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

Extreme heat wave sampling and prediction with analog Markov chain and comparisons with deep learning

“…Extreme heat waves, such as the Western European heat wave in 2003 (García-Herrera et al, 2010) and the Russian heat wave in 2010 (Barriopedro et al, 2011;Chen et al, 2022) had consequences on agriculture and posed health hazards. Such events have also affected other regions including Asia, for example, the Korean Peninsula (Choi et al, 2021) in the summers of 2013, 2016(Min et al, 2020. Thus, understanding the potential drivers, forecasting, and performing long-term projections of heat waves is necessary.…”