Characteristics of Rawinsonde Data-Based Storm-Relative Helicity Collected during the Early Summer Monsoon Period in the Southwest Korean Peninsula

Abstract

The kinetic energy associated with Chang-ma periods was investigated using rawinsonde data from Korea during 2013−2015. Changes in kinetic energy (which is defined in terms of storm relative helicity, SRH) were more pronounced than changes in thermal energy (which is defined in terms of convective available potential energy, CAPE) during precipitation. The median value of SRH increased by 14, 125, and 185 m 2 s −2 in no-rain, weakrain (< 5 mm 3 hr −1), and strong-rain (≥ 5 mm 3 hr −1) time periods, respectively. However, the values of CAPE remained below 100 J kg −1 regardless of the rainfall intensity. Moreover, the correlation coefficients (R) between SRH and precipitation amount about 0.4 with 99% confidence level. In addition, we used two vectors constituting the SRH (storm motion vector and horizontal wind vector) to determine the reason for the SRH differences. The change in the y-components of the horizontal wind vector at low levels (850−750 hPa) was determined to be closely related to SRH. The increase in SRH during the precipitation periods was therefore determined to be due to the low-level southerly wind. Based on these results, we conclude that SRH can be used not only to predict mesoscale storms but also to forecast precipitation in the early summer monsoon season in Korea.

Environment and Processes for Heavy Rainfall in the Early Morning over the Korean Peninsula during Episodes of Cloud Clusters Associated with Mesoscale Troughs

“…As a meso-α-scale depression moves or develops along the northwestern edge of the WPSH, southwesterlies to the southeast of the depression become stronger (Shin and Lee 2015). Various studies have also found the importance of strong southwesterlies or low-level jets (LLJs) for heavy rainfall over the Korean peninsula (e.g., Kim et al 1983;Hwang and Lee 1993;Chen, S. et al 1999;Jung et al 2018).…”