Control of Barents Sea Wintertime Cyclone Variability by Large‐Scale Atmospheric Flow

Extratropical cyclones transport heat and moisture into the Arctic, which can promote surface warming and sea ice melt. We investigate wintertime cyclone variability in the Barents Sea region to understand what controls the impacts, frequency, and path of cyclones at high latitudes. Large‐scale atmospheric conditions are found to be key, with the strongest surface warming from cyclones originating south of 60°N in the North Atlantic and steered northeastward by the upper‐level flow. Atmospheric conditions also control cyclone variability in the Barents proper: Months with many cyclones are characterized by an absence of high‐latitude blocking and enhanced local baroclinicity, due to the presence of strong upper‐level winds and a southwest‐northeast tilted jet stream more than changes in sea ice. This study confirms that Arctic cyclones exhibit large interannual variability, and accounting for this variability reveals that trends in Barents cyclone frequency are not robust over the 1979–2018 period. Plain Language Summary Extratropical cyclones traveling from the midlatitudes can cause surface warming and sea ice melt upon reaching the Arctic. Focusing on the North Atlantic, this study aims to better understand what controls the number of cyclones reaching the Barents Sea, the differences in their climate impacts, and the exact paths they take on their journey northward. We find that cyclones originating south of 60°N produce the strongest Arctic warming. The large‐scale atmospheric flow is key for steering the cyclones: more cyclones are found in the Barents Sea when the North Atlantic jet stream exhibits a pronounced southwest‐northeast tilt, while fewer cyclones are found when quasi‐stationary high‐pressure systems, referred to as “blocking” systems, form at high latitudes. No remarkable differences in sea ice conditions seem to characterize periods with many/few cyclones in the Barents Sea. The winter‐to‐winter variability in the number of Arctic cyclones is large, and no robust trends are observed over the last 40 years. Key Points The temperature and moisture signature of cyclones depends on their origin and path more than their strength Jet stream and blocking play a primary role in the development and path of Arctic cyclones Arctic cyclone frequency exhibits large interannual variability and nonrobust trends