Effects of Extreme Arctic Sea Ice Anomalies on the Northern Hemisphere Atmosphere During Early Winter

Substantial decreases in Northern Hemisphere summer sea ice extent have occurred over the past several decades. We present an analysis of the influence of declining Arctic sea ice cover on the atmosphere, specifically during the autumn/early winter following an extreme summer minimum event. Statistically robust ensemble simulations from the Weather Research and Forecast Model Advanced Research WRF (v 3.0.1) are used to compare the atmospheric response for the case of the extreme sea ice minimum of 2007 to the corresponding response for the more typical ice conditions of 1984 - the year with median ice extent for the 1979-2008 satellite era. As the area of open water increases, it leads to increases in the amount of heat and moisture transferred from the Arctic Ocean to the atmosphere during the subsequent autumn. During late autumn and early winter of 2007, these fluxes rival those found in regions such as the Great Lakes and the Gulf Stream. We emphasize the impacts of this heat and moisture transfer on polar airmass formation and thus Northern Hemisphere land temperatures in subpolar latitudes.