Diabatic processes in very long summer Arctic cyclones

Arctic cyclones are synoptic-scale atmospheric low pressure systems that spend the largest part of their lifetime in the Arctic region. As they are associated with strong surface winds and precipitation, their impacts can be important on local populations or ecosystems. In summer, Arctic cyclones can be quite long and are typically cold-core cyclones associated to a tropopause polar vortex above them. Some of these cyclones last more than a month during which their interaction with sea ice might be damaging by enhancing its melting, that is why a focus was made in the recent years on these extremes. The reasons for the longevity of such cyclones are not clear yet and motivate the present study. Our approach consists in studying a single Arctic cyclone of August 2022 as an example and then tracking all summer Arctic cyclones in ERA5 reanalysis. The tracks are separated into different categories (cold-core vs. warm-core or long vs. short) using a newly developed cyclone phase space. Processes maintaining or destroying the structure of the different categories of cyclones are investigated by performing an energetic budget and a potential vorticity (PV) budget. A particular attention is paid on diabatic and frictional processes maintaining or destroying PV at different levels.