香港地区地闪时空分布特征及其影响因素

通过对香港地区2006—2012年闪电定位数据、气象参数和海拔高度等相关数据的统计及相关性分析，对香港地区的地闪活动时空分布特征及其影响因素进行研究。结果表明，香港地区2006—2012年的地闪发生次数最多的是2010年，最少是2011年，每年地闪高发日的天数对地闪活动年际变化起到了关键性作用。地闪活动的发生主要集中在4—9月，逐月地闪回击次数与气温、相对湿度、降雨量及CAPE均呈现显著的正相关关系。地闪活动的日变化特征主要受到地闪高发日闪电活动、海陆热力差异及太阳辐射变化的综合影响，正、负地闪回击次数的日变化峰值均出现在01时。香港西部地区的正地闪回击密度明显高于东部，而负地闪回击密度的高值中心主要集中在海拔较高的山区。香港地区正、负地闪回击密度均随海拔的升高而有所增加，且六座典型山峰周围的负地闪回击密度与海拔高度在空间分布特征上具有很强的相似性。 

TEMPORAL AND SPATIAL DISTRIBUTION CHARACTERISTICS OF CLOUD-TO-GROUND LIGHTNING ACTIVITY IN HONG KONG AND RELATED IMPACT FACTORS

Cloud-to-ground (CG) lightning location data during 2006—2012 along with other relevant data, including meteorological parameters and terrain elevation, are analyzed to explore the characteristics of CG lightning activity in Hong Kong and related impact factors. Results show that the largest number of CG lightning strokes was detected in 2010 and the smallest number in 2011. The number of the days with high CG lightning frequency played a key role in the inter-annual variation of CG lightning activity in Hong Kong. The occurrence of CG lightning mainly concentrated between April and September. Positive correlations were shown between the monthly mean value of CG lightning stroke density and meteorological parameters, including temperature, relative humidity, rainfall and CAPE. The most active time for both positive and negative CG lightning strokes was about 1:00 a.m. Lightning activity on the days with high CG lightning frequency, variation of solar radiation and differences in the thermodynamic characteristics between land and ocean were the main factors that affected the daily variation. In terms of spatial distribution, positive CG lightning stroke density over western areas was much higher than that over eastern areas, and areas with high negative CG lightning stroke density were mainly located around mountainous areas with high terrain elevation. Both positive and negative CG lightning stroke density showed a positive correlation with terrain elevation, and spatial distribution of negative CG lightning stroke density around six typical mountains showed a strong similarity with that of terrain elevation.