Graphical Abstract

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Li, Z., Y. Luo, Y. Du, and J. C. L. Chan, 2020: Statistical characteristics of pre-summer rainfall over South China and associated synoptic conditions. J. Meteor. Soc. Japan, 98, 213-233.
https://doi.org/10.2151/jmsj.2020-012
Graphical Abstract

Plain Language Summary: After the South China Sea (SCS) monsoon onset, an increase in domain-averaged rainfall accumulation and a generally enhanced convective intensity over South China (SC) during Apr-Jun were previously noticed. This study comparatively examines the characteristics of rainfall over the west-inland, east-inland, and coastal regions of SC during pre- and post-monsoon onset periods, and discuss the associated synoptic conditions and physical mechanisms.

Highlights:

• After the monsoon onset, accumulated rainfall amounts increase over the west-inland and coastal regions, whereas remain nearly unchanged in the east-inland region due to its enhanced intensity but fewer occurrences of rainfall.
• Favorable dynamic instability and thermodynamic conditions for the inland rainfall result from collective effects of a subtropical low pressure/front/shearline and southwesterly air flow of tropical origin.
• The deceleration of the southerly BL flow over the northern SCS leads to convergence of BL high-θ_e air near the coast, which is a key factor in producing the coastal, warm-sector rainfall. However, heavy rainfall could occur near the coast even the southerly air flows in the BL and lower troposphere are too weak to be considered as jets.