Response of Northern Hemisphere Mid- and High- Latitude Storm Activities to Arctic Sea Ice Forcing: A Modeling Investigation

Arctic sea ice has exhibited a rapid reduction and large fluctuations during recent decades in conjunction with a warming climate. To identify sea ice impacts on extratropical storm tracks and associated surface climate, we employed the NCAR's Community Atmosphere Model to conduct a suite of sensitivity experiments, in which the model is solely forced with observed time-varying sea-ice concentration from 1979 to 2008. A storm identification and tracking algorithm was applied for analyzing variability of and changes in storm activities simulated by the model. The results show that reduced sea-ice cover enhances Arctic storm activity and increases warm moist air advection into the Arctic. As a consequence, Arctic surface air temperature (SAT) throughout the year and precipitation in spring, summer and fall seasons increase. By contrast, storm activity weakens and anticyclones strengthen over Eurasia. The strengthened anticyclones lead to a decrease in cloud cover, precipitation and SATs in both fall and winter seasons. These findings also suggest that Arctic sea ice not only impacts local, but also lower latitude weathers and climate.