Marine Heatwaves in the Arctic Region: Variation in Different Ice Covers

This study analyzes marine heatwaves (MHWs) in the Arctic for its variation in multiyear ice (MYI), first-year ice (FYI), and open-water areas. Results show that there is a significant annual growth in MHW frequency, duration, and intensity in the FYI region, especially for intensity. Since 2005, MHW in FYI increases remarkably in summer and the extent of the affected area continues to grow northward. Particularly, severe MHW events mainly occur in the area where sea ice concentration ranges between 0.1 and 0.5. Stratification in the FYI area impedes the deep mixing and downward transmission of energy from solar radiation, resulting in an anomalously high sea surface temperature in the FYI area. The implication is that MHW will keep growing as the extent of FYI in the Arctic increases. Plain Language Summary The extreme sea surface temperature anomalies events, that is, marine heatwaves, were longer, more frequent, and intense in the Arctic since 2005. Severe events occur mainly in the first-year ice area (sea ice concentration in a range of 0.1 to 0.5) during summer. The affected area continues to extend northward. Ocean stratification in different sea ice covers is found to cause these changes in MHW characteristics.