Abstract:
Equivalent blackbody temperature (TBB) data from high-resolution satellites were used to identify tracks, and classifies Mesoscale Convective Systems (MCSs) in Sichuan and its surrounding areas (25°N–35°N, 96°E–110°E) during the warm season (May–September) from 2010 to 2022. The analysis focuses on the spatial and temporal distribution, activity characteristics of four MCS types (namely MCC, PECS, M
βCCS, and M
βECS), and their contribution to local precipitation (night/day). The study also examines large-scale circulation conditions that favor MCS formation. The main results are as follows: Circular
β mesoscale convective systems are the most common during the warm season in this region. MCS distribution is dispersed, with active convective areas in the western Sichuan Plateau and the eastern and southern Sichuan Basin, where nighttime convection is notably significant. MCS occurrences peak in July and are the lowest in May, with the strongest convection development in June. α mesoscale circular and
β mesoscale band MCS have larger mean areas, lower minimum cloud top temperature, and longer lifespans at maturity. All four types of MCS show slow development and fast dissipation, with peak generation times between 1700 LST and 1800 LST in the afternoon. MCS-related precipitation accounts for over 25% of total precipitation, with a significantly higher contribution to nighttime precipitation compared to daytime. Favorable conditions for MCS formation and maintenance include the westerly jet and anticyclonic circulation in the upper troposphere, a shallow trough in the middle and lower troposphere, positive relative vorticity zones, cyclonic shear, and water vapor from the Bay of Bengal.