中国区域闪电分布和闪电气候的特点

Characteristics of Lightning Distribution and Lightning Climate for China Region

利用1998年1月1日到2003年12月31日TRMM卫星探测到18～38°N、74～123°E闪电资料,对中国区域年、季、日发生闪电频数和随经纬度变化,闪电密度分布和闪电气候特征进行了计算分析。结果表明:中国陆地区年均日发生总闪电数约54600次,白天占到54.47%,夜间占到45.53%,昼夜比为1.2。日闪电频数的年变化是双峰值,闪电主要发生在4～9月,占年总闪电的92%。4月中到5月中旬为次峰值,主峰值在7月中到8月中旬,占年总闪电的43.4%,夏季6～8月占到60%,11月到次年2月发生闪电很少,仅占年总闪电的0.4%以下。日变化以单峰值为主,峰值范围宽,年均每小时达到2275次左右,傍晚18时达到最高峰值,占到日出现闪电的9.1%,上午9～11时达到日变化的最低谷,仅占日出现闪电总的3%,闪电峰值是低谷的12倍,说明中国区域闪电高发时间主要在傍晚。中国区域年均发生闪电频数随纬度的变化要比随经度的变化大,沿海的陆地区出现闪电频数比内陆区高,内陆区比海区高,东部比西部高的特点。4个季节发生闪电峰值的日变化时间表明,不同季节出现闪电峰值的日时段不同,冬季主要在中午,秋季主要在下午,春季主要在晚间,夏季主要在傍晚。中国区域年均白天、夜间和昼夜不同闪电密度分布表明,东部比西部高,闪电高密度区相对较集中。区域对比说明。

Using lightning data detected by the TRMM satellite between 18～30 °N and 74～123 °E from 1998 Jan , 1 to 2003 Dec, 31, the yearly, seasonal and diurnal lightning number and their change with the longitude and latitude, the lightning density distribution and lightning climatic feature were calculated and analyzed in this paper. Results show that the total mean diurnal lightning number is about 54 600 in Chinese land area, and it is 54.47% of the total number during daytime and 45.53% during night time, and their ratio is 1.2. The yearly variety of the diurnal flash number is a pair of peak value , the flash occurs primarily in April to September, and the number is about 92% of the total lightning number in a year. First peak occurs in mid-April to mid-May and the second in June to August, and the second peak is 43.4% of the total yearly lightning number, the flash number in summer (Jun to Aug) is 60% of the total yearly number , and it is only about 0.4% in November to February of the next year. Diurnal variation presents the single peak, and its range is large, mean hourly flash number is about 2 275 in a year, it reaches a maximum at 18:00 P.M. and it's about 9.1% of the diurnal number, it comes to a minimum at 9:00～11:00 A.M. and it's only 3% of the diurnal number, and the maximum is 12 times of the minimum, these show that lightning occurring frequently in Chinese district is primarily in dusk. Diurnal variation presents the single peak, the range of the peak is broad, mean hourly flash number is about 2 275 in a year, it reaches a maximum at 18:00 P.M. and it's about 9.1% of the diurnal flash number, it comes to a minimum at 9:00～11:00 A.M. and it's only 3% of the number, and the maximum is 12 times of the minimum. The yearly mean flash number change with latitude is bigger than that with longitude in Chinese district, the flash number is more in coastal land area than that in inland area, and it is more in inland area than that in sea area, it is more in eastern region than that in western region. The diurnal changing time of peak value occurring lightning in 4 seasons shows that the time with peak value of flash number during a day is different, in winter it is primarily at noon, in autumn it is in the afternoon, while in spring it is at night and in summer it is at dusk. The different yearly mean flash density distribution in daytime, nighttime and all day in Chinese district show that the density is higher in eastern region than that in western region, the high flash density areas are more concentrated relatively. The high flash density areas in daytime are nearby sea, while they are in inland area during nighttime, and the high density areas in daytime are the low flash density areas during nighttime, and vice versa, but there is no such change in Tibet Plateau. The flash density value and its distribution feature are different in different seasons,in spring the high flash density areas are in south part of China, and the large part of inland are the sub-high flash density area, and the density is relatively low in coastal area . In summer the flash density is higher and the area is larger, the higher density areas are consist with the areas with high yearly mean flash density and they are near sea, while the density in inland area is relatively low. In autumn, the relatively high flash density areas are more scattered, the areas are smaller too, mainly in south littoral. In winter, the density is low and the areas occurring flash are small,mainly in south part of 30 °N and Sichuan basin.