Wednesday 24 Apr 2019: Atmospheric response to Arctic sea ice decline in global climate model experiments: sensitivity to the sea ice pattern and experimental set up
Rym Msadek - CERFACS
Satellite observations indicate that Arctic sea ice has decreased by more than 14% per decade since the 1970s, a decline that is projected to continue in the future according to climate model simulations. The possible influence of this sea ice reduction on midlatitude weather and climate has raised a lot of scientific interest. However, detecting an influence of sea ice reduction on atmospheric circulation in observations is difficult because of the large internal variability. In this presentation we investigate the atmospheric response to Arctic sea ice reduction using global climate model simulations driven by idealised sea ice forcing. We compare the atmospheric response to an abrupt melt of summer Arctic sea ice to that driven by a more moderate, yet strong sea ice perturbation, corresponding to a projected global mean warming of +2șC. In both experiments we find a strengthening of the winter polar vortex in response to sea ice decline, but we show marked differences in the tropospheric response in terms of wind pattern and magnitude, as well in the temperature response over land. We stress the importance of coordinated model experiments to determine the robustness of the atmospheric response to sea ice decline.