Analysis of Multi-time Scale Variation Characteristics and Climate Regulation Factors on Global Marine Heatwaves

Based on National Oceanic and Atmospheric Administration (NOAA) Daily Optimum Interpolation Sea Surface Temperature V2 (OISST) observation data and various Physical Sciences Laboratory climate observation indexes from 1982 to 2019, statistical methods such as least square regression, high-low pass filtering, and correlation analysis were adopted to analyze the multi-timescale evolution characteristics of the global Marine Heatwaves (MHWs) frequency, duration, total days, and maximum intensity and the regulation effect of different climate signals on its evolution. Research shows that the MHW frequency linearly grows the fastest in the equatorial western Pacific. After removing the global warming trend, the interannual and interdecadal changes in the global mean MHWs have obvious regional variation characteristics, and all the dominant regions are modulated by the climate signals of multiple timescales. This study analyzes the correlation between the MHW properties and different climate signals in five key sea areas (equatorial central and eastern Pacific Ocean, northeast Pacific Ocean, western Indian Ocean, northwest Atlantic Ocean, and mid-high latitude Southern Ocean). Results show that the frequency of the MHWs in the five key sea areas is mainly modulated by interannual climate signals. The interdecadal climate signal mainly provides a background state, and its influence on the frequency evolution of MHWs in the key areas is not as significant as that of the interannual climate signal.