Detecting Seasonality and Regionality of Changes in Arctic Storm Activity

Recent studies have indicated a poleward shift of storm track in the northern hemisphere and an intensification of storm activity in the Arctic Ocean. The Arctic Ocean has complex geographic features with a large area of shelf seas and deep basins, which presents complex seasonally- and regionally-dependent thermodynamic characteristics. For example, the Eurasian and Canada Basins are covered by perennial sea ice, while sea ice retreats in summer over the large area of the Eurasian and Alaskan shelf seas. The latter leads to an exposure of ocean directly to atmosphere and an enhancement of air-sea interaction. In this study, we followed our previous, which mainly investigated variability of and long-term changes in an overall storm activity over the entire northern hemisphere and the Arctic region, to examine seasonally- and regionally-dependent changes in storm activity in the Arctic Ocean. We divided the entire Arctic Ocean into 12 sub-regions, representing different geographic areas with different underlying sea ice and hydrographic properties. The results demonstrate new details of storm activity compared with the previous overall analysis, indicating the summer maximum storm activity mainly occurring over the Pacific-side Arctic deep ocean and shelf seas and the long- term intensification occurring over the North Atlantic-side Arctic basins and shelf seas. The largest amplification of the storm activity around 1990, consistent with the amplified Arctic Oscillation, occurs over the Canadian Basin, rather than the whole Arctic domain.