ANALYSIS OF LIGHTNING ACTIVITY OVER THE YANGTZE RIVER DELTA USING TRMM/LIS OBSERVATIONS

In terms of TRMM/Lightning Imaging Sensor (LIS) data, the lightning activity over the Yangtze River Delta from 1998 to 2004 is undertaken. After applying the observation efficiency correction for the LIS data and using the viewing times statistics of LIS over the target area, the temporal (annual and diurnal) and spatial distributions of LIS lightning are depicted. The number of lightning flashes observed by LIS varies year by year, and the maximum is about three times the minimum. About 60% of the lightning days and 70% of the lightning flashes of a year occurs during July and August, with lightning peaking in the afternoon. The lightning activity peaks in the early evening in other months. In Shanghai, severe thunderstorms often occurs when the number of LIS lightning flashes in a day is more than eight. Fewer lighting flashes and days are found over water areas. Some lightning activity centers are found downstream of metropolis such as the east part of Shanghai, and mountain areas such as Longmen Mountains. When moving off shore, some thunderstorms tend to intensify and produce more flashes. Results show that the temporal change in solar radiation brings about the temporal distribution of LIS lightning activity. The physical features of surface and topography may be major causes for the difference in the spatial distribution of lightning in mesoscale. Comparisons with ground-based observations, such as Doppler weather radar and the SAFIR total lighting localization system are also made。