GRACE Results and Their Impact: Climate Change in Siberia and Northern Canada and the Freshening of the Arctic Ocean

Discharges from the land masses surrounding the Arctic Ocean form a key component of its freshwater budget, which in turn plays a critical role in regulating its internal dynamics. Especially during summer, runoff from the Yenisey, Lena and Kolyma basins in Siberia, and the Mackenzie basin in Canada, leads to the formation of a cold Arctic halocline near the surface which strongly impacts the processes of vertical mixing and sea ice formation. To understand the impacts of global change on these processes, therefore, it is critical to gain an accurate assessment of freshwater inputs to the Artic Ocean and their changes as the climate warms. Due to its high orbital inclination and low altitude, the GRACE constellation provides comprehensive geographical coverage, on length scales sufficiently small to resolve the individual catchment basins that provide a major source of freshwater to the Arctic Ocean. Here we explore the impact of GRACE data on tracking changes in Arctic freshwater runoff and its sources, using comparisons with estimated river discharge and net precipitation to form water mass budgets for the individual basins listed above. Changes on both seasonal and interannual timescales will be investigated.