Satellites reveal different stories of marine heatwaves in the sea-ice-covered pan-Arctic

Satellite observations provide valuable information on the rapidly increasing marine heatwaves over the Arctic Ocean, yet current assessments of these events lack reliability because the satellite-based temperature in ice-covered regions heavily relies on ice conditions. Here we compared the marine heatwaves derived from two commonly used satellite products to evaluate the potential influences of sea ice in the pan-Arctic. We found inconsistent behaviors of marine heatwaves in both mean fields and temporal variations on interannual and seasonal timescales using two datasets, which became even larger in recent years when they showed opposite tendencies over regions with higher ice concentrations (>50%). Our findings revealed our knowledge of marine heatwaves in the Arctic is facing challenges due to the large influences of sea ice and datasets that were ignored in previous studies, highlighting an urgent need for in situ observations and consistent and reliable long-time datasets for the warming Arctic.