资源环境科技发展态势分析平台

This study analyzes general features and circulation patterns of 98 quasi-linear meso-scale convective systems (MCSs) over South China (SC) during May 1 to June 15, 2013–2017 using high resolution gridded radar network dataset and the obliquely rotated principal component analysis in T mode. The MCSs prefer to form over northwest SC (N-GX) around midnight, and over southwest SC (S-GX) and Pearl River Delta (PRD) in east SC in the morning. After formation, the MCSs over N-GX, S-GX, and PRD are prone to move southeasterly, northeasterly, and easterly, respectively. Five organization modes of MCSs are identified at their mature stages: a convective line with trailing stratiform precipitation (TS), without stratiform precipitation (NS), embedded in stratiform precipitation (EL) or with parallel stratiform precipitation (PS), and multiple convective lines with stratiform precipitation (MLS). The MLS mode mainly presents near the coastline with the longest lifespan (about 6.6 h) and lowest moving speed (about 14.0 km h⁻¹), while the TS mode widely spreads over SC with the fastest moving speed (about 44.6 km h⁻¹) and the second-longest lifespan (about 5.4 h). Transition of the modes during the MCSs' lifetime is revealed. The circulation patterns in the lower troposphere around SC during the analysis period are classified into six types. The MCSs mostly (about 80%) occur in three types featured with stronger low-level southwesterly winds compared with the other three patterns. With the three favorable patterns, positive anomalies of convective available potential energy and surface-to-700 hPa vertical wind shear are observed on the days with MCSs. The circulation patterns are also closely associated with the different movement of MCSs formed in N-GX, S-GX and PRD.