Moisture Flux Estimates Derived from EOS Aqua Data in the Arctic

Abstract

The Arctic sea ice acts as a barrier between the ocean and atmosphere inhibiting the exchange of heat, momentum, and moisture. Recently, the ice pack has been decreasing in area and concentration. This diminished sea ice coverage could potentially allow for larger moisture fluxes that affect surface energy budgets, the occurrence of clouds, and the near-surface humidity and temperature. Currently, reanalyses are known to produce large errors and biases in the Arctic, warranting improved moisture flux algorithms and input data. Using the Monin-Obukhov similarity theory, with adjustments made to better suit the conditions of the Arctic, and observations from NASA's EOS Aqua satellite, specifically the AIRS and AMSR-E instruments, the daily moisture flux is calculated from 2003-2011. The moisture flux is studied for a series of North Water polynya events between 2003-2009 to test the accuracy of the Aqua products and our algorithm. Using in situ data we validated moisture flux results, finding an error of 20.3%, improving the moisture flux accuracy compared to other climate models. The moisture flux for the entire Arctic was studied to look for inter-annual variations and was compared to changes in the sea ice. Instead of an expected increase in the moisture flux due to a declining sea ice pack, there has been a 15% decrease. On a regional scale and based on their average moisture flux, the Chukchi/Beaufort Seas, Laptev/E. Siberian Seas, Canadian Archipelago and Central Arctic are increasing, between 2.1 and 4.8 %/yr. Increases are due to the changes in the ice concentration, which allows for the surface temperatures to increase substantially in the fall and winter months when the amount of moisture exchanged is highest. The Kara/Barents Seas, E. Greenland Sea and Baffin Bay are decreasing, between 0.53 and 9.2 %/yr. These regions have areas of open water year round, and their exchanges of moisture are due mostly to smaller differences in surface and 2 m specific humidities. The contribution of the sea ice zone to the total moisture flux (from the open ocean and sea ice zone) has increased by 3.6% because the amount of open water within the sea ice zone has increased by 4.3%.