Study on lightning activity and precipitation characteristics before and after the onset of the South China Sea summer monsoon

Abstract

The data from the lightning imaging sensor (LIS), precipitation radar (PR), and passive microwave imaging (TMI) onboard the Tropical Rainfall Measuring Mission (TRMM) satellite from 1998 to 2005 have been used to investigate the lightning activity and precipitation characteristics before and after the onset of the South China Sea (SCS) summer monsoon. The results show that the lightning activity over the SCS begin to enhance in April, peak in May, and decrease after June. Compared to the premonsoon season, mean cell‐level flash rate decreased 13% and mean flash optical radiance increased 15% during the monsoon season, respectively. The mean flash rate is higher during the premonsoon season. On the basis of the observations of PR and TMI, it can be found that vertical development of precipitation systems in the premonsoon season was stronger than that in the monsoon season, so frequent lightning activity were observed. Further research indicates that when maximum radar reflectivity at 7 km asl reached 36 dBZ, the probability of lightning occurrence was 50% in the premonsoon season, and it increased to 38 dBZ in the monsoon season. The flash rate of precipitation systems can be expressed as functions of maximum storm top height, maximum snow depth and minimum polarization corrected temperatures (PCTs), respectively. Among those, the most stable one is the relationship between flash rate and maximum snow depth.