Identifying Dynamic and Thermodynamic Contributions to the Record-Breaking 2022 Summer Extreme Rainfall Events in Korea

Abstract

In 2022, South Korea experienced a series of climate extremes, among which the August 8 extreme rainfall event stands out due to its considerable damage to Seoul, with daily precipitation exceeding 380 mm/d. This study aimed to examine the contributions of dynamic and thermodynamic components in the moisture budget to two major extreme rainfall events occurring on June 27-30 and August 8-11 in 2022. Our analysis revealed the distinctive roles of wind and moisture content during these extreme rainfall events. In both events, the changes in the wind (dynamic components) played a crucial role, mainly attributed to the northward or westward shift of the subtropical high. On the other hand, the moisture content (thermodynamic component) contributed to approximately 30% of the rainfall but only for the period from August 8 to 11. The subtropical thermal forcings, positive North Atlantic Oscillation, and the intensified rainfall in Pakistan induced circulation changes that redistributed the thermodynamic characteristics. Consequently, substantial meridional pressure gradients developed, giving rise to zonally elongated rainfall patterns that appeared to be characteristics of both extreme rainfall events. These findings shed light on the factors that influenced extreme rainfall events in South Korea in 2022 and highlight the crucial role of remote forcing in predicting such events.