Comparative Analysis of Characteristics of Mesoscale Convective Systems in Observations and Model Simulation

Mesoscale convective systems (MCSs) accompany severe weather phenomena, which result in significant damage in human lives and infrastructure, such as heavy rain, strong winds and hail. Unfortunately, the forecasting accuracy of MCSs often falls due to the lack of understanding of dynamic and thermodynamic processes in developing and dissipating them. Therefore, it is necessary to figure out the mechanism of MCSs to improve forecast accuracy. Considering geographical conditions, MCSs in South Korea develop in the moist rich environment and interact closely with the heterogeneous surface due to the complex topography. To understand mechanisms in the distinct environment, we investigate characteristics of MCSs, which occurred in South Korea for 2018-2021, in observations and model simulation.
The procedures for characterizing MCSs based on comparative analysis were divided into three steps: 1) classification of the MCS types, 2) determination of reference time and location, 3) composite analysis. MCSs were classified into four classes according to the morphological and movement features of them based on the visual inspection, namely, convective cells (CC), mesoscale convective complex (MCC), and parallel/diagonal squall line (PSL/DSL). The reference time and location for composite analysis were determined using the largest 12 h accumulated rainfall from AWS (Automatic Weather Station) reanalysis data. Then, we analyzed the dynamical and thermodynamical variables derived from observation data and European Centre for Medium-Range Weather Forecasts (ECMWF) fifth-generation reanalysis data (ERA5) through composite analysis. The composite analysis was performed according to MCSs type to examine the characteristics of each MCSs types. In conclusion, we generalize and analyze the environmental conditions and mechanisms which are favorable for development and dissipation of each MCSs type based on composite analysis.