Analysis Of Severe Convection Weather In Southeast Coast And Research Of The Lightning Nowcasting

The lightning activities in China are mainly distributed in the southeast coastal areas such as Guangdong Province and Hainan Province. The humid environment, low latitude location and special terrain conditions provide sufficient conditions for the development of strong convection. This paper takes Guangdong Province as an example, discusses the characteristics of lightning activities in the area, and analyzes the Lightning Nowcasting and warning. Firstly, this paper analysis lightning activity based on the lightning location data, LIS and WWLLN data of Guangdong Province. Using these dates, we study the relationship between lightning frequency and radar echo in a strong squall line. Secondly, This paper selected the typhoons landing in Guangdong from 2008 to 2013 to analyze the spatial and temporal distribution and their variation characteristics of typhoon lightning, especially for the statistical study on the characteristics and differences of lightning activity before and after the landfall of the typhoons, we do a detailed analysis of the landfall process of typhoon "Doksuri" which caused severe disaster makes a statistical analysis of the typhoon in Guangdong province. Finally, this paper uses Thunderstorm, Identification, Tracking, Analysis and Nowcasting (TITAN) algorithm to identify cells with reflectivity>40 dBZ and the lightning location data, and contrast the differences between the two results. The main results are as follows:(1)The lightning location system detect ground flash density reached 9fl·km-2·al, LIS detecting of cloud flash and flash information in Guangdong. Lightning density reached 35 fl·km-2·a-1.Lightning density detected by WWLLN is smaller than LIS. Using the lightning location data, radar data of Shenzhen to analyze a squall line process, We find that flash are mainly distributed in the area with strong echo (echo intensity>40dBZ), few occurred in the edge of the squall line system and weak echo region. However, from the whole process, the ground flashing zone distribution and radar strong echo showed a good corresponding relationship.(2) The number of typhoons landed in Guangdong is decreasing, but the number of strong typhoon and super typhoon is increasing year by year from 2008 to 2013. Typhoon lightning is the most active at a distance of 340-360 km to the center after the typhoon landed. Taking " Doksuri" as an example, During stage of development, convective system developed quickly, and lightning occurred in low TBB value area which is outside the 300 km from the center, especially the scope of TBB is less than 210K. In the mature stage, the regional center began to appear a small amount of lightning, lightning occurs in most of the TBB ranged from 220 K to 230 K in the region. Lightning occurred in the average with relative humidity between 60%to 80%.But less lightning occurred in the relative humidity more than 90%.(3) TITAN algorithm can identify the strong radar echo area and lightning high-density areas, but there are differences in the identification result. The accuracy of nowcasting is related to the start time and the length of nowcasting time. The forecasting effect is more ideal using lightning data than radar echo.