Limited Overall Impact of Cyclones on Arctic Sea Ice Tendencies throughout All Seasons

Le résumé fourni par la source

Abstract Previous work documented both strongly positive and strongly negative impacts of cyclones on sea ice, with differing conclusions on their overall effect. To better quantify this effect, we attribute sea ice tendencies to cyclones and other weather features in a long-term pan-Arctic simulation with the next-generation sea-ice model (neXtSIM). We find the net impact of cyclones on the Arctic sea ice to remain small, although cyclones can locally and instantaneously strongly affect sea ice. This result is due to a combination of cyclones occurring relatively infrequently and many other processes affecting sea ice also in the absence of cyclones. In contrast to previous studies, we find the weakest impact of cyclones on sea ice during summer. We further show that focusing on different types of midlatitude weather systems in the Arctic captures a more nuanced impact on sea ice, with fronts or pronounced moisture transport having a stronger impact on sea ice than cyclones, in particular during winter. Even though fronts and moisture transport do not necessarily occur independently of cyclones, they highlight different aspects and sometimes extend significantly beyond the area associated with cyclones. Climatologically, however, the impact of fronts and moisture transport axes remains small because these features occur even less frequently than cyclones. Finally, we show that cyclones have a stronger impact on sea ice concentration than sea ice thickness. Significance Statement Cyclones can have strongly positive and negative effects on sea ice. On the one hand, they are often associated with strong wind and warm air, causing melt both at the surface and by mixing up warmer waters from below. On the other hand, the colder air in the cold sector can accelerate sea ice formation. In addition, the wind associated with a cyclone can spatially redistribute the ice thickness. Previous work has come to different conclusions on which processes dominate the overall impact. We show that the vast majority of the sea ice changes in the Arctic over four recent decades occurred in the absence of cyclones. Cyclones had a weak net-negative impact on sea ice, which was least pronounced during summer.

Ce résumé expose les affirmations des auteurs. BNTIC ne l’interprète pas comme une validation indépendante des résultats.