Impacts of Synoptic and Local Factors on Heat Wave Events Over Southeastern Region of Korea in 2015

Abstract

Because of global warming and abnormal climate change, record‐breaking heat wave events have been increasing. Therefore, it is necessary to analyze and predict the mechanisms for generating and developing heat waves. In this study, the impacts of synoptic and local factors on heat waves over the southeastern region of South Korea in 2015 are investigated. First, Heat wave events for 1980-2016 defined by spatiotemporal criteria are classified into three clusters using the K‐means clustering analysis. Heat wave events in 2015 are compared to clusters of different synoptic conditions, which are strongly related to the western North Pacific subtropical high around South Korea. Second, numerical experiments using Weather Research and Forecasting model are performed to examine the effect of local conditions on 2015 heat waves. Four types of sensitivity experiments were conducted: a CTL experiment with no change in topography and soil moisture, TOPO experiment with lowered terrain, and WET and DRY experiments with wet and dry anomalies in initial soil moisture. The CTL experiment simulates higher temperature on the lee side compared to the TOPO experiment because of the Foehn effect. In particular, the effect is prominent when dry westerlies passing through mountains and the lower level atmosphere over the windward region are in a statically stable condition (i.e., nighttime). Due to the less (more) evaporation, the DRY (WET) experiment with less (more) soil moisture simulates higher (lower) maximum temperature than the CTL experiment during the daytime when solar radiation is relatively intense.