Polynyas’ Impact on Atmosphere Depends on Wind Direction
RGCM researchers study the atmospheric response to polynyas in the Southern Ocean in high-resolution climate model
Polynyas, areas of open water amidst the winter ice pack, are characterized by strong heat exchange between the ocean and atmosphere. The impact of this heat exchange on the atmosphere is studied and quantified by comparing years with and without polynyas in a high-resolution climate model.
This study is the first to address polynyas in a global high-resolution climate model, and yielded some unexpected results that motivate subsequent analysis.
The study quantified the response of several atmospheric variables to the presence of a polynya. A result that is somewhat surprising is that an increase in upward longwave radiation emitted from polynyas is exactly balanced by enhanced downward radiation from clouds; so the net longwave balance is the same for polynyas as for regular ice cover. A directional analysis showed that the atmospheric response is strongest when northeasterly winds strike over the polynya, setting up a collision between warm and moist maritime air with cold and dry katabatic winds from the Antarctic Ice Sheet.
Los Alamos National Laboratory
- Regional & Global Climate Modeling
- High-Latitude Application and Testing of Global and Regional Climate Models (HiLAT)