Regulatory factors and climatic impacts of marine heatwaves over the Arctic Ocean from 1982 to 2020

Abstract

Arctic warming has been substantially greater than that in the rest of the world and has had an important influence on the global climate. This study first explores the temporal and spatial evolutionary characteristics of marine heatwaves (MHWs) over the Arctic Ocean in multiyear ice (MYI), first-year ice (FYI), and open-water (OPW) regions from 1982 to 2020. MHWs in the Arctic Ocean show obvious spatial and seasonal variations, mainly occurring over the FYI region in the JAS (July–August–September, JAS), and their occurrences have a significant increasing trend in recent decades, accompanied by an abrupt increase since 2010. Furthermore, a multivariable network-based method is adopted to delineate the relationship between different climatic factors and MHWs in the Arctic Ocean and the climatic impacts of MHWs. The results show that the correlations between different climatic factors and MHWs in JAS in 2010–2020 are generally stronger than those in 1982–2009, and the main influencing factors of MHWs in different ice covers are different. MHWs in the MYI region are mainly affected by freshwater dilution processes, such as sea-ice concentrations (SIC), precipitation, and mixed-layer salinity. For the FYI region, the 2-m air temperature and total heat flux mainly affect MHWs by thermodynamic processes, and the 500-hPa geopotential height affects MHWs mainly by large-scale atmospheric circulation. The MHWs in the OPW region are mainly related to the SIC, 850-hPa geopotential height, and 10-m v-wind, indicating that they are correlated with atmospheric processes and wind fields. MHWs in JAS are also revealed to reduce or delay the formation of sea ice in OND (October–November–December, OND) by storing more abnormal heat, indicating that unfrozen ocean surfaces may lead to enhanced Arctic amplification in the following seasons.