosphere-ice-ocean conditions. The mass balance is the great integrator of heat and can be used to derive estimates of both the surface heat budget and ocean heat flux. Large spatial and interannual variations in surface and bottom melting are evident in the data record. For example, over the western Arctic the observed total summer surface melting ranges from as little as 0.05 m to over 0.75 m. Bottom melting exhibits an even more extreme range varying from 0.1 to 2.2 m. There are large regional and temporal variations in both surface and bottom melting. On average, surface melting decreases moving northward from the Beaufort Sea toward the North Pole, however interannual differences in atmospheric forcing can overwhelm the influence of latitude. Substantial increases in bottom melting are a major contributor to ice losses in the Beaufort Sea, due to decreases in ice concentration. In the central Arctic, surface and bottom melting demonstrate interannual variability, but show no strong temporal trends from 2000 to 2014. This suggests that under current conditions summer melting in the Central Arctic is not large enough to completely remove the sea ice cover.
Characterizing Arctic sea ice topography using high-resolution IceBridge data
Here we present a detailed analysis of Arctic sea ice topography using high resolution, three-dimensional, surface elevation data from the NASA Operation IceBridge Airborne Topographic Mapper (ATM).
Surface features in the sea ice cover (from ice deformation and snow redistribution) are detected using a novel feature-picking algorithm. We derive information regarding the height, orientation and spacing of `unique’ surface features from 2009-2014 across first-year and multiyear ice regimes within the Beaufort/Chukchi and Central Arctic regions.
The sea ice topography exhibits strong spatial variability, including increased surface feature height and volume within the multi-year ice regimes. The ice topography also shows a strong coastal dependency, with the feature height increasing as a function of proximity to the nearest coastline, especially north of Greenland and the Canadian Archipelago. The interannual variability in feature height and volume, especially north of Greenland, alludes to the importance of ice deformation variability in the sea ice mass balance.
A strong correlation between surface feature height and sea ice thickness (from the IceBridge sea ice product) demonstrates the potential for skillful (and quick) estimates of ice thickness based on surface measurements alone.
Identifying Dynamical Forcing and Cloud-Radiative Feedbacks Critical to the Formation of Extreme Arctic Sea-Ice Extent in the Summers of 2007 and 1996
Along with significant changes in Arctic climate system, the largest year-to-year variation in sea-ice extent has occurred in the Laptev, East Siberian, and Chukchi seas (define it here as the Area Of Focus, AOF), where two extremes of opposite signs were observed in the summers of 2007 and 1996. To untangle underlying forcing and feedbacks critical to the formation of the minimum (maximum) Arctic sea-ice extent of 2007 (1996), we examined in details the corresponding 2007 and 1996 anomalies of the large-scale atmospheric circulation and atmospheric physical parameters relevant to sea-ice variation utilizing satellite-derived sea-ice products and the NASA MERRA reanalysis. Our results indicate that, in addition to a triggering role of spring large-scale atmospheric circulation anomaly, a positive cloud-radiation-precipitable water vapor (PWV) feedback played the most important role in driving the sea-ice extent to a record low in the summer of 2007. Specially, atmospheric circulation change in spring induced anomalous southerly winds from the North Pacific not only advected more warm air, but also brought more water vapor to the AOF and formed more clouds. When cloud fraction (CF) was high and Arctic surfaces were covered by snow and ice, particularly during the onset of sea-ice melting (May-June), the cloud-greenhouse (LW) effect overwhelmed the cloud-albedo (SW) effect, producing a positive cloud radiative effect on surface radiation budget. Rising surface temperature subsequently enhanced evaporation and elevated atmospheric PWV, which drastically increased downwelling LW flux activating another positive feedback to the surface temperature. As sea-ice melting continued, additional SW (and LW) radiation was absorbed by open seas to increase surface temperature, and more water vapor evaporated to form more clouds, further accelerating sea-ice retreat through the positive cloud-radiation-PWV feedback. By contrast, when sea-ice reached an anomalously high extent in the summer of 1996, anomalous northerly winds and negative anomalies of surface temperature, CF, PWV, surface LW and total energy fluxes were reached. The findings reported here have major implications for improving the simulation of Arctic sea-ice variability and the related extremes of sea-ice extent in a climate model.
Interdisciplinary Observations of Air-Ocean Energy Fluxes During Arctic Freeze-Up
This presentation will use atmospheric and ocean mixed-layer observations from three cruises during the past two years to illustrate how air-ice-ocean observations can be combined to better understand the magnitude and variability of the air-ocean energy fluxes, the sources of the variability, the flux impact on ocean mixed-layer thermal structure, and how these surface energy fluxes impact initial ice formation. The measurements were made during cruises of the R/V Oden in July-Sep 2014 (ACSE/SWERUS), the R/V Mirai in Sep 2014, and R/V Sikuliaq in Oct 2015 (Sea State). The first two cruises obtained measurements near the ice edge in the Laptev and Chukchi Seas and include the onset of continuous ocean heat loss and the initial episodic ice formation. Observations from the Sikuliaq near the advancing ice edge in the Beaufort/Chukchi Sea will be very preliminary but should include the core period for southward advance of the ice. Frequent atmospheric soundings and continuous remote-sensor measurements provide the vertical kinematic and thermodynamic structure in the lower troposphere. Broadband radiometers, turbulent flux sensors, surface temperature sensors, surface characterization instruments, and basic meteorological instrumentation provide continuous measurements of all surface energy flux terms (shortwave/longwave radiation, sensible/latent turbulent heat fluxes), allowing the quantification of the total energy exchange between the ocean and the atmosphere. Furthermore, each cruise provided continuous measurements of the upper-ocean temperature and salinity and frequent CTD measurements of the ocean temperature and salinity profiles, providing estimates of upper-ocean energy evolution. Various methods for characterizing the ocean surface (open ocean, ice cover, ice thickness, wave state, etc.) allow linking energy changes with changes in ocean surface conditions. The presentation will highlight combining these interdisciplinary observations for improved process understanding.
Loitering of the retreating sea ice edge in the Arctic Seas
Each year, the arctic sea ice edge retreats from its winter maximum extent through the Seasonal Ice Zone (SIZ) to its summer minimum extent. On some days, this retreat happens at a rapid pace, while on other days, parts of the pan-arctic ice edge hardly move for periods of days up to 1.5 weeks. We term this stationary behavior “ice edge loitering,” and identify areas that are more prone to loitering than others. Generally, about 20-25% of the SIZ area experiences loitering, most often only one time at any one location during the retreat season, but sometimes two or more times. The main mechanism controlling loitering is an interaction between surface winds and warm sea surface temperatures in areas from which the ice has already retreated. When retreat happens early enough to allow atmospheric warming of this open water, winds that force ice floes into this water cause melting. Thus while individual ice floes are moving, the ice edge as a whole appears to loiter. The time scale of loitering is then naturally tied to the synoptic time scale of wind forcing. Perhaps surprisingly, the area of loitering in the arctic seas has not changed over the past 25 years, even as the SIZ area has grown. This is because rapid ice retreat happens most commonly late in the summer, when atmospheric warming of open water is weak. We speculate that loitering may have profound effects on both physical and biological conditions at the ice edge during the retreat season.
NASA IceBridge: Scientific insights from airborne surveys of the polar sea ice covers
The NASA Operation IceBridge (OIB) airborne sea ice surveys are designed to continue a valuable series of sea ice thickness measurements by bridging the gap between NASA’s Ice, Cloud and Land Elevation Satellite (ICESat), which operated from 2003 to 2009, and ICESat-2, which is scheduled for launch in 2017. Initiated in 2009, OIB has conducted campaigns over the western Arctic Ocean (March/April) and Southern Oceans (October/November) on an annual basis when the thickness of sea ice cover is nearing its maximum. Data from the campaigns are available to the research community at: http://nsidc.org/data/icebridge/.
This presentation will summarize the spatial and temporal extent of the OIB campaigns and their complementary role in linking in situ and satellite measurements. We will demonstrate the utility of the multi-instrumented OIB data set in advancing observations of sea ice processes across all length scales. Key scientific insights gained on the state of the sea ice cover will be highlighted, including snow depth, ice thickness, surface roughness and morphology, and melt pond evolution.
The Ice, Cloud, and Land Elevation Satellite (ICESat-2) Mission
NASA’s second-generation Ice, Cloud, and Land Elevation Satellite (ICESat-2), currently planned for launch in late 2017, will provide observations to quantify the changes in ice sheets and sea ice, and key insights into their behavior. To achieve this, precise laser measurements of surface elevation, building on the capabilities of its predecessor (ICESat-1), will be acquired to assess ice sheet mass balance and processes, as well as the time-varying thickness and volume of sea ice in the Arctic and Southern Oceans. ICESat-2 will also measure sea surface height in the ice free sub-Arctic seas and provide large-scale vegetation biomass estimates through the measurement of vegetation canopy height. Combining data from the ICESat-2 mission with existing and forthcoming altimetry datasets will yield a 15+ year record of elevation change. We briefly describe the unique instrument and the expected data quality to address the science objectives.
Tracking a newly predominant ice type: SIZONet observations of first-year ice thickness north of Alaska
Seasonally-grown, first-year (FY) sea ice is rapidly becoming the dominant ice type in the Arctic Ocean. Since early 2000, the UAF sea ice mass balance station (MBS) has recorded changes in the growth and melt of landfast FY ice near Barrow, Alaska, during this critical transition phase. Despite considerable interannual variability, these data suggest FY ice thickness near Barrow is decreasing. While the trend is not significant, the mean annual maximum ice thickness of 1.5 m from 2000-2015 is significantly thinner than the thicknesses of around 1.8 m commonly reported during the 1970s. Key drivers of thickness variations are changes in the onset of ice formation in the fall and snow depth.
Since 2007, the Seasonal Ice Zone Observing Network (SIZONet) has conducted airborne electromagnetic (AEM) ice thickness surveys in the Chukchi and Beaufort Seas near Barrow around the time of maximum thickness. Modal thicknesses, taken to represent level FY ice, exhibit interannual variability similar to that observed in the landfast ice, demonstrating that the MBS data are representative of the regional thermodynamic regime and underscoring the value of long term monitoring at Barrow.
Despite targeting multiyear (MY) ice wherever possible, in all but the first two surveys the presence of MY ice was insufficient for determining regional thicknesses from PDFs of the AEM data. However, in conjunction with in-situ observations, changes and variability in the thickness of MY ice exiting the Beaufort Sea can be tracked. Major reductions in level MY ice thickness are the result of enhanced bottom and surface melt. The AEM surveys also identified areas of recurring grounded ice, such as Hanna Shoal, where ridges in excess of 30 m thick are found. In a seasonally-dominated ice pack, such locations may become increasingly important as refugia for marine mammals and sources of hazardous ice for maritime activities.
Ocean Circulation and Mixing
25 years (1990-2015) of year-round measurements in the Bering Strait - what do we know, and what do we still not know?
The ~85km wide, ~50m deep Bering Strait is the only oceanic conduit between the Arctic and the Pacific Oceans. Waters flowing through this strait trigger the seasonal melt-back of sea-ice, provide ~1/3rd of the Arctic’s freshwater input, and are an important nutrient source for Chukchi and Arctic ecosystems.
Since 1990 (with only a 1-year break), year-round moorings have measured the physical properties of the flow through the strait. Serviced annually, the moorings have allowed us to quantify the strong seasonal cycle and (since 1998) assess the significant interannual changes in water properties and volume, heat and freshwater fluxes.
The most recent data (recovered this summer) show continuation of the flow increase that started in 2001, with 2014 yielding record-maximum transports both in volume flux (~1.2Sv), and freshwater transport (~3700km3/yr, relative to 34.8psu). These increases likely halve the residence time of waters on the Chukchi Shelf (compared to 2001); alter the arrival time and depth of the waters carrying heat and nutrients into the Arctic; and influence Arctic stratification. Indeed, data suggest the Bering Strait freshwater flux has larger inter-annual variability than the other major external sources of Arctic freshwater (rivers and net precipitation). We discuss causes of these increases, including a long-term freshening trend in the strait and the influence of local wind.
We also present the first interannual assessment of sea-ice flux through the strait, with data (2007 onwards) yielding annual mean sea-ice thicknesses ranging from <1m to >2m, and annual mean sea-ice fluxes varying even in direction.
Time allowing, we also consider important, but less well-understood features of the strait – the role of the Alaskan Coastal Current “spilling” warm fresh waters into the central Chukchi, influencing stratification and mixing; and the mixing and biological significance of semi-trapped eddies behind the Diomede Islands in the center of the strait.
AON observations in the eastern Arctic help understand current state of the climate system
During the two most recent years of 2014 and 2015, sea-ice decline in the eastern Eurasian Basin (EB) was massive, and at least comparable to or even exceeding that of the western Arctic. How much of the recent dramatic reduction in sea ice in the eastern EB is due to oceanic heat carried within the ocean interior by a system of pan-Arctic boundary currents? What are the processes, and their magnitudes, controlling these along-slope heat, salt, and water transports? NABOS (= Nansen and Amundsen Basins Observational System) program, as a part of the Arctic Observing Network (AON), is designed to compile a cohesive picture of the climatic changes in the Eurasian and Makarov basins (EMB) of the Arctic Ocean, with particular focus on understanding three major observational targets:
(1) Along-slope AW transport by the boundary currents
(2) Interaction of AW branches with shelf waters, deep basin interior and upper ocean
(3) EMB indications of changes in the upper ocean circulation.
Two cruises conducted in the high Arctic in 2013 and 2015 provided a wealth of data which have suggested that continental margins play a critical role in the transportation of heat and salt from subpolar basins into the Arctic Ocean interior, as well as the regulation of shelf-deep basin exchanges. We report recent (September 2015) observations from the East Siberian Sea that indicate potential upwelling of warm, Atlantic waters onto the shelf/slope and mixing with oxygen-poor and nitrate-rich shelf bottom waters. This upward flux of Atlantic water heat could delay the onset of sea ice formation in this region.
Arctic Tides: Role in the coupled ocean/sea-ice system
Large tidal height ranges occur in the gateways to the North Atlantic (Barents Sea, Baffin Bay and Canadian Arctic Archipelago) and energetic tidal currents are present over the Eurasian continental shelves and Davis Strait. The strong currents generate energetic mixing in the bottom boundary layer, in the surface layer under sea ice where the concentration is high, and in the pycnocline through generation of baroclinic tides and higher-frequency internal waves. In models, these periodic processes are rectified into substantial changes in the Arctic Ocean hydrographic structure and circulation. The co-location of strongest tidal currents with the Atlantic Water circulation as a boundary current along the Eurasian Arctic continental slope and across the Barents Sea suggests that tides affect intermediate-layer water mass properties throughout the Arctic, even in regions where local tides are weak such as in the western Arctic.
In regions where tidal current amplitudes and phases change rapidly, the tides exert a periodic shear and strain on the sea ice, creating intermittent leads and increasing sea-ice roughness. As with mixing, these processes are rectified into large-scale consequences for the ice pack, and also for net ocean-atmosphere heat exchange. Models indicate that the consequences of tides on these exchanges is seasonally dependent, with complex feedbacks between tides, sea ice, and net surface radiation balance. These feedbacks will vary as the annual cycle of Arctic sea ice cover shifts relative to the annual cycle of atmospheric state including air temperature and downwelling radiation.
Circulation patterns and mean residence times of waters in the Arctic Ocean derived from 25 years of tracer observations
Between 1987 and 2012, we collected tracer data on numerous sections covering all major regions and basins of the Arctic Ocean. Here we present the main results obtained from our tracer data sets including (1) circulation patterns and spreading velocities in the upper water column, (2) renewal rates of the upper, deep, and bottom waters in the individual basins, and (3) freshwater, components, inventories and sources. The circulation patterns derived from tracer age gradients are compared with those obtained from hydrographic and current meter data and their variability over the past 25 years is discussed. The tracer gradients in the deep and bottom waters point towards well homogenized water reservoirs in the Canadian Basin with renewal times of roughly 400 years. The source waters of the deep basins are mainly of Atlantic origin as shown by the stable isotope ratios of water. Freshwater components are identified and quantified using a combination of stable isotopes, salinity, and nutrients and their variation along major sections are discussed in the context of the overall dynamics of the circulation in the Arctic Ocean. Finally, we discuss the frequency of repeat hydrography/tracer observations required to resolve variability observed in our data.
Dramatic Weakening of the Pacific Water Boundary Current in the Beaufort Sea during the first decade of the 2000s
Pacific-origin water has profound impacts on the physical state and ecosystem of the Western Arctic Ocean. The cold winter water ventilates the upper halocline and supplies nutrients that fuel primary productivity, while the warm summer waters melt sea ice and supply freshwater to the Beaufort Gyre. Here we use mooring data collected as part of the Arctic Observing Network (AON) to examine the interannual trends in the current over the period 2002-2011. Strikingly, the volume transport of the current has decreased by more than 80%, despite the fact that the flow through Bering Strait has increased over this time period. The largest changes have occurred in the summer months. Using atmospheric reanalysis fields and weather station data, we demonstrate that an increase in summer easterly winds is the primary cause for the reduction in transport, which is largely dictated by the behavior of the two atmospheric centers of action, the Beaufort High and Aleutian Low. Using additional mooring and shipboard data, together with satellite fields, we argue that a significant portion of the mass and heat passing through Bering Strait in recent years has been advected northwestward out of Barrow Canyon - rather than entering the boundary current in the Beaufort Sea - where it is responsible for a significant portion of the increased sea ice melt in the basin.
Five Years of Ecosystem Data from the Northeastern Chukchi Sea
As part of three BOEM projects (CHAOZ, ArcWEST and CHAOZ-Extension) ship-board observations were collected during late summer from 2010 – 2015. In addition, year-long biophysical moorings were deployed each year. Moorings measured temperature, salinity, oxygen, PAR, fluorescence, nitrate, ice thickness, currents, and plankton backscatter (ADCP). Alaska coastal, Bering Sea, Pacific winter, and Barrow Canyon waters were evident. Export of chlorophyll to the bottom occurred each year in June/July. Transport calculated from current measurements indicate that ~40% of the transport through Bering Strait passes the Icy Cape mooring line. Maximum monthly-mean transport (>0.8 Sv) is in July with low inter annual variability, while the lowest monthly transports are in December – April with high interannual variability. Currents are significantly correlated with alongshore winds. While flow along the Alaskan coast is typically northeastward toward Barrow Canyon, reversals do occur. During flow reversals, Atlantic Water (AW) has been observed to upwell from deeper than 200 m in the Arctic Basin onto the Chukchi Shelf via Barrow Canyon. Most observations of AW on the Chukchi shelf have been in or near Barrow Canyon; observations of AW farther onto the shelf are rare. Despite mooring location on the shelf ~225 km from the head of Barrow Canyon, three AW events have been observed during three winters of moored observations at mooring C1 (70.8°N, 163.2°W). The first AW event was observed near the ice edge during ice advance while the other two events were associated with polynyas, suggesting that both latent and sensible heat mechanisms may be important to the formation and maintenance of some Chukchi Sea polynyas.
NABOS observations evaluate shift to more dynamic state of the eastern Arctic Ocean
Most recent mooring observations conducted during NABOS-2015 (Nansen and Amundsen Observational System) cruise suggest that the Eurasian Basin (EB) as a part of the Arctic Ocean is in its extreme state. In this cruise eight moorings deployed in the EB with full two-year-long records of collected data were successfully recovered. Observations reveal exceptionally strong (>3ºC) summer 2014 warming of the upper ocean layer in the EB off Novosibirskiye Islands. We speculate that increased heat storage of this layer plays a role in unprecedented sea-ice decline evident in the eastern EB during the last two years. Accompanied velocity observations in this layer show significant seasonal amplification, caused by changes of ice conditions with more than ten-fold increase of current velocities in ice-free season.
Mooring array deployed across the continental slope of the Laptev Sea demonstrate strong seasonal signal - the most powerful mode of variability in the eastern EB. For instance, 2013-15 mooring series have revealed a strong (>2 ºC) seasonal signal in Atlantic Water (AW) temperatures, which is accompanied by >10 cm/s seasonal changes of along-slope current velocities over the sallow (< 1000 m ) part of the slope. The amplitudes of seasonal signals change drastically at deep-water (~3000 m) moorings, likely suggesting strong regional interplay between local and remote sources of seasonality there potentially enhanced by declined ice cover. Using this array we estimated 2013-15 eastward (AW) transport through the 125ºE sections as 4.6 Sv, which is comparable with estimates of AW transport in Fram Strait (~3-4 Sv).
Concluding, we note that collected observations provide crucial information to further our understanding of the Arctic as a whole system and to improve possibilities to predict the future state of the Arctic Ocean.
The Arctic Freshwater Balance - A Network Perspective
Arctic freshwater plays a fundamental role in the global hydrologic cycle, balancing poleward transport of water vapor within the atmosphere with accumulation and export of liquid freshwater and ice to lower latitudes. Within the Arctic, freshwater forms a shallow, buoyant boundary layer that acts as a barrier to vertical mixing, insulating sea ice from oceanic heat stored in water masses below. Freshwater, in the form of sea ice, reflects solar radiation and modulates the transfer of momentum from atmosphere to ocean. The fate of Arctic freshwater thus impacts Arctic circulation, sea ice evolution and global climate.
Recent analyses have exploited new observations of unprecedented temporal and spatial scope to build upon the seminal 1989 Arctic freshwater synthesis of Aagaard and Carmack. The network of measurements includes over a decade of simultaneous measurements at the major gateways (Bering Strait, Fram Strait, Davis Strait and the Barents Sea Opening), distributed in situ observations in the Arctic interior and satellite remote sensing, which have facilitated quantification and attribution of recent changes in the Arctic freshwater system. This presentation will review results from selected synthesis efforts accompanied by an overview of the observing system that supported them.
The North Pole Environmental Observatory: Fifteen years of Arctic observing and future directions
The North Pole Environmental Observatory was started in 2000 to track and understand newly observed and dramatic changes in the central Arctic Ocean and their connection with climate variability. Since its inception, this long-term program of the Arctic Observing Network has included buoy deployments, moorings, and repeat hydrographic surveys using aircraft. The hydrographic surveys have expanded to include multiple biogeochemical observations as well as the addition of internal wave and mixing observations. The in-situ observations of NPEO have increasingly been integrated with satellite altimetry and gravimetry observations to expand the spatial and temporal scope of the processes that can be addressed. The observatory has supplied collaborating science projects with operational and logistics support as well as a steady stream of data from a remote but important region that is sensitive to circulation change. In this presentation, we will give a brief summary of the project and outline future directions, including tracking changes in the Transpolar Drift to estimate fluxes of freshwater and its constituents and the relation of these with hemispheric indices and exports through Fram Strait.
Robust Autonomous Arctic Observations: Successes and Challenges
Arctic Watch: Acoustic in an Arctic Ocean Observing System.
Synoptic in-situ year-round observational technologies are needed to monitor and forecast changes in the Arctic atmosphere-ice-ocean system at daily, seasonal, annual and decadal scales. This paper addresses the use of regional to basin wide multipurpose acoustic networks in the Arctic and sub-Arctic. These networks provide communication, underwater and under-ice navigation, passive monitoring of ambient sound (ice, seismic, biologic, and anthropogenic), and acoustic remote sensing (tomography and thermometry) supporting and complementing data collection from platforms such as floats, moorings and vehicles. This paper supports the development and implementation of regional to basin-wide acoustic networks as an integral component of a multi-disciplinary in-situ Arctic Ocean observatory.
Many steps towards a pan-Arctic observing system have been taken. In 1994, a trans-Arctic acoustic propagation experiment provided the first evidence of basin-scale warming of the Atlantic Intermediate Water. In 1998–1999, a similar experiment documented continued basin-scale warming of the AIW. Ten years later, a prototype single-track ocean acoustic tomography system was deployed from 2008 to 2009 to measure the depth-averaged temperature in the eastern half of Fram Strait. Subsequently, three moored acoustic transceivers were deployed from 2010 to 2012 in a triangle with a moored receiver in the center. This experiment was the first implementation of a multipurpose acoustic network for tomography, passive acoustic monitoring, and navigation of gliders. In 2014, the acoustic monitoring of the Fram Strait was continued and extended by the deployment of five acoustic moorings. The acoustics system is augmented by oceanographic instrument, and will be recovered in 2016. In 2016, a tomographic experiment is planned in the Beaufort Sea.
Finally, we present the plan for implementation of an international Arctic Watch experiment with a source mooring at the North Pole and receiver moorings in the eastern (Nansen Basin) seas and western Beaufort/Chukchi Seas of the Arctic Ocean.
Autonomous Investigations of Marginal Ice Zone Processes- Changing Feedbacks and Observational Challenges
The observed reduction of Arctic summertime sea ice extent and expansion of the marginal ice zone (MIZ) have profound impacts on the balance of processes controlling sea ice evolution, including the introduction of several positive feedback mechanisms that may act to accelerate melting. Examples of such feedbacks include increased upper ocean warming though absorption of solar radiation, elevated internal wave energy and mixing that may entrain heat stored in subsurface watermasses (e.g. the relatively warm Pacific Summer (PSW) and Atlantic (AW) waters) and elevated surface wave energy that acts to deform and fracture sea ice, all of which grow in importance with increasing open water extent.
Investigations of MIZ dynamics must resolve the short spatial and temporal scales associated with the processes that govern the exchange of momentum, heat and freshwater near the atmosphere-ice-ocean interface while also achieving the spatial scope and temporal persistence required to characterize how the balance of processes shifts as a function of evolving open water fraction and open water fetch to the south. The recent Office of Naval Research (ONR) Marginal Ice Zone program employed an integrated system of autonomous platforms to provide high-resolution measurements that extend from open water, through the MIZ and deep into ice-covered regions while providing persistence to quantify evolution over an entire summertime melt season. This talk will provide an overview of the strategy developed by the ONR MIZ team and present early results from the 2014 field program.
Enhancing Observational Capabilities for Arctic Ocean Ecosystems: Innovations Using Ice-Tethered Profilers
Between 2011 and 2013 eight Ice-Tethered Profilers (ITPs) were outfitted with bio-optical/biogeochemical sensor suites and deployed in perennially ice-covered regions of the Arctic Ocean. These deployments represent an important new approach for obtaining biological and bio-physical observations of the changing Arctic in ocean ecosystems that are extremely difficult to sample over seasonal and annual scales. These ITPs were deployed in the central Arctic and Beaufort Gyre and carried sensors for chlorophyll fluorescence, optical scattering, CDOM fluorescence, and incident solar radiation (Fig. 1). They have generated unique, long-term and high-resolution time series of under-ice irradiance, algal biomass, particulate scattering, and organic matter concentrations in the top 800m of the Arctic Ocean, with profiles conducted daily or better. Two of these systems operated for twelve months or longer, capturing the entire annual trend in these bio-optical properties in the central Arctic Ocean and Beaufort Sea respectively. These observations were used to estimate the timing and duration of the under-ice algal growing season, the subsequent export of particulate organic matter later in the season, and the occurrence of intermittent physical perturbations that affect biological and bio-optical distributions. The ITP’s high-resolution profiling enables a more accurate temporal assessment of the timing and magnitude of intermittent events down to the time scale of less than a single day, in principle. These initial eight profilers provide some of the highest-resolution observations of the basic seasonality in fundamental biological and bio-physical dynamics in perennially ice-covered regions of the Arctic Ocean, and demonstrate the utility of autonomous long-term observing in the deep central Arctic, for upper-ocean ecosystems currently experiencing significant environmental change.
Integrated analysis of high-resolution autonomous observations in the Pacific Arctic Region
Many physical changes are currently underway in the Arctic Ocean related to reductions in sea ice extent and persistence, including increased irradiance, freshening, warming, and acidification. However, the small-scale variability and rapid changes typical of the ice edge environment represent clear technical challenges for ocean observations, especially using traditional observational methods. In the summer of 2015, we deployed multiple autonomous platforms to track circulation, flow, and biogeochemical variables through the Chukchi Sea just after sea-ice retreat. Two Liquid Robotics wave gliders ran repeat tracks across the Central Channel and Hanna Shoal to study the evolution of chemical parameters during the early ice melt season. To track surface flow impacted by ice melt, 12 drifters with 30 m drogues were released from multiple locations over the southern Chukchi Shelf. We also deployed a variety of novel sensors on new and existing moored systems near the C2 time series site. Together, these integrated data from moored and mobile autonomous systems successfully provided new insights into the physics and biogeochemistry of the ice-edge environment, with clear implications for carbon cycling.
Long-term observations of atmospheric CO2, O3 and BrO over the transitioning Arctic Ocean pack-ice: The O-Buoy Chemical Network
Autonomous, sea ice-tethered buoys (“O-Buoys”) are being deployed across the Arctic sea ice for long-term atmospheric measurements (2009-2016), as part of the US NSF-funded Arctic Observing Network (AON). These buoys provide in-situ concentrations of ozone, CO2 and BrO, as well as meteorological parameters and imagery, over the frozen ocean. The O-Buoy has bi-directional communication capabilities and transmits data hourly. O-Buoys were designed to transmit data over a period of 2 years while deployed in sea ice, as part of automated ice-drifting stations. Seasonal changes in Arctic atmospheric chemistry are influenced by changes in the characteristics and presence of the sea ice vs. open water as well as air mass trajectories, especially during the winter-spring and summer-fall transitions when sea ice is melting and freezing, respectively. The O-Buoy Chemical Network (http://www.o-buoy.org) provides the unique opportunity to observe these transition periods in real-time with high temporal resolution, and to compare them with those collected on land-based monitoring stations. Due to the logistical challenges of measurements over the Arctic Ocean region, most long term, in-situ observations of atmospheric chemistry have been made at coastal or island sites around the periphery of the Arctic Ocean, leaving large spatial and temporal gaps that O-Buoys overcome. Advances in floatation, communications, power management, and sensor hardware have been made to overcome the challenges of diminished Arctic sea ice which have resulted in our longest deployments so far. O-Buoy data provide insights into questions pertinent to seasonal, interannual, and spatial variability in atmospheric composition, changes in halogen and O3 chemistry as a function of spring-enhanced bromine chemistry , and enhancement of the atmospheric CO2 signal over the more variable and porous pack ice, among others. As part of AON, we openly provide data to the community via the data portal ACADIS (http://www.acadis.org).
Near-surface temperature gradients detected by microbuoys in the Arctic Ocean
With the increasingly long open water season in the Arctic Ocean comes significant solar heating. Microbuoys, deployed from UAS or other platforms, provide minimally-invasive sub-surface in situ measurements over a sub-seasonal period of time for little cost. Warmer temperatures and increasing freshwater input are changing the stratification in the upper Arctic Ocean. The 2013 MIZOPEX campaign used unmanned aircraft to deploy several microbouys into the Arctic Ocean near (20-40km) the coast of Alaska. Observations from these buoys indicate that there are, when there is little wind, significant temperature gradients in the top two meters of the ocean. Near ice floes in the MIZ, cold, fresh meltwater pools at the surface creating strongly negative temperature gradients of 2°/meter. Further south, where ice cover had been absent for 10-14 days, surface temperatures were significantly higher (2-6°C) and strongly positive temperature gradients caused by the absorption of solar radiation dominated. These temperature gradients have two major implications: influencing heat fluxes in the upper ocean, and skewing estimates of mixed layer temperature from SST. This presentation covers the two types of observed surface temperature gradients and their influence on heat fluxes and local ice melt, showing the utility of small sensors for measuring near-surface conditions.
Quantifying Soil Properties and Relationship to Vegetation Dynamics in Arctic Tundra using Aerial Platforms and Geophysical Monitoring
Although hydrological and biogeochemical processes in terrestrial ecosystems are influenced by interactions occurring within the shallow subsurface, the land surface, and the vegetation, coincident monitoring of above- and below-ground processes is challenging. In this study, we developed an above- and below-ground autonomous monitoring strategy and used it to investigate temporal and spatial linkages between soil and landscape property dynamics. We tested the new monitoring strategy in the permafrost-rich Arctic tundra ecosystem in Barrow, AK along transects that extend from 35m to 500m and that traverse a range of geomorphological conditions, including low- to high- centered polygons. Landscape characteristics were obtained through digital surface model reconstruction and multi-spectral imaging measurements using kite- and autonomous pole- based platforms. Soil properties were monitored using autonomous electrical resistivity tomography (ERT) and soil temperature/moisture sensors as well as through soil sample analysis.
The novel monitoring strategy enabled us to image and quantify key freeze-thaw process in permafrost soil, to identify spatiotemporal links between various soil and landscape properties (incl. vegetation, topography, thaw layer thickness, water content, temperature, electrical conductivity, and snow thickness), to evaluate various ground- and aerial-based approaches and proxies to monitor soil properties, and to constrain hydro-thermal-geophysical models. Among other results, a relatively strong relationship between changes in soil electrical conductivity, water content, thaw layer thickness and vegetation state was identified, highlighting the covariance and time lag between thaw, soil moisture and vegetation growth as a function of geomorphology. ERT was useful for spatiotemporal monitoring of soil water content, and when combined with low-altitude aerial imaging, for extending estimates of above- and below-ground behavior over larger spatial scales. The developed monitoring strategy marks an important advance in understanding how complex multi-compartment terrestrial ecosystems function and in providing estimates that can be used to initialize and parameterize models simulating ecosystem feedbacks to climate.
Status of the Beaufort Gyre Observing System (BGOS, 2003-2015)
The Beaufort Gyre system is a unique circulation component within the Arctic physical environmental system that reflects a set of specific atmospheric, sea-ice, and oceanic conditions having significant interrelationships with the Arctic-wide as well as global climate systems. Observations spanning 2003-2014 reveal that the Beaufort Gyre region accumulated more than 5000 km3 of liquid freshwater relative to the climatology of the 1970s. Recent results suggest that the Beaufort Gyre system may be entering a period of freshwater release which has the potential to cause another Great Salinity Anomaly in the subpolar North Atlantic. Since 2003, thirteen years of observations, supported by NSF, the Woods Hole Oceanographic Institution and the Department of Fisheries and Oceans, Canada, and different institutions of Japan have been conducted in the Beaufort Gyre region of the Arctic Ocean. To date, the Beaufort Gyre Observing System (BGOS) program has sequentially deployed and recovered 36 moorings at 3-4 fixed locations that measured water temperature and salinity (T&S), ocean currents, sea ice drafts, bottom pressure, and collected sediment samples; and amassed hydrographic data from more than 400 CTD (T&S, biogeochemistry) and more than 600 XCTD (T&S) casts along standard sections in fall during each year of the program. BGOS has had strong ties through logistics and data sharing with at least ten other AON projects (including ITP, IMB, AOFB, O-Buoy, UpTempO, IABP) and looser associations with many others. Over 100 peer-reviewed publications by authors from different countries and institutions have utilized BGOS data.
The U.S. Interagency Arctic Buoy Program (USIABP) and International Arctic Buoy Programme (IABP)
Our ability to predict weather and sea ice conditions requires in situ observations of surface meteorology and ice motion. These observations are assimilated into Numerical Weather Prediction (NWP) models that are used to forecast weather on synoptic time scales, and into the many long-term atmospheric reanalyses (e.g. NCEP/NCAR Reanalysis) that are used for innumerable climate studies. The impact of these in situ observations has been documented in many papers including Inoue et al. (2009), who show that the standard deviation in gridded sea level pressure (SLP) reanalyses fields over the Arctic Ocean was over 2.6 hPa in areas where there were no buoy observations to constrain the reanalyses, and this uncertainty in the SLP fields spreads to cover the entire Arctic when the observations from buoys are removed from the reanalyses. The buoy observations also help constrain of estimates of wind and heat. In situ observations of sea ice motion are also important for estimating the drift of various areas and types of sea ice, and for understanding the dynamics of ridging and rafting of this ice, which changes the thickness distribution of sea ice. Over the Arctic Ocean, this fundamental observing network is maintained by the IABP, and is a critical component of the Arctic Observing Network (AON).
The data from all USIABP buoys are released to the research and operational communities in near real-time through the WMO Global Telecommunications System. Research quality fields of ice motion, SLP, and surface temperature are also analyzed and produced by the APL-UW; these fields can be obtained from the IABP web server at http://iabp.apl.washington.edu/, and have been archived at various data centers including ACADIS.
During this presentation we will highlight the successes, advances and challenges of the IABP.
Human Dimensions of the Arctic
Articulating the Arctic: Contrasting State and Inuit Maps of the Canadian North
This paper compares four maps produced by the Canadian government, and Inuit Tapiriit Kanatami, the indigenous peoples’ organization representing Inuit living in the four recognized Inuit regions (Inuit Nunangat) of Canada, to understand the different ways in which the Arctic can be articulated as a geographic, political, and social region, and the effects this has on Northern policy and people. Our analysis is based on publicly available maps, documents, and records. After first highlighting the geographic differences in state and Inuit spatial ontologies and perceptions of the Canadian Arctic’s presumed extent, we examine the implications that different definitions of the Arctic have on indigenous peoples, northern communities, and popular understandings of the region more generally. We find that the federal government maintains a flexible definition of the Canadian Arctic as a region when in pursuit of its own policy objectives. However, when it comes to incorporating areas outside the boundaries of the three territories, particularly communities along their southern fringes, those boundaries are inflexible. The people who live in these areas, which the state considers to be outside of the Canadian Arctic, are marginalized within Arctic public policy in terms of access to federal funds, determination of land use, and a sense of social belonging to the Canadian Arctic. Our goal in this paper is to demonstrate that while most scholarly and media accounts of border conflicts in the Arctic focus on international disputes in the Arctic Ocean, national-level disputes over what constitutes ‘the Arctic’ are just as entrenched, and arguably, have a greater impact on the day-to-day lives of people who live within and just outside the region, however it is conceived.
Demographics and Climate in Arctic Alaska
The towns and villages of Arctic Alaska, most of them remote and with predominantly Alaska Native populations, have been widely described as “the front line of climate change.” They face challenges including ecosystem and living resource disruptions, thawing permafrost and shorter cold seasons affecting transportation and infrastructure, industrial development around Arctic seas, and most acutely, direct harm from shoreline erosion associated with decreased ice protection, rising sea levels, and increasing river flows. Some communities confront erosion-driven relocation or possible disasters. For these and other Arctic Alaska communities, the topic of “sustainability” is urgent on cultural and socioeconomic grounds as well as climate. As a contribution to sustainability discussions we publish a demographic database tracking yearly population, births, deaths and net migration for 43 Arctic Alaska towns and villages since 1990. These data show the widely varied paths of individual communities, along with broad trends including the upward force of natural increase, volatile effects from migration, and disproportionate outmigration by women affecting village sex ratios and life. Statistical tests detect no significant differences in the net migration rates of erosion-threatened and other communities, indicating that “climigration” (net outmigration) in response to threats is not occurring. Instead, many threatened communities’ populations are growing, and overall at a slightly faster rate than others. The lack of demographic response to foreseen but not yet disastrous physical problems may be emblematic of broader societal response to climate change, in a different sense than the “front line” discussions have meant.
Disappearing Frozen Heritage- Case studies from Scandinavia and North America
Higher temperatures, more frequent storms and loss of sea ice are all having serious negative consequences for cultural heritage. Rising global temperatures and erratic weather patterns are degrading permafrost, sea ice, glaciers and alpine ice patches. Many archaeological sites across the circumpolar north are being lost to coastal erosion, permafrost melt, and increased exposure to other elements due to reduced snow and ice protection. The rate and scale at which these archaeological contexts are disappearing means that large quantities of cultural heritage of great informational and symbolic importance to Northern communities are being lost forever.
The artefacts emerging from these frozen contexts offers us important insights into a range of topics such as subsistence, past technologies, settlement structures, land use patterns and ecological interactions. In glacial settings, snow and ice melt is exposing many ancient and historical objects in alpine regions of the circumpolar North. In Alaska, Canada and Scandinavia, large numbers of hunting tools and organic artifacts such as darts, arrows, snares and clothing have been recovered from melting ice patches by glacial archaeologists, First Nations representatives, community partners, and volunteers.
In this paper, we present case studies from alpine ice patches and coastal permafrost sites in different regions of the North. We draw attention to the information value of these fragile objects and sites for both archaeology and science in general. Finally, we outline the challenges associated with managing and monitoring these cultural heritage sites and discuss potential approaches for coping with melting heritage in the future.
Paleoecological Data from Archaeological Sites: A Rich Resource under Imminent Threat
Arctic regions contain many archaeological sites with exceptional organic preservation thanks to the frozen environment in which they were deposited and have remained. Among other things, these sites archive the residues of human subsistence activities, in stratified layers, often spanning millennia. These archives include the remains of animals and plants gathered from the surrounding area. As such, these remains represent unique sources of data on past ecosystems that can be used to track environmental change through time, and to correlate those changes with possible drivers, such as climate change, changes in human exploitation, or natural catastrophes. This can provide critical information to planners, disaster managers, fisheries and wildlife managers, and to those whose food security depends on successful harvesting of wild foods.
Arctic sites have been considered stable since archaeologists first started working in the Arctic more than 100 years ago. Today, however, the changing climate has altered the situation. As the ground warms, factors leading to decay of organic materials (bacteria, mold and chemical processes) have more time through the year to break down organic remains, leading to the disintegration of organic archives. Coastal sites are threatened by thawing permafrost, longer exposure to open water and waves, and rapidly increasing erosion. Loss rates of tens of meters per year have been recorded in some places. These valuable paleoecological archives are disappearing before our eyes. This presentation will highlight the existence of these underutilized resources and examine the effects on-going coastal processes are having on preservation of paleo-environmental archaeological archives from several contexts around the Arctic Ocean and its marginal seas.
Social Indicators Research for Arctic Communities (SIRAC)
Social and economic indicators collected by the US Census Bureau have anchored the arctic human observing system for the past four decades. Census observations provide key indicators for four of the six domains of well-being defined in the Arctic Human Development Report (AHDR) and Arctic Social Indicators (ASI) study, and in many cases represent the only source of data specifically for arctic indigenous peoples. Changes in survey design following the 2000 Census led to a substantial loss in precision, despite an increase in frequency of data collection and reporting. The higher margins of error in reported results mean that it is typically no longer possible to distinguish differences among communities or regions, or determine if conditions have changed over decadal scales for a given community or region.
The SIRAC project aims to understand sources of error and improve precision of estimates of census-derived indicators, using analysis of variance, modeling, and data assimilation techniques. The goal is to construct synthetic indicators with greater precision than the published census figures, based on both census microdata and non-census data. A key step is determining the extent that inter-annual variation limits the precision of the published figures, which are only available for small areas in the form of five-year moving averages. Initial results suggest that correlated inter-annual fluctuations in employment, income, and migration, as well as trends in slowly changing indicators such as education and language use contribute a significant portion of the overall margin of error. Statistical techniques for adjusting for these changes offer a relatively straightforward opportunity to improve precision. Other issues are more complex, however, and require a more nuanced approach.
The Arctic Data Committee: advancing polar science, research policy and society
For more than a century, the polar science community has demonstrated leadership in data management via the International Polar Year (IPY) programs beginning in 1881-1884 and other programs. Despite this historical collaboration, a coordinated, interconnected Arctic-wide system providing free, open, and timely access to high-quality data has yet to be established. There is an urgent need for the polar science community, Arctic residents, and other stakeholders to come together and develop a clear global vision, strategy, and action plan to ensure effective stewardship of and access to valuable Arctic and Antarctic data resources. In this way the unprecedented opportunities for science based on an availability of open, networked, digital, and ubiquitous communication technologies can be realized.
The International Arctic Science Committee and the Sustaining Arctic Observing Networks program formed the Arctic Data Committee (ADC) to work with partners to develop a vision and plan for arctic data. In keeping with the IASC Statement of Principles and Practices for Arctic Data Management (April 16, 2013), the ADC is working to understand the nature and structure of Arctic data systems, promote ethically open access to data, enable preservation of data through stewardship, and facilitate the interoperability of data and systems to support research and policy development by Arctic residents, decision makers and others.
During its first year the ADC has established a map of the Arctic data "ecosystem" to support policy and systems design, started the process of establishing a global protocol for sharing metadata, and supporting the community in making data more accessible through data publication and citation. We will discuss future plans established as part of international dialogue between more than one hundred researchers, northern residents, and policy makers during the Second Polar Data Forum held in October 2015.
The Communities-in-Transition in the Arctic Region (Case Study of the Sakha (Yakutia) Republic, Russia)
The paper presents the gradual inclusion of the Russian Arctic region into the global economic, social, and cultural processes, as well as explores the multifaceted challenges that the local communities-in-transition are facing (at the example of Sakha (Yakutia) Republic, Russia).
As a result of climate change, economic globalization and emergence of the new transportation routes (NSR), the local communities will be inevitably getting involved into intercultural collaboration and international cooperation, as well as into the process of transition from traditional towards modern/configurative (in terms of M. Mead) culture.
The author is focusing mainly on communities-in-transition in Sakha (Yakutia), and presenting the results of the fieldwork conducted together with Dr. Andrey Gretsov in 2013-2015. The presentation will include the socio-cultural and ethno-psychological specific features of these communities-in-transition, as well as the problems coming along with identity crisis and its consequences in search of strategies of adaptation and integration into diverse multicultural urban communities, and forms of co-existence with the global communities.
Also, the author describes the federal and regional policies in Russia that are aimed to provide comprehensive support to the peoples of the Russian North, as well as the necessity of interstate collaboration and interaction in the Arctic region and ways to resolve common problems in the field of preservation and development of the human capital in the Arctic region.
Application of High Latitude Observations and Experiments in Regional to Global Climate Modeling
Arctic observing activities to improve process-level understanding relevant to simulation of the surface energy budget
The Arctic climate appears to be in a state of evolution, as evidenced by recently observed changes to sea ice cover (Kwok and Untersteiner, 2011), permafrost depth and extent (Romanovsky et al., 2002), and the terrestrial ecosystem (Sturm et al., 2001). While the changes are noticeable, the extents to which these changes result from human activities and the potential for Arctic changes to impact the rest of the globe have yet to be quantified. To do so, a variety of numerical models are used, ranging from high-resolution, small domain models for understanding the physics associated with fundamental processes of interest, to complex climate models developed to attempt to provide information on future states and feedback mechanisms. While studies using such models have provided substantial insight, significant uncertainties remain, limiting our ability to make conclusive statements about current and future Arctic climate states.
Of these uncertainties, some of the largest involve our understanding of the exchange of energy at the surface of the Earth. Ultimately, this exchange is critical in understanding things like surface melt rates, cloud formation and plant and animal behavior. From the atmospheric perspective, correctly simulating the energy exchange is tremendously complex, as it requires accurate reproduction of cloud and aerosol properties, winds, and lower tropospheric thermodynamics. In order to improve our representation of these processes, the model community is reliant upon a variety of datasets to aid in the development and evaluation of model parameterizations.
In this presentation, I will provide an overview of a variety of non-satellite based observing systems ultimately aimed at improving our understanding of this energy exchange. This includes long-duration, process-level observations from various land-based observatories, recent aircraft (both manned and unmanned) based campaigns, and icebreaker based research campaigns. I will discuss how observations from these platforms aid in model improvement and will provide an overview of where shortcomings exist. Additionally, I will briefly touch on some exciting opportunities for providing new perspectives critical for furthering our knowledge.
Conceptualization and Initial Application of Arctic Landscape Evolution Using the Alaska Thermokarst Model
Thermokarst topography forms whenever ice-rich permafrost thaws and the ground subsides due to the volume loss when excess ground ice transitions to water. The Alaska Thermokarst Model (ATM) is a large-scale, state-and-transition model designed to simulate transitions between [non-]thermokarst landscape units, or cohorts. The ATM uses a frame-based methodology to track transitions and proportion of cohorts within a 1-km2 grid cell. In the arctic tundra environment, the ATM tracks thermokarst-related transitions between wetland tundra, graminoid tundra, shrub tundra, and thermokarst lakes. The transition from one cohort to another due to thermokarst processes can take place if thaw reaches ice-rich ground layers either due to pulse disturbance events such as a large precipitation event or fires or due to gradual active layer deepening that eventually results in penetration of the protective layer. The protective layer buffers the ice-rich soils from the land surface and is critical to determine how susceptible an area is to thermokarst degradation. Model initialization and the rate of landscape transition is based upon initial landscape classification and measurements (or observations) of ice-content, initial active layer depth, and soil properties. Many of the required data inputs are difficult to obtain due to the large spatial variability of these below ground features. In this study, we present our conceptualization and initial simulation results from the ATM model for an 1792 km2 area on the Barrow Peninsula, Alaska. The area selected for simulation is located in a polygonal tundra landscape under varying degrees of thermokarst degradation.
Evaluating Biogeochemical Change in the Arctic using Atmospheric Oxygen (O2/N2), Satellite Ocean Color Data and the CMIP5 models
Time series measurements of the O2/N2 ratio of air samples from Arctic stations have been conducted by the Scripps Institution of Oceanography since the early to mid 1990s. These time series comprise continuous geochemical records that can help quantify the magnitude of the seasonal air-sea exchanges of O2 between ocean and atmosphere, with direct relevance for understanding climate and biogeochemical changes at high latitudes.
Satellite ocean color data have been available continuously from 1997 and allow the monitoring of ocean productivity from seasonal to inter-annual time scales. The most basic surface property derived from ocean color data is the surface chlorophyll-a (Chl-a) concentration. Starting from estimates of Chl-a, higher order fields like vertically-integrated net primary production (NPP) can also be derived.
Satellite ocean color data and ground-based observations of the O2/N2 ratio of air provide independent information about the oceanic biogeochemical cycles of carbon and oxygen. Seasonal cycles in O2/N2 represent the integrated impact of air-sea oxygen fluxes across broad regions and provide a constraint on a combination of surface production and subsurface mixing processes. Ocean color data constrain near-surface biomass and productivity at high spatial resolution with near-simultaneous spatial coverage, but provide little information on subsurface processes.
Here, we will present analyses of trends in the O2/N2 seasonal cycle at sites in the Arctic. These changes will be compared to trends in productivity derived from ocean color data. Observed O2/N2 and ocean productivity will be compared to output from 8 CMIP5 Earth System Models participating in the IPCC 5th Assessment Report. CMIP5 future projections in northern high latitude ocean productivity and air-sea oxygen fluxes will also be examined.
Importance of representing heterogeneous small-scale arctic polygonal tundra in large-scale ecosystem models for reducing uncertainty in carbon balance
There are considerable uncertainties regarding the fate of arctic soil carbon with projected warming over the next century. In northern Alaska, nearly 65% of the terrestrial surface is composed of polygonal tundra, where geomorphic types (i.e. high-center polygon) disproportionately influence local surface hydrology, plant community composition, nutrient and biogeochemical cycling, over small spatial scales. Process-based biogeochemical models used for local and regional projections of ecological responses to climate change, typically operate at larger scales (1 km2-0.5°) at which fine-scale (<1 km) spatial heterogeneity is often aggregated. In this study we model change in regional carbon dynamics of fine-scale arctic polygonal tundra and determine which specific geomorphic type, group of geomorphic types, and/or spatial representation of geomorphic types are critical to consider within a large-scale modeling framework to minimize error associated with simulated spatial and temporal patterns of change. We evaluate the potential change in carbon balance from 1970 to 2100 on the Barrow Peninsula, and estimate model error/uncertainty using the terrestrial ecosystem model (DOS-TEM). We focus on two questions, (1) How might carbon dynamics of polygonal tundra on the Barrow Peninsula respond to projected warming through 2100, and (2) What is the importance of fine-scale representation polygonal tundra in large-scale regional assessments? Using the six dominant geomorphic types, DOS-TEM is extrapolated across the Barrow region, where geomorphic types and spatial resolution are iteratively grouped from 6 to 1, and coarsened from 0.0009 to 25 km2 resolution, respectively, to estimate the potential error associated with coarser spatial heterogeneity. Landscape-level simulations indicate carbon losses through ~2020, but carbon fixation recovers that lost by 2100. Model error increased substantially with coarser spatial representation of the tundra and reduced group size, where error increased ~2.3% for each 1 km² coarsening of spatial resolution. This work suggests a minimum of 2 groups (i.e. dry and wet) and maximum of 4 km2 spatial representation of polygonal tundra are necessary for minimizing error in large-scale assessments.
Observed atmospheric profiles in the Arctic Seasonal Ice Zone and the role of synoptic conditions
We use the Polar Weather Research and Forecasting (WRF) Model to simulate atmospheric conditions during the Seasonal Ice Zone Reconnaissance Surveys (SIZRS) in the summer of 2013 over the Beaufort Sea. Using atmospheric dropsonde data deployed from aircraft the performance of WRF simulations and two forcing datasets, the ECMWF Reanalysis (ERA-Interim) and the Global Forecast System (GFS), is evaluated. Observed features in the atmospheric profiles such as temperature and specific humidity inversions, and the low-level jet (LLJ) are reproduced in the mean profiles by all three models. A near-surface warm bias and a low-level moist bias are found in the ERA-Interim reanalysis. The regional model simulations using WRF significantly improve the representation of the mean LLJ, with a lower and stronger jet and a larger turning angle than the forcing. The improvement in the mean LLJ is likely related to the less efficient boundary layer diffusion in WRF than in ERA-Interim and GFS. This also explains the lower near-surface temperature in WRF compared to the forcing data set. Large differences in relative humidity between the observations, the ERA-Interim, and the GFS suggest the need to obtain more and better-calibrated humidity data in this region. We find that the sea ice concentrations in the ECMWF model are sometimes significantly underestimated due to an inappropriate thresholding mechanism. This thresholding affects both ERA-Interim and the ECMWF operational models.
The observed atmospheric profiles exhibit distinct thermodynamical states related to the synoptic conditions. Using a k-mean clustering algorithm, we identified four synoptic regimes from the ERA-Interim 3D thermodynamic and dynamic fields. The mean states of the synoptic regimes demonstrate signatures of baroclinicity and temperature advection. Their vertical profiles show significant distinction in temperature and specific humidity inversions and LLJ, which qualitatively agree with the SIZRS observations of summers from 2013 to 2015.
The Arctic and Sub-polar gyre sTate Estimate: a synthesis of observations and model
The Arctic physical environment and its ecosystems are undergoing remarkable changes. Our understanding of the driving mechanisms hinges on knowledge of the coupled Arctic ocean-sea ice’s mean state, its variability (in particular stratification and circulation), and the ability to simulate a realistic Arctic time-mean and time-varying state. Taking advantage of a growing observational database, a comprehensive synthesis of ocean hydrographic and sea ice observations in the Arctic is currently under way using the data-constrained Arctic Sub-polar gyre sTate Estimate (ASTE) for the period 2002-2014. ASTE uses the adjoint-based inverse modeling/optimal estimation tools developed within the ECCO framework to achieve a least-squares fit of a coupled ocean-sea ice model to all available satellite and in-situ observations from diverse data streams of heterogeneous spatio-temporal sampling patterns. "Best" here is defined as convergence to within data uncertainty and model representation errors while strictly following the physics encoded in model. As such, the state estimate is dynamically consistent and can be used for studies of property transformation and transport and budget analyses. Data used to constrain ASTE include hydrography and velocities from Ice Tethered Profiler (ITP) and moorings at major Arctic gateways (Bering, Davis, Fram straits), the Beaufort Gyre Exploration Project (BGEP), the Canada Basin and Nansen and Amundsen Basins Observational System (CABOS, NABOS), as well as satellite retrievals of sea ice thickness (ICESat), concentration (SSM/I), and velocities (RGPS/microwave). Examples of science applications of ASTE will be presented and include investigation of interior Arctic Ocean lateral and vertical mixing and the dominant mechanisms controlling heat, FW, and volume transports and budgets.
Understanding Arctic Processes through Delivery of Short-term Sea Ice Forecasts using the RASM-ESRL model and Validation using SeaState Observations
We will report results from our NOAA Earth System Prediction Capability (ESPC) sea ice forecasting demonstration project. ESPC is an interagency collaboration project with the goal of improving coupled model predictions from hours through to seasonal, and annual timescales.
Our project focuses on how the autumn sea ice evolution interacts with physical processes including atmospheric forcing of sea ice movement, melt, and formation through energy fluxes. For this study, we use a mesoscale, coupled atmosphere-ice-ocean mixed-layer model, termed RASM-ESRL, that was recently developed by our team from the larger-scale RASM architecture. The atmospheric component of RASM-ESRL consists of the Weather Research and Forecasting (WRF) model, the sea-ice component is the Los Alamos CICE model, and the ocean model is a single-layer ocean mixed layer.
Experimental 5-day forecasts were run daily with RASM-ESRL from early July through mid-November, 2015. This period included the ONR-sponsored SeaState field program where an array of buoys and the R/V Sikuliaq were deployed near the advancing ice edge from October 1 through November 6, 2015. Prior to the SeaState campaign, validations of the RASM-ESRL forecasts, as well as hindcasts, were completed using surface energy fluxes, rawinsondes, and remote sensor retrievals of the lower atmosphere from the Barrow, AK, and Tiksi, Siberia atmospheric observatories. During Sea State, more extensive validation data became available for many components of the air-ice-ocean system in the marginal ice zone, including detailed atmospheric structure, surface energy fluxes, ocean mixed-layer temperatures and salinity, and sea ice extent and thickness.
We will present results on the performance of various components of the RASM-ESRL coupled model, identifying aspects that are being represented well and those that still need further development. A variety of analyses will be presented that quantify the model process representations of sea-ice evolution using observations.
Ice Sheets and Glaciers
A New Stationary Radio-Echo Sounding System for cryospheric studies: Instrument Description, Results of Two Pilot Deployments, and Perspectives
Most commonly used to map ice-depth, radio-echo sounding is a useful technique in glaciology that can also provides insights into englacial properties based on the dielectric contrasts between ice, water, air, and impurities. In most studies of the cryosphere, ice-penetrating radars (IPRs) are operated as roving systems in a spatial survey. Here, we want to focus on the temporal changes an IPR can detect when used over weeks or months as a stationary, autonomous system instead. The first implementation of the instrument includes the typical components of an impulse radar system, some of them modified for medium to long term deployment: a high voltage pulser with remote fiber-optics drive control, and low mean power consumption; resistively-loaded dipole antennas; radar receiving unit equipped with an embedded controller and receiving electronics; custom on-board software to manage the radar acquisition and optimize power usage; photo-voltaic panels and controller; and a switch timer. To date, two pilot deployments took place in 2014 and 2015 in the Yukon's Saint-Elias Mountains, Canada, with the goal of obtaining englacial and subglacial signatures of a rapid lake drainage. Both years the IPR was deployed for 6 to 7 weeks and programmed to acquire data once every 3 to 4 hours. Results from these deployments will be presented. A third deployment for the monitoring of an ice-island in the arctic is underway at this time. It uses the latest implementation of the stationary IPR where a low power satellite communication modem was added to the system with related software changes to handle radar message protocol, data compression, and transmission, as well as an on-board backup power module. Proposed applications for this technology include englacial/subglacial land-based glacier monitoring, indirect detection of subglacial geothermal activity by capturing changes in basal meltwater, and ice-island decay monitoring.
Basal terraces on melting ice shelves
Ocean waters melt the margins of Antarctic and Greenland glaciers, and individual glaciers’ responses and the integrity of their ice shelves are expected to depend on the spatial distribution of melt. The bases of the ice shelves associated with Pine Island Glacier (West Antarctica) and Petermann Glacier (Greenland) have similar geometries, including kilometer-wide, hundreds-of-meter high channels oriented along and across the direction of ice flow. The channels are enhanced by, and constrain, oceanic melt. Newmeter-scale observations of basal topography reveal peculiar glaciated landscapes. Channel flanks are not smooth, but are instead stepped, with hundreds-of-meters-wide flat terraces separated by 5–50mhigh walls.Melting is shown to be modulated by the geometry: constant across each terrace, changing from one terrace to the next, and greatly enhanced on the ~45° inclinedwalls.Melting is therefore fundamentally heterogeneous and likely associated with stratification in the ice-ocean boundary layer, challenging current models of ice shelf-ocean interactions.
Monitoring seasonal variations in glacier flow in Greenland and Alaska
High rates of satellite image acquisition in the Arctic, combined with improved radiometric resolution in optical satellite imagery, makes it possible to follow relatively short-term variations in speed on all large (>1km) glaciers in Greenland and Alaska. Even in frequently cloudy areas, it is now possible to track glacier flow through much of the year. This has the potential to change our picture of ice flow variations, and will certainly improve our tracking of changes in ice sheet and glacier discharge in the future. Examples of seasonal variations and acceleration from several outlets in Greenland, and from large tidewater glaciers and surging glaciers in Alaska, will be used to show the range of flow behavior observed by this technique to date.
Monitoring supraglacial hydrologic features on the southwest Greenland Ice Sheet using Landsat-8 panchromatic imagery
The Greenland ice sheet (GrIS) has experienced extensive mass loss in recent decades and surface meltwater runoff and ice discharge are the two main causes. Meltwater runoff losses are large and have received growing attention in the last decade. Such estimates are commonly derived from surface mass balance (SMB) modeling but this approach does not consider surface meltwater routing (i.e. supraglacial rivers), storage (i.e., in supraglacial lakes), or coupling with the englacial system (i.e., moulins). Therefore, advancing meltwater transport processes in SMB models will require better understanding of supraglacial hydrologic features (lakes, rivers, moulins, and internally drained catchments), especially if they can be derived from readily available moderate-resolution satellite images. This study proposes an automatic approach to detect supraglacial hydrologic features (rivers, lakes, moulins, and internal catchments) located at southwest GrIS from Landsat-8 panchromatic imagery (spatial resolution 15 m). A total of 800 internal catchments are delineated and the average catchment area (river network length) is found to increase with elevations. In addition, moulins are found to be the prime way to drain internal catchments and the average moulin densities decrease with elevations. The pattern of these image-detected internal catchments indicates that: 1) not all the DEM-modeled topographic depressions act as meltwater sinks; 2) moulin distribution greatly impacts the internal catchment patterns; and 3) topographic depressions can be connected downstream without being fully filled, changing the fragmentary of the internal catchments. Viewing collectively, Landsat-8 satellite provides an efficiency approach to monitor supraglacial hydrologic features on the GrIS and to understand their potential impacts on ice sheet mass balance.
Ocean Melting Greenland (OMG): Investigation the impact of a warming ocean on the Greenland Ice Sheet
Global sea level rise will be one of the major environmental challenges of the 21st Century. Despite it's importance, sea level rise remains one of the most poorly predicted impacts of human-caused climate change. Most of this uncertainty stems from our inability to predict how the great ice sheets in Greenland and Antarctica, which contain ice equivalent to 80 meters of sea level, will respond to human-caused global warming. Oceans Melting Greenland (OMG) will improve estimates of sea level rise during the 21st Century observing changes in ocean circulation and glacier retreat over a five year campaign using airborne and ship-based assets. Combined with observations of the shape and depth of the sea floor around Greenland, these measurements will allow us to investigate the extent by which the oceans melting Greenland's ice from below. In this presentation we will discuss the OMG project and show some preliminary result from the
first year of the project.
The surface energy budget and the influence of clouds at Summit, Greenland
Greenland ice sheet surface temperatures and melt processes are controlled by an exchange of energy at the surface, which includes radiative, turbulent and conductive heat fluxes. In order to constrain the relevant processes, observations of all the terms are needed at once for a range of conditions and months, but opportunities for such comprehensive analyses are rare. Here, we leverage data collected by multiple projects, to calculate estimates of all the surface energy budget (SEB) terms at Summit, Greenland, for the full annual cycle from July 2013 - June 2014. The radiative fluxes are measured directly by a suite of broadband radiometers. The turbulent sensible heat flux is estimated via the bulk aerodynamic method and the turbulent latent heat flux is calculated via a two level approach using measurements at 10 and 2m. The conductive heat flux is calculated using a string of thermistors buried in the snow pack. The annual cycle and seasonal diurnal cycles of all components are investigated.
Clouds exert a strong radiative influence on the surface energy budget, warming the surface throughout the year. Generally, the other SEB terms respond to changes in net radiation, compensating for an increase in the total radiation due the presence of clouds. A case study is used to illustrate the response of surface fluxes and the boundary layer structure to the radiative influence of a low-level liquid-bearing cloud. Substantial surface warming from these clouds typically leads to the degradation of a surface-based temperature inversion and a change from a stable to unstable regime near the surface. General relationships between various cloud properties and surface fluxes are investigated at Summit for the period of 2011 through 2014.
Understanding synoptic influence on precipitation, moisture advection, and other atmospheric phenomena over Greenland
Large scale atmospheric circulation is a crucial piece to understanding both local and regional climate processes. In particular, knowledge of the effects of synoptic patterns can lead to a better interpretation of in situ measurements of local processes and has the potential to broaden our understanding of key Arctic phenomena. Using a statistical categorization technique called self-organizing maps, we classify the range of synoptic patterns that occur over Greenland into a set of states, or nodes. With this classification as a function of time it is possible to create a mathematical link between the large scale circulation on a given day and regional or local atmospheric processes. Using this method we examine the relationship between atmospheric circulation and spacial distributions of precipitation and moisture advection, as well as the effect that this has on local-scale measurements made at Summit Station, Greenland of atmospheric moisture, precipitation, and surface radiation.
Meeting the Needs of Managers and Decision-Makers
Academic Contributions for Biodiversity, Land- & Seascapes, Socio-Economics and the Atmosphere: 1,000 or so public Polar Data Sets after IPY
Academicians carry out much research in the polar regions, and many data sets are created by them world-wide. These data are crucial to inform management and efforts such as Adaptive Management, Marine Protected Areas (MPAs) etc. However, there is still a major and acknowledged lack of academic research project data readily available online in good formats and with ISO metadata; many web portals remain widely empty for submissions (Carlson 2010, 2013), or at least they remain widely underused and underfunded for their full potential. However, many of those non-contributing members of the Academic community are rather quite quick in using free climate, open access data and GIS layers when available. A huge global hunger and need for open access data clearly exist. Based on cutting-edge Data Mining synthesis projects here I show examples and provide an overview of over 1,000 Academic open access data and open source code for such cases in polar research on biodiversity, land- and sea-scapes and the atmosphere, and how such data can be delivered for a wider use, conservation management, sustainability and global impact. Arguably, a new global research attitude and science culture is consistently evolving for the three poles (Arctic, Antarctic and Hindu Kush-Himalaya) and for its associated science projects of strategic global importance, sustainability and well-being. Here a real-world outlook and vision how to cater those goals is provided from an Academic institutional perspective.
Arctic Risk Management Network: Linking Risk Management Practitioners and Researchers Across the Arctic Regions of Canada and Alaska To Improve Risk, Emergency and Disaster Preparedness and Mitigation Through Comparative Analysis and Applied Research
The Arctic Risk Management Network (ARMNet) was conceived as a trans-disciplinary hub to encourage and facilitate greater cooperation, communication and exchange among American and Canadian academics and practitioners actively engaged in the research, management and mitigation of risks, emergencies and disasters in the Arctic regions. Its aim is to assist regional decision-makers through the sharing of applied research and best practices and to support greater inter-operability and bilateral collaboration through improved networking, joint exercises, workshops, teleconferences, radio programs, and virtual communications (eg. webinars). Most importantly, ARMNet is a clearinghouse for all information related to the management of the frequent hazards of Arctic climate and geography in North America, including new and emerging challenges arising from climate change, increased maritime polar traffic and expanding economic development in the region.
ARMNet is an outcome of the Arctic Observing Network (AON) for Long Term Observations, Governance, and Management Discussions, www.arcus.org/search-program. The AON goals continue with CRIOS (www.ariesnonprofit.com/ARIESprojects.php) and coastal erosion research (www.ariesnonprofit.com/webinarCoastalErosion.php) led by the North Slope Borough Risk Management Office with assistance from ARIES (Applied Research in Environmental Sciences Nonprofit, Inc.). Funding from the US Embassy in Ottawa is making possible presentations at conferences.
The constituency for ARMNet will include all northern academics and researchers, Arctic-based corporations, First Responders (FRs), Emergency Management Offices (EMOs) and Risk Management Offices (RMOs), military, Coast Guard, northern police forces, Search and Rescue (SAR) associations, boroughs, territories and communities throughout the Arctic. This presentation will be of interest to all those engaged in Arctic affairs, describe the genesis of ARMNet and present the results of stakeholder meetings and webinars designed to guide the next stages of the Project.
Integrating the Arctic Emergency Response Management Application (ERMA) with a Community Based Observing Network (CBON)
The Arctic Environmental Response Management Application (ERMA) is an industry-standard tool developed by NOAA for enhancing oil spill preparedness and planning, assisting in coordinating emergency response efforts and improving situational awareness for human and natural disasters. The Community Observing Network for Adaptation and Security (CONAS) is a quality-assured human-sensor network that spans the Bering Strait on both the U.S. and Russian sides. CONAS acquires local-scale, near real time data on a range of global and environmental change variables, placing them in a geospatially explicit format. We propose to integrate ERMA with CONAS to develop an unprecedented means to acquire not only arctic marine domain awareness but also to place observations in a social context that can better aid preparedness and response. Specifically, CONAS observations will be assembled within the ERMA platform with appropriate data protections. This will enable a precise refinement of data interoperability protocols to take place. This initiative will be part of the Arctic Domain Awareness Center (ADAC) effort to create an intelligent system of systems by a) leveraging current best practices in maritime domain awareness, b) integrating knowledge of changing environments with the capacity to respond on the ground and c) improving cross agency collaborations in arctic maritime emergency responses as per the National Response Framework (NRF).
NWS Alaska Region Observation Program Priorities and Expansion
The National Weather Service (NWS) Alaska Region (AR) relies on a sustainable network of meteorological, hydrological, and climate observations in order to effectively provide decision support services to a broad array of users to protect life and property. However, there are significant gaps in the various observational platforms that need to be resolved that hinder the NWS AR mission. For instance, additional water level measurements are needed on the northern and western coasts of Alaska where communities are threatened by coastal erosion, storm surge, and flooding. Additional wave buoys are needed in the Beaufort Sea, Chukchi Sea, Bering Sea and Gulf of Alaska to enhance situational awareness of marine forecasters. Additional river gauges are also needed on rivers on the North Slope and in the western interior as well as southwest and eastern interior river systems where monitoring is lacking. For sea ice, the main observational needs are satellite imagery (specifically more imagery from Synthetic Aperture Radar Satellites). However, more observations are also needed from buoys to moorings, which can provide information on water temperature and salinity that and can be used to improve forecast freeze-up and break-up dates. While potential solutions have been identified, they are highly reliant on additional funding or collaboration with outside partners. This presentation will discuss the observational challenges and gaps with the goal of identifying potential links with the scientific research community that could help address our observational requirements.
Overview of the National Park Service’s Arctic Network Inventory and Monitoring Program
The National Park Service’s Arctic Network (ARCN) tracks a subset of physical, chemical and biological elements and processes of park ecosystems that are selected to represent the overall health or condition of park resources, known or hypothesized effects of stressors, or elements that have important human values. These indicators are termed “vital signs” and are part of the total suite of natural resources that park managers are directed to preserve “unimpaired for future generations.” The information synthesized by NPS and partners has applications for management decisions, research, education, and public outreach.
ARCN gathers data for Alaska’s five arctic parks: Bering Land Bridge National Preserve, Cape Krusenstern National Monument, Gates of the Arctic National Park and Preserve, Kobuk Valley National Park, and Noatak National Preserve. Collectively these units represent approximately 19.3 million acres, or roughly 25% of the land area of NPS-managed units in the United States. ARCN began in 2001 by developing conceptual ecosystem models and these models were used to select and evaluate vital signs. ARCN currently gathers and synthesizes data on 19 vital signs: Air Quality, Brown Bears, Caribou, Climate, Coastal Erosion, Dall's Sheep, Fire Extent and Severity, Lagoon Communities and Ecosystems, Lake Communities and Ecosystems, Landbirds, Muskox, Permafrost, Shallow Lakes, Snowpack, Stream Communities and Ecosystems, Terrestrial Landscape Patterns and Dynamics, Terrestrial Vegetation and Soils, Western Yellow-billed Loons, and Wet and Dry Deposition. ARCN has had excellent collaboration with the research community and seeks to expand this relationship. Examples of collaboration are: 1) using ARCN data to scale up to broader landscape analyses, 2) generating models of climate or landscape change based on existing data, 3) using wildlife or contaminants data directly in cooperation with partners for management decisions, 4) targeted research using ARCN data (e.g., critical loads of nitrogen, region-wide analysis of caribou winter range.)
What Can The Alaska Ocean Observing System Do For You?
As the Alaska regional component of the national Integrated Ocean Observing System (IOOS), the Alaska Ocean Observing System (AOOS) is directed by Congress to facilitate, implement and support ocean observing for the entire coastal ocean of Alaska, including the remote Arctic region. AOOS supports monitoring activities throughout the state, which encompasses a coastline larger than the entire seaboard of the United States combined. It accomplishes its mission by collaborating and leveraging federal, state, local and private sector partners to meet stakeholder needs for improved navigation safety, responses to coastal inundation and erosion and tracking of climate and ecosystem change and trends. AOOS supports an array of multifaceted observing activities in the Arctic, including biogeophysical year-round moorings deployed in the Chukchi Sea, wave buoys and acoustic measurements, ocean acidification sensors, marine mammal tracking gliders, and remote sensing of sea surface circulation. AOOS also helps coordinate and prioritize observing activities by facilitating working groups such as those for water level observations and for ocean acidification monitoring. The next decade of AOOS work will focus on developing decision support tools and products for users of Alaska’s marine environment including local communities and subsistence users, resource managers, private industry and others.
What if there was this place on the internet where I could find available data from the Arctic? – Introducing The Alaska Ocean Observing System’s Arctic Data Portal: Serving up Arctic Observations, Old and New
For more than 10 years, the Alaska Ocean Observing System (AOOS), representing federal, state, research, NGO and private entities, has dedicated significant resources to making observational and numerical data available digitally, graphically and for download through a one-stop Ocean Data Explorer Portal housed on the AOOS signature website--www.aoos.org. The Arctic Portal is a subset of the Ocean Data Explorer, and is dedicated solely to Arctic data resources. The AOOS Arctic Portal provides easy access to numerous sources and types of data, and offers a convenient way of viewing available assets, both current (real-time and recently collected) and historical. It is designed to help users find, access, and analyze data for planning, research, decision making and emergency response for the Arctic. The portal is equipped with a “Data Catalog” to identify available datasets and provides an interface to view and overlay multiple data layers on a map. The system includes thumbnail views of the geographic extent of each layer, the metadata, and links back to the data provider. Time series display tools also allow quick visualization of trends and climatology. New data sources of various types are being continuously added as they become available, including newly deployed real-time sensors, historical records that might be difficult to locate anywhere else, and most recently, community based knowledge from participating Alaskan Arctic subsistence villages. Without the AOOS Arctic Portal, access to such a diverse pool of information would require prior knowledge of what data assets were present and where to find them. This would be followed by visits to numerous websites that may or may not have graphical interface tools or easy access for uploading and verifying information in a unified format. A description of the types of data available and a demonstration of the Arctic Portal capabilities will be presented.