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

Abstract

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.

Trends and variability in polar sea ice, global atmospheric circulations, and baroclinicity

“…Among these are the "eddy-mean flow" interactions, [76][77][78] which highlight the intimate association between atmospheric eddies, on daily and longer time scales, and the "mean" climate. 79,80 Indeed, transient synoptic systems are central to the workings of the climate system. In particular, they are fundamental to effecting the meridional transports of energy and momentum that are required to balance the various global budgets, particularly in the SH.…”

Nordic Seas Heat Loss, Atlantic Inflow, and Arctic Sea Ice Cover Over the Last Century

“…Such air streams are typically associated with atmospheric blocking events (Woods et al., 2013), or sequences of extratropical cyclones (Binder et al., 2017; Messori et al., 2018). However, the exact relationship between the synoptic and large‐scale circulation features that drive heat and moisture transport to the Arctic remains a topic of active research (Madonna et al., 2020; Papritz & Dunn‐Sigouin, 2020). Consequently, the atmospheric meridional heat transport distribution is strongly skewed, with a few intense events contributing a considerable fraction of the seasonal average transport (Messori et al., 2017).…”

Diabatic effects on the evolution of storm tracks

“…We also use the cold air outbreak (CAO) index (as defined in Papritz and Spengler, 2017) and cyclone tracks identified through the University of Melbourne algorithm (Murray and Simmonds, 1991a, b), where we require a minimum duration of at least five 6-hourly steps. For reference, the same tracks were used in Madonna et al (2020) and Tsopouridis et al (2021), where additional selection criteria were applied for their analysis.…”