Distinct mechanisms of Korean surface temperature variability during early and late summer

Abstract

Several climate factors were identified that affect the surface air temperature (SAT) variations in Korea during summer (June‐July‐August). Korean summer SAT variation exhibits remarkable differences between early summer (June) and late summer (July and August). On one hand, the significant warming trend during early summer is primarily influenced by the global‐scale trend that is manifested in East Asia. The residual variability, obtained by removing warming trend from total SAT, represents Korean SAT variability independent of the global‐scale trend. This residual variability is closely related to the meridional dipole‐like air temperature structure between Korea and northeastern China, which is largely controlled by the atmospheric circulations over East Asia. However, this atmospheric structure does not originate from the remote oceanic forcing such as sea surface temperature (SST) variability over Pacific. During late summer, on the other hand, the Korean SAT is dominantly regulated by the atmospheric variability, which is closely related to the Pacific SST variability, while the contribution of global warming signal is insignificant. The SST anomalies in the central to eastern tropical Pacific lead to a dipole‐like atmospheric circulation from the tropics to East Asia, which modulates SAT in Korea. These results imply that the Korean SAT variability during early and late summer has different sources. That is, both the global‐scale trend and atmospheric variability over the East Asia should be considered in monitoring Korean SAT during early summer, whereas the SST variability in the central to eastern tropical Pacific needs more attention during late summer.

Two Types of Heat Wave in Korea Associated With Atmospheric Circulation Pattern

“…Lee and Lee () also obtained the La Niña‐ like pattern in association with the interannual variation of heat wave frequency in Korea. Also, this result is consistent with previous studies that summer air temperature in Korea, Japan, and northeastern China becomes generally warmer than normal during La Niña years (Ueda et al, ; Wang et al, ; Wu et al, ; Yeo et al, ). In general, the negative SST anomalies over the tropical eastern Pacific are able to enhance the convective activities over the tropical western Pacific via Gill type response (Gill, ), which is the Rossby wave response to the anomalous diabatic heating in tropics.…”

“…We further investigate the thermodynamical characteristics of the two types of heat wave. The time rate of the local temperature change can be explained by the heating rate from net surface heat flux and thermal advection (e.g., Kim et al, ; Wang et al, ; Yeo et al, ). The net surface heat flux over Korea shows typical features of heat wave with upward sensible heat flux and downward latent heat flux for both type of heat wave (Figure S2).…”

Probabilistic Heat Wave Forecast Based on a Large-Scale Circulation Pattern Using the TIGGE Data

“…The South Korea surface air temperature in June is associated with land-sea thermal contrast around East Asia. On the other hand, the enhanced convective activity over western tropical Pacific is an important factor the affects the South Korea surface air temperature in July and August (Yeo et al 2017).…”

Diagnosing Physical Mechanisms Leading to Pure Heat Waves Versus Pure Tropical Nights Over the Korean Peninsula

“…In particular, most previous studies have focused on analyzing the surface temperature variability averaged over the entire summer season, that is, June‐July‐August. However, the Korean summer displays pronounced subseasonal variability of surface temperature and precipitation (Wang et al, ; Yeo et al, , ). For example, the period from the mid‐June to the mid‐July corresponds to the Korean rainy season.…”