卫星观测的我国近海海域闪电分布特征

利用星载闪电探测仪OTD(optical transient detecter)和LIS(lightning imaging sensor)所获取的1995年6月—2006年4月的卫星闪电资料,结合NOAA Optimum Interpolation SST海温资料,分析我国近海海域的闪电分布时空特征以及闪电活动与该海域海温之间的相关性。结果表明:我国近海闪电密度平均值为3.39 fl·km~(-2)·a~(-1),其中,南海和渤海的闪电活动相对频繁,随着与海岸线间距离以及纬度的增加,该海域闪电密度逐渐下降;在春季和冬季,黑潮主干海域的海温值相对较高,该处闪电活动也明显强于同纬度的东海近海和太平洋海域,表明黑潮海域是强闪电活动区;在季节变化上,我国近海海域闪电活动与同海域海温呈明显正相关,相关系数达0.797,闪电活动与海温变化体现出了一致的变化趋势;而在年际变化上,我国近海海域闪电活动与该海域海温的线性相关不显著,说明我国近海海域海温的年际变化并不是引起该海域闪电活动年际变化的主要原因。

Lightning Activities in China Offing Sea Area Observed by Satellite-based Lightning Imaging Sensor

Using observation data of the optical transient detector and the lightning imaging sensor on satellites from April 1995 to April 2006, the spatial and temporal distribution of lightning activities in China offing sea area (including the Bohai Sea, the Yellow Sea, the East China Sea, the South China Sea and some parts of the Pacific in China's terrestrial sea) are statistically examined. The relationship between the lightning activities and the sea temperature is also studied by combing those data with the reanalysis data from the NOAA optimum interpolation SST.The result indicates that the average flash densities in China offing sea area is 3.39 fl·km-2·a-1,which is about 5 times higher than the global ocean average value. The high flash density areas are mostly in the boundary of the land and the sea, especially in the sea areas around the islands, indicating the differ-ence of lightning activity between the sea alongside land and the ocean. The lightning activities in the Bohai Sea and the South China Sea are more frequent than those in the Yellow Sea and the East China Sea.There is a clear tendency that the flash density in China offing sea area decreases gradually with the in-creasing of latitude and the distance off the coast. The flash densities in the sea around the Taiwan Island and the Bohai Sea are the highest. The lightning activity is most frequent in summer, then spring, and in winter it is rare. The sea temperature in the black tide area is higher in winter and spring, and the light-ning activity is more frequent than the East China Sea and parallel ocean sea areas, indicating that the black tide area is a strong lightning activity area.The annual and diurnal change of lightning activities in China offing sea area take on a similar chan-ging trend as that on the land of the same latitude. For the lightning activities of the Bohai Sea and the East China Sea, there's one single peak, while in the South China Sea and the Yellow Sea, lightening ac-tivities take on the similar double peak trends as those in the land of subtropical zone.The lightning activities' annual change is obviously positively correlated to the sea temperature in Chi-na offing sea area. But the flash activity is insensitive to the annual change of the sea temperature, indica-ting that the sea temperature's annual change isn't the main cause for lightning activities' annual change.