Investigating the Influence of Water Vapor on Heavy Rainfall Events in the Southern Korean Peninsula

Abstract

In this study, we examined the influence of water vapor on heavy rainfall events over the complex mountainous terrain of the southern Korean Peninsula using rawinsonde and global navigation satellite system (GNSS) datasets from a mobile observation vehicle (MOVE). Results demonstrated that the prevailing southeasterly winds enhanced precipitation on the leeward side of the mountainous region. The probability of severe rainfall increased in the highest precipitable water vapor (PWV) bin (>60 mm). A lead–lag analysis demonstrated that the atmosphere remained moist for 1 h before and after heavy rainfall. The temporal behavior of PWV retrieved from the MOVE-GNSS data demonstrated that during Changma (the summer monsoon) (Case 1), heavy rainfall events experience a steep decrease after a long increasing trend in PWV. However, the most intense rainfall events occurred after a rapid increase in PWV along with a strong southwesterly water vapor flow during convective instability (Case 2), and they had consistently higher moisture and greater instability than those in Case 1 over the entire period. The results of this study can provide some insights to improve the predictability of heavy rainfall in the southern Korean Peninsula.