Influence of the Arctic Frontal Zone on Summer Cyclone Activity and Precipitation in the Central Arctic Ocean

Abstract:

Cyclones are a crucial component of the Arctic climate system, acting as a key mechanism by which the atmosphere redistributes energy and moisture from lower latitudes. In the central Arctic Ocean (CAO), cyclone activity reaches its peak in summer, which has previously been related to cyclogenesis along the Eurasian continent. The seasonal presence of strong horizontal temperature gradients along the Arctic coastline (the Arctic frontal zone or AFZ) has also been suggested as a source of summer cyclones for the CAO; however, this hypothesis has always been considered as a part of larger studies and has not yet been closely examined with focused research.

This study incorporates data from NASA’s Modern Era Retrospective Analysis for Research and Applications (MERRA) and a cyclone detection and tracking algorithm to critically evaluate the relationship between the summer AFZ and cyclone activity in the CAO. By analyzing both individual cyclones and monthly fields of cyclone characteristics, we find that the AFZ is not a region of cyclogenesis, but rather cyclone intensification for systems forming on the leeward side of several Siberian mountain ranges. As they propagate into the CAO, these cyclones experience greater deepening when the horizontal temperature gradients of the AFZ are stronger. On a broader scale, we show that the intensity of the summer AFZ has a positive correlation with mid-tropospheric Eady growth rate, cyclone intensity, cyclone frequency, and total precipitation in the CAO during summer. This relationship remains even when controlling for variability in large-scale circulation (the seasonally varying Northern Annular Mode). Taken as a whole, these findings demonstrate the importance of the summer Arctic frontal zone as an intensifier of energy and moisture cycles for the Arctic Ocean.