On the Relationship of Arctic Polynyas and Atmospheric Rivers. Analyzing Arctic polynya and atmospheric river activity during winter seasons between 1979 and 2019

Sammanfattning

Atmospheric rivers [ARs] are narrow and long regions characterized by unusually high moisturetransport. ARs have over the last decades experienced a poleward shift and are because of thisbecoming more important to study in the higher latitudes. Arctic polynyas, openings in the sea icecover, have simultaneously increased in frequency. However, the effect of ARs on arctic polynyashave not been sufficiently studied. In this study, we investigate the potential relationship betweenARs and Arctic polynyas.Using a public dataset based on satellite data and one AR-catalogue from the ARTMIP project,we retrieved polynya and AR activity for the winter seasons between 1979 and 2019. Initially,an Arctic-wide analysis was made. We analyzed the general characteristics of ARs and polynyasindependent of their location. Then we examined the relationship between ARs and polynyaopening events, here defined as the polynya variable changing from closed to open for any gridcell. Subsequently, we identified nine regions with high polynya activity and conducted a similaranalysis for these individually.Our results show a positive correlation (r ≈ 0.49) between AR frequency and polynya openingevents across the Arctic. Over a period of four days before the opening, ARs are present duringapproximately 36% of polynya opening events. This is a substantial increase compared to thebaseline AR occurrence, which is almost 7%. The relationship between ARs and polynya openingsis strongest one day prior to the opening event.The regional analysis reveals high variability, with five out of nine regions showing positive correlations between AR frequency and polynya opening events, while the four remaining exhibit weakor negative correlations. The highest correlation is observed in Franz Josef Land, which has ahigh amount of both polynya openings and ARs. Furthermore, the regions Kara Sea, Svalbardand Chukchi Sea show a large increase in AR activity over polynya opening locations during theupcoming days of the opening event.These findings suggest that ARs contribute to the triggering or enhancement of polynya openings.Further investigation is needed, as investigating ARs’ effect on polynya openings as opposed toexpansion of already existing polynyas, to better understand the dynamics of Arctic polynyas andAR activity.