Lightning Activities on Qinghai-Xizang Plateau as Observed by Satellite-Based Lightning Imaging Sensor
Qie Xiu · Gaoyuan qixiang · 2003
The lightning flash activities on Qinghai\|Xizang Plateau are being studied, for the first time, by using Lightning Imaging Sensor (LIS) database. The flash activity is found to exhibit a continental type climate behavior and is a sensitive indicator of solar heating on the Plateau. Over 93% of the flashes are found to occur during May to September with a single peak in the summer. The monthly variation clearly shows a flash activity in May with the increase of surface heating and moisture. The high flash density on the Central Plateau reveals the affinity of lightning activity with the topography. The diurnal variation of the flash activity shows a peak activity from 14:00 to 18:00 LT with 63% of all flash activities occuring in this period. Less than 3% of all lightning flashes are observed between 00:00～10:00 LT. There is also a diurnal variation in the meanflash radiance with a sharp drop at around 02:00 LT, and increases rapidly from 08:00 LTwith the sunrise. The optical radiance of flashes onthe Plateau can be fitted well to a lognormal distribution with energetic flashes on the Northern Plateau and weak flashes on the Western Plateau. The lower flash discharge energy on Qinghai\|Xizang Plateau could be attibuted to the lower convective available potential energy and the lower cloud top.