ISSN 1000-0526
CN 11-2282/P
CN 11-2282/P
Characteristics of Ground Lightning and Relationships of Mesoscale Convective Systems and Heavy Rainfall in a Strong Rainstrom
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Abstract:
Based on the observation data of the lightning location system, temperature of blackbody brightness, Doppler radar echo and denser surface precipitation measurements from the process of a heavy rainstorm during 8-9 August 2007 in the Central Shaanxi Plain, the characteristics of ground lightning，and relationships of ground lightning, MCS, and rainstorm intensity are analyzed separately. The results indicate that the negative ground lightning accounts for the 97.7 percent of the total ground lightning. Hourly evolution tendency of negative ground lightning frequency and total ground lightning frequency presents a two-peak one-valley structure. Positive flash frequency changes have a tri-peak two-valley trend. The ground lightning frequency of 6 min positive and negative flashes in the active negative lightning period displays a trend of multi-peak value. The peaks of positive ground lightning frequency is 12 min prior to negative ground lightning frequency peaks. The relationship of ground lightning and MCS shows that the negative ground lightning happening area is the convective cloud cluster development and strengthening area in the future. The densified locality of negative ground lightning frequency is situated in the concentrated TBB isoline area in front of the convective cloud cluster. The sharp increase of negative ground lightning frequency means MCS development by-and-by. Negative flash occurred mainly in the echo area whose strength is greater than 40 dBz, and positive lightning falls into both sides of strong echo center. During the rapid development of MCS, negative flash dense area is located in the forefront of single echo. In MCS stabilization period, negative flashes are concentrated near the center of the strong echo. The evolution relationship between the ground lightning and the heavy precipitation reveals that the occurrence and sharp growth of the ground lightning have very good indicative significance to the development and strengthening of the rainstorm. The occurrence of the first flash occurs ahead of the strong precipitation happening. The sharp increase of ground lightning has a close connection with the sudden increase of precipitation intensity. And the concentrated regions of the negative ground lightning may indicate the area where strong precipitation happens.
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