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.Various studies have considered the impacts of large-scale factors on heat waves to identify mechanisms generating and developing heat waves. One major factor that causes heat wave events is the presence of large-scale anticyclone circulation over a specific area, producing low cloudiness, clear skies, and warm advection (Black et al., 2004;García-Herrera et al., 2010;Meehl & Tebaldi, 2004). The expansion of the western North Pacific subtropical high (WNPSH) has an important role in influencing summer extreme high temperatures over the East Asia summer monsoon region, including East China, South Korea, and Japan. Xue-zhao and Dao-yi (2002) determined

2018 summer extreme temperatures in South Korea and their intensification under 3 °C global warming

“…The possible mechanisms behind extreme heatwaves in Korea are complex and have not been fully explored (Kim et al 2019). However, the extent and strength of the western North Pacific subtropical high around Korea are often investigated to explain the physical mechanism that is responsible for the heatwaves in South Korea (Yeh et al 2018, Yoon et al 2018. This is because extreme heatwaves are linked to a specific atmospheric circulation at the synoptic scale (Lee and Lee 2016), even though they are a locally dominating phenomenon.…”

Synoptic characteristics of extreme heatwaves over the Korean Peninsula based on ERA Interim reanalysis data

“…For example, Busan experienced an average of 13.2 TNs, which is much greater than 3.4 HW days. These results were consistent with previous research, which indicated that TNs were affected more by urban heat island effect than the air temperature based on city location (Yoon et al ., ). However, the focus of this study is on HW events and TNs were considered only to identify extreme conditions.…”

Study on the Association of Casualties and Classification of Heat Wave Weather Patterns in South Korea Using K-Means Clustering Analysis

“…한반도에 발생하는 폭염에 대한 연구는 주로 사례를 분석 하는 경우가 주를 이루고 있다 (Back et al, 2018;Yoon et al, 2018). 폭염을 유발하는 원인은 발생지역에 따라 다르지만 주로 북태평양 고기압의 발달과 연관성이 높다.…”

“…폭염을 유발하는 원인은 발생지역에 따라 다르지만 주로 북태평양 고기압의 발달과 연관성이 높다. Yoon et al (2018) (Kim and Kim, 2013), 양간지풍은 한반도를 중심으로 기압이 남고북저의 형태로 배치되었을 때 서풍이 태백산맥을 넘으 면서 고온건조한 대기가 영동지역으로 형성된다 (Jang and Chun, 2008;Cho et al, 2015).…”

“…일반적으로 기상학에서는 북태평양 고기압을 분석할 때, 500 hPa 등압면 고도에서 5,880 gpm선을 활용한다 (Choi et al, 2016;J.A. Kim et al, 2016;Back et al, 2018;Yoon et al, 2018 (Fig. 4(a) 날씨유형 2번은 북태평양 고기압(5,880 gpm)이 한반도 중부까지 확장한 것으로 나타났다 (Fig.…”