Characteristics of the First Thunderstorm Process in Northwest Hainan Island in 2020

In our report, based on the data of seven regional automatic weather stations in Northwest Hainan Island, the multi-source data of lightning location, weather radar and atmospheric sounding were used to analyze the two earliest thunderstorms（Feb.13-Feb.14） occurred in the northwest of Hainan Island in 2020, and the characteristics of atmospheric environmental parameters related to the studying thunderstorms were also analyzed. The results showed that there are some differences in the activity and echo intensity of the ground flash corresponding to the two thunderstorms: the average frequency of the second thunderstorm and the echo intensity of different stages are greater than that of the first thunderstorm, however, the proportion of positive ground lightning in the first thunderstorm is 46%, and that of the second thunderstorm is only 9%. According to the statistics of daily variation of temperature and humidity in February, it is found that the temperature during thunderstorm activity is higher than that in sunny and rainy days, and the warming trend of afternoon temperature is more obvious; the relative humidity before 14:00 is also higher than that in sunny and rainy days. The radiosonde data showed that the convection available potential energy, the cloud base height and the average relative humidity of the middle layer can be used as indicators of convective activity, among which the mean relative humidity in the middle layer is more reasonable.