| This articles uses the 2017 WWLLN lightning detection data,the ground flash data of the lightning positioning system of the meteorological department of Qinghai Province in 2013-2017,and the eastern part of the Qinghai-Tibet Plateau acquired by the Doppler weather radar in Xining City in the summer of 2013-2017(June-August)Radar data are used to analyze the distribution characteristics of lightning in different regions of China and the characteristics of thunderstorms and ground flashes in the eastern part of the Qinghai-Tibet Plateau.The results show:(1)China's land-based lightning is mainly concentrated in the southern region,and the lightning density high-value area is located in Guangdong Province and southern Guangxi Province.The main active period of lightning is from June to September.Different provinces have different lightning active periods and shorten with the increase of latitude.The close distance from the sea is an important factor affecting the distribution of lightning in the Guangdong region at low latitudes.In Yunnan,Sichuan and Tibet,where the terrain is different and the climate is complex and diverse,the distribution of lightning in summer is mainly affected by the climate,while in autumn,it is mainly affected by the terrain.Heilongjiang Province and Shandong Province belong to the temperate continental climate,and Heilongjiang Province with higher altitude also has more lightning frequency.There is a positive correlation between the CAPE value in the same area and the number of lightning occurrences,and the CAPE value is larger in places where lightning occurs.(2)Based on the cloud-to-ground(CG)lightning data in the National Lightning Monitoring and positioning system and radar data,this paper made a comprehensive analysis of the typical strong thunderstorm in the eastern Tibet Plateau in the summer of 2013-2017(June-August).24 cases of thunderstorm with mainly negative lightning were analyzed in this article,the results show that the maximum radar echo top of all24 thunderstorms reached or exceeded 7 km.Thunderstorm whose first CG lightning is positive CG lightning has greater composite reflectivity and radar echo top than whose first CG lightning is negative.In this paper,thunderstorms are divided into three types: negative CG lightning thunderstorm,positive CG lightning thunderstorms and multiple CG lightning thunderstorm.The number of lightning and the period when lightning occurs in the three types of thunderstorms are different.The number of lightning that occurred during negative CG lightning thunderstorms is less,mostlyoccurred during the mature period;The number of lightning that occurred during positive CG lightning thunderstorms is about dozens of times,mostly occurred during the mature period and dissipation period;For multiple CG lightning thunderstorms,lightning occurred in the development,maturation and dissipation periods,but mainly in the maturation and dissipation periods.The moving distances and moving speeds of strong reflectance center for three types of thunderstorms are also different.A thunderstorm with a large number of lightnings has a longer moving distance than a thunderstorm with a small number of lightnings,and negative CG lightning thunderstorm has a faster moving speed than positive CG lightning thunderstorm.(3)There is a positive correlation between the area of the strong echo region and the frequency of lightning.The change of the top height of the echo is consistent with the change of the frequency of the CG lightning,but the former is obviously ahead of the latter.The vertical accumulated liquid water content is large in the initial stage and the frequent of CG lightning,and the occurrence position of ground flash coincides with the area with large liquid water content.There will be no data area(ND area)on the vertical wind profile of the thunderstorm cloud before the lightning occurs and the lightning frequency increases.The ND area begins to recover after the lightning disappears for about 40 minutes. |
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