Arctic-Atlantic Cyclones: Variability in Thermodynamic Characteristics, Large-Scale Flow, and Local Impacts

Abstract

Cyclones at polar latitudes of the Atlantic-Arctic corridor exhibit different thermodynamic characteristics. Midlatitude-origin cyclones, which make up about 14% of wintertime cyclones in the region, are generally warm and moist. The more numerous Arctic-origin cyclones display a wide range in the boundary-layer equivalent potential temperature ${\theta }_e$ that depends on both temperature and moisture. This spread includes large positive and negative ${\theta }_e$ anomalies, leading to weak signals in composite means. Warm/moist (high-${\theta }_e$) cyclones at polar latitudes are associated with tilted and central jet regimes, steering cyclones of midlatitude-origin into the Barents region or preconditioning the environment for Arctic genesis. Conversely, cold/dry (low-${\theta }_e$) Arctic-origin cyclones form under a jet stream positioned far south, characterized by frequent southern jet regimes. These new insights into the large variability of Barents cyclones have implications for our understanding of genesis mechanisms, cyclone development, and their effect on the climate of the polar regions.