Thunderstorm Structure and Lightning Property over South China and the South China Sea: A Comparative Study

Using lightning data from the Lightning Imaging Sensor (LIS) aboard the Tropical Rainfall Measurement Mission (TRMM) satellite and cloud and precipitation property data from the Radar Precipitation Feature (RPF) during 1998–2014, this study investigates the statistical characteristics of thunderstorm structures and lightning properties over the land (South China) and the South China Sea (SCS), aiming to compare the thunderstorm structural differences and explore the impact of thunderstorm structures on lightning properties between land and transition water areas to deep ocean. The results show that lightning activity in South China is significantly more intense than that in the SCS, with an average lightning frequency and density about twice as high as that of the latter. However, the mean flash duration is similar in the two regions, and lightning in the SCS exhibits larger averages for flash length, footprint, and radiance. In addition, the horizontal scale and vertical extension of thunderstorms in the SCS are significantly larger than those in South China, with twice the sizes of the thunderstorm precipitation area and the 20-dBZ area, and 1.25 km higher for average top height of the 20-dBZ echo. Nevertheless, thunderstorms in South China develop more intensely, with elevated heights of intense convective core (40-dBZ echo top) compared to those in the SCS. The mean values of 37-GHz minimum polarization-corrected temperature (PCT) are comparable in the two regions, but the 85-GHz PCT mean value is lower in the SCS, suggesting a higher concentration of small ice particles in the SCS thunderstorms. Finally, a conceptual diagram that highlights the differences in thunderstorm structures and lightning flash properties between South China and the SCS is proposed. Compared to previous studies, this study indicates the distinct characteristics of oceanic lightning in the SCS and highlights the gradual transition of thunderstorm scale and lightning properties from land then to the SCS finally to the deep ocean over the Northwest Pacific.