INTRODUCTION AND OVERVIEW
We received 9 contributions to the June Regional Outlook report. The regional contributions this month suggest that ice conditions will be below normal relative to the past two to three decades, and that they may potentially rival the 2007 record minimum if multi-year ice at lower latitudes melts back early in the season.
Regional Outlook contributions can help shed light on the uncertainties associated with the estimates in the Pan-Arctic Outlook by providing more detail at the regional scale. In addition, the persistence of regional features (such as above-normal multi-year ice concentrations compared to recent years in the southern Beaufort and Chukchi Seas) and geographic constraints (such as the confinement of ice in the Canadian Arctic Archipelago) can lend predictive skill to forecasts.
In contrast with the June Pan-Arctic Outlook estimates, which show a greater range of predicted values, the Regional Outlook contributions are more in line with each other than last year. For example, in the Northwest Passage, empirical, statistical, and numerical modeling approaches yield a consistent picture of remnant ice and lack of completely open conditions, in contrast with last year when two methods diverged in the predictions.
Forecasts based on the statistics of past summer ice for the different regions provide us with a framework to evaluate whether the ice cover behaves in a similar fashion as in the past or whether the present year is anomalous. For example, lingering multi-year ice not accounted for in some of the models may delay the retreat of the ice edge towards the North. Ice retreat depends strongly on the amount of solar heating of the surface ice and ocean; clear sky conditions early in the melt season can go a long ways towards helping ice retreat later in the season, so this is one of the variables that will be monitored closely (e.g., in the Barrow coastal sea ice break-up forecast, see below). Ship observations will also help evaluate this important factor this season.
Definitions of sea ice terminology can be found in our Sea Ice Outlook Glossary.
SUMMARY LIST OF REGIONAL FORECASTS
- Howell and Agnew – closed
- Zhang – closed
- Tivy – closed
Beaufort / Chukchi Seas:
- Maslanik, Tivy, Pokrovsky – below-normal ice area overall, but high concentration may remain along the coast in the southern Beaufort and Chukchi Seas
- Zhang – ice edge further north than in 2009
- Petrich and others – too early in the season to use 16-day weather forecasts to predict fast ice break-up around Barrow
- Lindsay and Zhang – below-normal ice cover, ice characteristics governing navigation comparable to 2007 and 2009
East Siberian / Laptev Seas:
- Zhang, Tivy – below-normal ice cover but greater than 2009
Barents / Kara / Greenland Seas:
- Zhang – ice edge further north than in 2009
- Gerland – less ice around Svalbard compared to 2009
- Pokrovsky – below-normal ice cover
- Tivy (Greenland Sea) – below-normal ice cover and less than 2009
- Tivy (Kara and Barents Seas) – below-normal ice cover but comparable to 2009
Canadian Arctic Archipelago:
- Tivy – below-normal ice cover, slight increase from last year
- Gudmandsen - unstable ice barrier in Nares Strait, likely more inflow of old ice into Baffin Bay than last year
BEAUFORT / CHUKCHI SEAS
An estimate of ice age at the end of April is shown in Figure 1. This image was provided by Maslanik and is a University of Colorado satellite-derived sea ice age product. The lobe of old ice extending through the Beaufort Sea and into the Chukchi Sea is estimated to be >5 years old. Aerial thickness surveys and ground-based sampling in the western Beaufort and eastern Chukchi Sea in April this year indicate that level ice in the region is well over 3 m thick and strong (due to low salt content; www.sizonet.org). The outlook submitted by Maslanik based on this distribution of multi-year ice predicts that the lobe of multi-year ice will persist later into the melt season and the first-year ice to the north will melt out earlier, yielding a “semi polynya” of open water/low concentration ice partially surrounded by multi-year ice into late summer.
Figure 1. Estimated ice age at the end of April for 2010 from the University of Colorado satellite-derived (Lagrangian drift) sea ice age. Warmer colors indicate older ice. (Maslanik).
A statistical forecast, based on canonical correlation analysis and using fall surface air temperature anomalies over the Beaufort Sea as the predictor for September sea ice concentration (Figure 2) submitted by Tivy, shows a high probability of above-normal ice concentrations in the southern Beaufort Sea and a high probability of below-normal ice concentrations slightly north of the region of first-year ice in Figure 1. This is to some degree consistent with the Maslanik outlook based on the distribution of multi-year ice.
Figure 2. Probabilistic forecast of September 2010 sea ice concentration anomalies. The three categories are equiprobable based on the 1981–2006 training period. The predictor is fall (Oct-Nov-Dec) surface air temperature over the Beaufort Sea region. (Tivy)
The outlook submitted by Pokrovsky also points to more ice in the southern Beaufort Sea compared to previous years. A positive winter Pacific Decadal Oscillation (PDO) index and associated low sea-surface temperature (SST) anomalies in the North Pacific are expected to slow summer sea ice melt in the coastal Beaufort and Chukchi Seas due to colder than normal Pacific water inflow.
In contrast, the ensemble forecast from a coupled ice-ocean model submitted by Zhang shows the September ice edge further north than in 2009 (Figure 1, East Siberian / Laptev Sea region). The ice-ocean model is initialized with satellite estimates of ice concentration and model-simulated ice thickness and ocean fields, and is forced by the atmospheric fields from 2003 to 2009. Hence, as a probabilistic estimate, some of the empirical evidence entering into the other outlooks may not impact ensemble simulations to the same degree.
A prediction for the date of break-up of fast ice along the coast of Barrow was submitted by Petrich and others. Their prediction is based on the quantity of incoming solar radiation and uses 16-day forecasts from a numerical weather prediction model (WRF). The most recent 16-day weather forecast does not yet reach far enough into the future to predict break-up, but the forecast will be updated for the July Outlook. However, observations and forecasts suggest a slightly earlier break-up than normal.
Figure 3. Empirical model for predicting the break-up of landfast sea ice along the coast of Barrow, Alaska. The model is based on data from 2002 to 2009. (Petrich and others)
Lindsay and Zhang (see also their website at http://psc.apl.washington.edu/lindsay/Alaskan_summer_ice.html) submitted a forecast for the 11 shipping-specific sea ice parameters near Barrow, Alaska that are included in the "Seasonal Outlook for North American Arctic Waters'" issued by the North American Ice Service. Their prediction uses output from the Zhang coupled ice-ocean model as predictors in a statistical regression-based model. All 11 predictions point to below-normal ice conditions. There is a 50% or greater chance of record minimum ice conditions for 7 of the 11 parameters, so a new record minimum in some of them is likely. They predict a July 3rd opening of the sea route into Prudhoe Bay (less than 5-tenths ice) and 95 days of ice-free conditions along the shipping route.
EAST SIBERIAN / LAPTEV SEAS
Sea ice in the East Siberian and Laptev Seas is predominantly first-year ice (Beaufort Sea Region, Figure 1). The ensemble prediction from a coupled ice-ocean model submitted by Zhang shows considerably more ice in the East Siberian Sea compared to 2009. The ice-ocean model is initialized with satellite estimates of ice concentration, model-simulated ice thickness, and ocean temperature/salinity fields and is forced by the atmospheric fields from 2003 to 2009. This is somewhat consistent with the two statistical forecasts submitted by Tivy. The predicted September sea ice area in the East Siberian and Laptev Seas, from a simple regression model using summer (Aug-Sep-Oct) sea surface temperatures in the North Atlantic as the predictor, is below normal but greater than in 2009. The probabilistic forecast shown in Figure 5, using winter (Jan-Feb-Mar) North Atlantic sea surface temperature as the predictor, predicts a high probability of above-normal ice concentrations along the coast.
Figure 4. Ensemble prediction of September 2010 sea ice thickness. The white line represents the satellite observed September 2009 ice edge defined as the 15% ice concentration contour while the black line is the model-predicted September 2010 ice edge. (Zhang)
Figure 5. Probabilistic forecast of September 2010 sea ice concentration anomalies. The three categories are equiprobable based on the 1981-2006 training period. The predictor is winter (Jan-Feb-Mar) North Atlantic sea surface temperature. (Tivy)
BARENTS / KARA / GREENLAND SEAS
Barents and Kara Seas are predominantly first-year ice, whereas significant quantities of multi-year ice are present along the coast of the Greenland Sea as it is being exported from the Arctic Ocean (Figure 6, Beaufort / Chukchi Sea region). The May 2010 ice edge shown in red in Figure 6 is compared against the location of the ice edge in the past three years. This year, the ice edge is the furthest south in the south Greenland Sea and the furthest north in the north Greenland Sea, as compared to the past three years. In the Barents Sea, between Svalbard and Novaya Zemlya, the ice edge this year is the furthest, while more ice is visible in the southeastern Barents Sea.
Figure 6. Ice extent (monthly means, May) southern border of 30% ice concentration in the Greenland Sea / Fram Strait and Barents Sea, based on passive microwave satellite data (red = May 2010, orange = May 2009, green = May 2008, blue = May 2007). (Gerland)
Gerland and others speculate that it is the influence of the Atlantic water that controls the position of the ice edge. This is in agreement with Pokrovsky who predicts below-normal ice cover in the Atlantic sector of the Arctic Ocean, based on observed warm spring sea surface temperature anomalies in the northeast Atlantic Ocean.
The ensemble model prediction submitted by Zhang shows a complete retreat of the ice edge in the Barents, Kara, and Greenland Seas (Figure 1, East Siberian / Laptev Sea region) and the ice extent is considerably less than in 2009. The ice-ocean model is initialized with satellite estimates of ice concentration and model-simulated ice thickness and ocean fields, and is forced by the atmospheric fields from 2003 to 2009.
Gerland and others also point to a reduction in ice extent compared to last year due, in part, to above-normal sea surface temperature anomalies in the North Atlantic. A regression-based forecast for September ice extent around Svalbard (an area extending from 72–85N and 0–40E), which uses May sea surface temperatures, the March index of the Arctic Oscillation, and April ice conditions as predictors, yielded a mean ice extent in September 2010 of 255,788 square kilometers around Svalbard. This forecast estimate ranks 9th in the record of September ice extents (1967–present).
The regression-based forecast submitted by Tivy for the Greenland Sea (Figure 7) also shows a reduction in September sea ice area compared to 2009 based on fall (Sep-Oct-Nov) sea surface temperature anomalies in the North Atlantic. However, the regression-based forecast for the Barents / Kara Seas is not consistent with the other outlooks (Figure 7). The September ice area is predicted to be comparable to 2009 based on winter (Jan-Feb-Mar) sea level pressure anomalies over the Kara and Laptev Seas.
Figure 7 (Tivy). Regression-based forecasts for the 2010 Barents / Kara Seas and Greenland Sea September ice area. The models are trained on the 27-year period from 1981-2006 (dark red) and independent forecasts were generated for 2007-2010 (red); actual values are shown in black. The predictor for the Barents/Kara seas is winter (Jan-Feb-Mar) sea level pressure over the Kara and Laptev Seas; the predictor for the Greenland Sea is fall (Sept-Oct-Nov) sea surface temperature in the North Atlantic. Click to enlarge figure.
CANADIAN ARCTIC ARCHIPELAGO (CAA)
In the pre-season outlook submitted by Tivy, a simple regression model is used to predict the September sea ice area in the Canadian Arctic Archipelago (Figure 8). The predictor is multi-year ice anomalies in the Beaufort Sea along the coast of the islands the previous summer (14-month lead), which is an area of ice import into the CAA. The model predicts below-normal ice area compared to the long-term mean and only a slight increase compared to 2009. Spatial forecasts from both a statistical model submitted by Tivy and a dynamical model submitted by Zhang are discussed in the following section on the Northwest Passage.
Figure 8. (Tivy). Regression-based forecasts for the 2010 Canadian Arctic Archipelago September ice area. The model is trained on the 27-year period from 1981–2006 (dark red) and independent forecasts.
NORTHWEST PASSAGE (NWP)
At the beginning of May, multi-year ice concentrations in the Western Parry Channel region of the Northwest Passage (Figure 9) were only slightly above the record low in 1999 and less than in 2007, when the region cleared for the first time during the satellite era. However, all three outlooks for this region indicate that some ice will remain in the NWP in September.
Howell and Agnew make the point that the ice in the NWP and the surrounding regions is mobile during the summer, and as a result the spatial distribution of multi-year ice at the beginning of the season can be used to predict whether or not the NWP could be ice-free in September. This year, Howell and Agnew suggest that high concentrations of multi-year ice in M’Clintock Channel (Figure 9) will likely delay breakup in this region and keep multi-year ice concentrations high in Western Parry Channel as ice is transported southward during the summer.
Figure 9. Spatial distribution of multi-year ice (in tenths) within the Western Parry Channel region of the Northwest Passage on May 1st for a heavy ice year (2004), a light year ice (1999), clearing year (2007), last year (2009), and 2010. Data is from the Canadian Ice Service. (Howell and Agnew)
In an ensemble prediction from an ice-ocean model, Zhang shows ice remaining in the Eastern Parry Channel in September (Figure 10). The ice-ocean model is initialized with satellite estimates of ice concentration and model simulated ice thickness and ocean fields and is forced by the atmospheric fields from 2003 to 2009.
Figure 10. Ensemble prediction of September 2010 sea ice thickness in the Northwest Passage region. (Zhang)
Using a statistical model based on winter near-global sea surface temperatures, Tivy shows high concentrations of ice remaining throughout the NWP region. The model, which uses Canonical Correlation Analysis to describe linear relationships between predictors and predictands, is used in both Canada and the United States for seasonal predictions of temperature and precipitation.
Gudmandsen provides a more detailed analysis of ice export from the Lincoln Sea north of the Canadian Arctic Archipelago into Baffin Bay, through Nares Strait between Greenland and Canada. In contrast with last year he notes that episodes of ice export, stopped by formation of temporary ice bridges, led to an influx of multiyear ice into Nares Strait, which will slow down melt and ice retreat later in the season.
Figure 11. Prediction of September 2010 sea ice concentration in the Canadian Arctic Archipelago from a statistical model (canonical correlation analysis). The predictor is winter (Jan-Feb-Mar) near global sea surface temperature. (Tivy)
HUDSON BAY AND THE ARCTIC BRIDGE
By September, the Hudson Bay region is generally ice-free. Tivy submitted an outlook for July ice concentration anomalies in Hudson Bay. July is the main transition month between ice-covered and ice-free conditions and it is a month of particular interest, since the mean opening date for the shipping route to Churchill is July 25th. Using a statistical model based on canonical correlation analysis with fall sea surface temperature anomalies in the North Atlantic as the main predictor, Tivy shows below-normal ice concentrations throughout most of the region (Figure 12), which suggests an earlier-than-normal opening of the shipping season.
Figure 12. Prediction of July 2010 sea ice concentration anomalies in the Hudson Bay region from a statistical model. (Tivy)
INDIVIDUAL COMMUNITY OUTLOOK SUBMISSIONS