Spatiotemporal patterns of marine heatwaves in the Southern Ocean and their role in air-sea interaction

Marine heatwaves (MHWs) are extended periods of abnormally warm ocean conditions in which temperature exceeds the 90th percentile threshold limit. While prior studies have mainly focused on regional trends, the Southern Ocean, particularly around Antarctica, has been relatively understudied despite experiencing considerable warming in recent decades. This study investigates MHWs in the Southern Ocean from 1982 to 2022, highlighting significant spatial and temporal variations in their frequency, intensity, and days. MHWs were found to be more frequent (0.4 events per decade) and intense north of 65°S, especially during the summer, with a marked rise in occurrence after 2008, coinciding with anthropogenic climate change and increasing sea surface temperatures (SST). The study also identifies the influence of climate patterns such as El Niño and the Indian Ocean Dipole (IOD) on MHWs intensity and frequency, particularly in the Ross Sea during spring and autumn. We analyzed the atmospheric impacts of significant MHWs in 2013. The 2013 MHW event serves as a key example of extreme subsurface warming, where temperatures reached 6.2 °C at 120 m depth, significantly increasing the region's heat content. This highlights how MHWs can transmit heat vertically, impacting both surface and deep ocean layers. The findings emphasize the complex interactions between ocean dynamics, and atmospheric conditions in determining MHWs patterns in the Southern Ocean, offering crucial insights for predicting the region's future responses to climate change.