Potential Precursory Signals of Localized Torrential Rainfall From Geostationary Satellite and Radar Observations: A Case Study of the 2022 Seoul Flood

Abstract

The Korean Peninsula frequently experiences localized torrential rainfall (LTR) in the summer. However, on August 8, 2022, a peculiar LTR occurred by the continuous generation of convective clouds within a few hours, numerical weather prediction model was hard to forecast such a high intensity of LTR. This study explores the possibility of uncovering potential precursory signals using remote sensing techniques in both Geostationary Korea Multi-Purpose Satellite 2A (GK2A) and the operational RKSG (Camp Humphreys) Weather Surveillance Radar 88 Doppler (WSR-88D). Using cloud properties from GK2A, cloud top temperature showed a decrease and maintained low values below 220 K 1–1.5 h before the LTR events. However, discerning the exact onset of LTR in already mature stage clouds using only GK2A variables proved challenging. Instead, liquid water content from RKSG sharply increased before the LTR started. Our calculation of the LTR potential from a combination of GK2A and RKSG cloud properties shows a more accurate precursory signal of LTR than from GK2A cloud properties solely or RKSG either. This study highlights the synergistic benefits of combining geostationary satellite and radar observations to understand and predict early precursors of LTR events.