Variations on the Meso- and Micro-scale Structures of Mesoscale Convective Systems Under Different Large-scale Circulations over Southern China

Mesoscale convective systems (MCSs) frequently occur and cause severe weathers in Southern China (SCH). The SCH MCSs could be attributed to a variety of synoptic patterns, such as cold front, low-level shear line, subtropical (southwest) vortex, mid-level trough, tropical cyclone (TC), tropical vortex (non-TC), and weak synoptics. Though the synoptic systems are well understood, what are their contribution to the total MCS activity and how they influence MCSs’ meso- and micro-scale structures are less known. This study first identifies and tracks the lifecycles of more than 800 MCSs over SCH using the operational radar network data in China. Observations from radar, satellite, rain gauge, and lightning network, are then collocated into MCSs to quantify their rain intensity, horizontal organization, convective intensity, vertical precipitation structure, and ensemble microphysics. Results show significant difference on the MCS structures among the above-mentioned large-scale patterns. For example, subtropical-vortex MCSs are the most long-lived, the largest in size and the strongest in convective intensity. Though MCSs induced by TCs and tropical vortex produce the heavier rainfall, they have the weakest convective intensity and the least lightning activity. Also, these MCSs have a very deep column of total ice particles but much less large-size ice particles than the subtropical-vortex MCSs. Mechanisms responsible for the changes on the MCSs’ meso- and micro-scale structures among different synoptic conditions are further investigated.