Planetary and synoptic scale adjustment of the Arctic atmosphere to sea ice cover changes

Abstract

By means of unforced simulations with a global coupled circulation model it is shown that naturally occurring changes between high and low sea ice cover phases of the Arctic Ocean exert a strong influence on the Northern Hemisphere storm tracks. This work emphasizes on the nonlinear dynamical feedback between Arctic sea ice cover and the Arctic Oscillation (AO) like atmospheric response in dependence of the wintertime sea ice distribution. Two seven year long time slices with high and low sea ice cover have been analyzed with respect to the feedbacks between the time-mean flow, the quasi-stationary planetary and the baroclinic waves. The wave energy fluxes on time scales 2 to 6 days increase in the middle troposphere between 30 and 60° N during the high sea ice phase and enhance the zonal wind. Their increase is compensated by a strong reduction in the Eliassen-21 Palm fluxes on time scales from 10 to 90 days between 60 and 70° N during high sea ice phases, accompanied by reduced zonal winds. High sea ice cover phases are related to the zonal wind changes during the positive phases of the AO especially over the northern part of the Atlantic Ocean.