Analysis of MCS activity characteristics during extreme heavy rainfall in the Yangtze River Basin from July 4 to 10, 2020

Abstract

During July 4 to 10, an extreme heavy rainfall occurred in the Yangtze River Basin. By using high temporal and spatial resolution FY-4A blackbody temperature (TBB) data and the China hourly merged precipitation analysis combining observations from automatic weather stations with CMORPH products, an automatic identification and tracking method of convection is applied to analyze the identification, tracking and classification of the mesoscale convective system (MCS) in the secondary terrain and the east region (105°-125°E, 25°-35°N) in Yangtze river basin. The western, eastern and east-moving types of MCS are classified, and their spatial and temporal distribution characteristics and the physical parameters are studied. Results showed that the number of MCS generated in the western region increased significantly, remain unchanged in the eastern region, and occurred mostly in the east-moving type in July 5 to 6. The initiation peak of western and eastern types generally occurs in the afternoon and early morning, while the east-moving type mainly occurs in the early morning. The east-moving type is more easterly than that of the western type MCS, which is more favorable for east moving to affect the downstream area. Compared with western and eastern type MCS, lower TBB, greater rainfall intensity, longer life duration, more rapidly development, larger rainfall area and convective cloud area, longer moving path and wider influence range are presented in east-moving MCS, indicating that the east-moving MCS is more vigorous. Meanwhile, with the increase of life duration, the number of MαCS increases, while the number of MβCS decreases gradually.

Keywords

• yangtze river basin
• mesoscale convective system
• temporal and spatial distribution
• physical parameter characteristics