Articles | Volume 16, issue 4
Research article
12 Apr 2016
Research article |  | 12 Apr 2016

Characteristics of mesoscale-convective-system-produced extreme rainfall over southeastern South Korea: 7 July 2009

Jong-Hoon Jeong, Dong-In Lee, Chung-Chieh Wang, and In-Seong Han

Abstract. An extreme-rainfall-producing mesoscale convective system (MCS) associated with the Changma front in southeastern South Korea was investigated using observational data. This event recorded historic rainfall and led to devastating flash floods and landslides in the Busan metropolitan area on 7 July 2009. The aim of the present study is to analyse the influences for the synoptic and mesoscale environment, and the reasons that the quasi-stationary MCS causes extreme rainfall. Synoptic and mesoscale analyses indicate that the MCS and heavy rainfall occurred in association with a stationary front which resembled a warm front in structure. A strong southwesterly low-level jet (LLJ) transported warm and humid air and supplied the moisture toward the front, and the air rose upwards above the frontal surface. As the moist air was conditionally unstable, repeated upstream initiation of deep convection by back-building occurred at the coastline, while old cells moved downstream parallel to the convective line with training effect. Because the motion of convective cells nearly opposed the backward propagation, the system as a whole moved slowly. The back-building behaviour was linked to the convectively generated cold pool and its outflow boundary, which played a role in the propagation and maintenance of the rainfall system. As a result, the quasi-stationary MCS caused a prolonged duration of heavy rainfall, leading to extreme rainfall over the Busan metropolitan area.

Short summary
An extreme rainfall-producing mesoscale convective system (MCS) associated with the Changma front in south-eastern South Korea was investigated using observational data. The aim of the present study is to analyze and better understand the synoptic and mesoscale environment and the behaviour of the MCS causing natural hazards over South Korea.
Final-revised paper