Synoptic conditions controlling the seasonal onset and days of heatwaves over Korea

Abstract As global warming gets worse, the extreme heat exposure time is expected to increase. Considering that heatwave damages increased by accumulation of stress, it important understand onset and number days (HWDs). Here, we show end East Asian summer monsoon activity (i.e., Changma retreat date, CRD) could be an indicator in determining heatwave, barotropic structure induced circumglobal Pacific–Japan teleconnections a key factor lengthening HWDs Korea. The delayed when CRD belated than climatology late over Korea due sufficient moisture transportation between edge western North Pacific subtropical high cold polar air mass July. from July through August shows positive linear relationship with synoptic stagnation index because upper-layer anticyclone associated formed around zonal wave activity. Barotropic stabilizes atmosphere increases clear sky days, which possibly leads hot days. Fewer are observed there baroclinic instability strong upper-level jet stream synoptic-scale weather systems move smoothly. By identifying meteorological mechanism occurrence favorable conditions for sustained Korea, our results eventually able contribute reducing caused heatwaves.