Abstract
Arctic cyclones play a crucial role in Arctic weather and climate. It has been shown that Arctic cyclones of different origins have different structural characteristics. In this study, we examine the contributions of Arctic cyclones of polar origin (ACPs) and midlatitude origin (ACMs) to poleward heat transport in the Arctic using a cyclone track dataset and ERA5 reanalysis from 1979-2021. We found that ACMs are associated with stronger poleward heat transport per cyclone than ACPs due to their structural differences. The eddy component of heat transport along a latitude circle dominates over the mean component and is enhanced during years of high AC activity. Notably, ACM activity is concentrated over the Nordic Seas and is significantly correlated to the variations of heat transport in winter, while the variability of ACP activity is associated with the changes of the Arctic frontal zone and is significantly correlated to the variations of heat transport in summer. The variations in ACP and ACM activity are associated with different environmental conditions: active ACM winters are associated with a stronger zonal jet over the subpolar regions, particularly across the North Atlantic, while active ACP summers are characterized by a stronger Arctic jet. Furthermore, poleward heat transport by the mean flow is enhanced significantly between 60° - 80° N during years of high AC activity in both summer and winter. Additionally, a negative correlation exists in the seasonal frequencies of ACPs and ACMs in summer and autumn, indicating the compensation between the heat transport by ACPs and ACMs.
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