Interannual variability in the sea surface cooling induced by tropical cyclones in the South China Sea

Sea surface cooling induced by tropical cyclones(TCs)is an important component of air-sea interactions.Using coordinate transformation and composite analysis methods,we examined the interannual variability in TCinduced sea surface cooling(TCSSC)in the South China Sea(SCS).The frequency of surface cooling cases was over 86%and that of surface warming cases was less than 14%.The magnitude of TCSSC was defined as the absolute value of TCSSC.The maximum magnitude of TCSSC occurred on the right side of the TC track,and the mean magnitude of TCSSC decreased by 0.04℃/a from 2006 to 2018.The interannual variability in TCSSC was highly correlated with the TC translation speed and pre-TC mixed layer depth.Notably,TCSSC got enhanced in El Nino years of 2007,2010,and 2015.The El Nino types were suggested to determine the occurring periods of strong TCSSC via controlling the positions of SCS anticyclones,which brought pre-TC shallow mixed layer and caused strong TCSSC via vertical mixing process during El Nino events.To quantify how the anticyclone influences TCSSC,we need to use mixed layer heat balances model in the next study.