An Observational Array for High Resolution, Year-Round Measurements of Volume, Freshwater, and Ice Flux Variability in Davis Strait

This study will use an integrated observing system that will provide year-round measurements of volume, liquid freshwater and ice fluxes across Davis Strait. Fluxes through the Strait represent the net integrated Canadian Archipelago through flow, modified by terrestrial inputs and oceanic processes during its southward transit through Baffin Bay. This study will be part of a coordinated international effort to quantify (and eventually monitor) the variability of fluxes connecting the Arctic and Atlantic Oceans and to understand the role played by the Arctic and sub-Arctic in steering decadal scale climate variability. The system will employ complementary techniques, combining mature technologies with recent developments in autonomous gliders (presently undertaking their first extended science missions) to address all aspects of flow through Davis Strait, including some measurements that have not previously been technologically feasible. The components of the proposed system include: A sparse array of subsurface moorings, each instrumented with an upward looking sonar, an Acoustic Doppler Current Profiler (ADCP) and a single conductivity-temperature (CT) sensor. These will provide a time series of upper ocean currents, ice velocity and ice thickness. These measurements will then be used to estimate the ice component of freshwater flux, provide an absolute velocity reference for geostrophic shears calculated from Seaglider hydrographic sections, and derive error estimates for lower-frequency flux calculations. Trawl and iceberg resistant bottom landers, instrumented with ADCPs and CT sensors, will be deployed across the Baffin and Greenland shelves to quantify variability associated with strong, narrow coastal flows. Acoustically navigated Seagliders will provide year-round, repeated, high-resolution hydrographic sections across the Strait. The combination of emerging and existing technologies implemented in the observing system may serve as a prototype for accurate long-term monitoring of freshwater and ice fluxes in high latitude environments subject to seasonal or permanent ice cover. Acoustically navigated autonomous gliders capable of extended missions in ice covered environments will provide a significant new observational tool, opening important regions of high latitude oceans to intensive measurement programs.