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Measurements on lightning in Chinese inland plateau area

中国内陆高原地区闪电测量

基本信息

批准号：
08041122
负责人：
WATANABE Teiji
金额：
$ 2.18万
依托单位：
Gifu University
依托单位国家：
日本
项目类别：
Grant-in-Aid for international Scientific Research
财政年份：
1996
资助国家：
日本
起止时间：
1996 至无数据
项目状态：
已结题

项目摘要

A comprehensive observation on lightning occurred in an inner land plateau area called Lanzhou, northwest of China, was conducted during July 1 to August 20 of 1996. Data including simultaneous 5-station slow electric field changes, lightning video photos as well as radar echoes was obtained. Following are some primary results we have got by using this data :1. Concerning the thunderstorms in summer in the inner land plateau area of China, the percentage of positive cloud-to-ground (CG) discharge over all of the CG discharge was higher than that in other place, and varied with thunderstorms. It seems that the above property did not depend on the height of-10 C temperature layr or the maturity of thunderstorms.2. Statistical characteristics, such as multiple-strike number and the slow front risetime of an electric waveform produced by a return stroke of positive CG discharges, are similar to that of the winter thunderstorms in Hokuriku reported sofar.3. The height of negative charge lay … More r was 3-5km above the ground, which is consistent with the height of-10 C temperature layr. The magnitude of average charges transferred to ground by each strike was about two times of that of negative CG discharges of common summer thunderstorms.4. For the positive CG discharge, the ratio of the lightning whose time difference between the beginning of relative preliminary inter-cloud weak discharge and the occurrent of return stroke was longer than 100 ms was about 60%.5. The occurrence of pulses being company with return strokes varies with the discharge polarity. About 50% of pulses occurred over the time before the return stroke for the negative one, while most of them occurred at the time of return stroke for the positive one.6. The average persistent time of continuous current and the average persistent time of leaders were 38ms and 51ms respectively for positive CG discharges.7. The average risetime of slow front of the first stroke was 11 microsecond for negative discharges and 24 microsecond for the positive one. For the continuing stroke, the average rise-time was 4 microsecond and 14 microsecond for negative and positive respectively. All of them were more than two times longer of those of common summer thunderstorms.8. It seems that there was a close relation between the slow front persistent time of a continuing stroke and the inter-stroke interval time of this strike. The longer the interval time was, the longer the slow front risetime.9. For the continuing stroke, the analysis also indicates that the longer the slow front risetime was, the bigger the amplitude of the stroke electric field change. No such a relationship was found for the first stroke.10. The average ratios of the part of electric field change of slow front over the peak change were 46% and 21% for the first stroke and the continuing stroke respectively for negative discharge, and were 54% and 27% respectively for positive one. All of these percentages are as the same as those of the common summer thunderstorms. Less

1996年7月1日至8月20日对兰州内陆高原地区闪电进行了综合观测。获得了5站同步慢电场变化、闪电视频照片和雷达回波等数据。以下是我们利用这些数据得到的一些初步结果：中国内陆高原地区夏季雷暴中，云对地正流量占总云对地正流量的比例高于其他地区，且随雷暴而变化。上述性质似乎与-10℃温度层的高度和雷暴的成熟度无关。统计特征，如多次打击数和由正CG放电返回冲程产生的电波形的缓慢锋面上升时间，与北陆冬季雷暴报告相似。负电荷高度在地面以上3 ~ 5km处，与10℃温度层高度一致。每次雷击向地面转移的平均电荷量约为夏季雷暴负CG放电的两倍。正向CG放电时，相对初步云间弱放电开始与回波发生时间差大于100 ms的闪电占60%左右。脉冲伴随回冲程的发生随放电极性的不同而不同。约50%的脉冲发生在负向脑卒中前，而大多数脉冲发生在正向脑卒中前。CG正放电时，连续电流的平均持续时间为38ms，先导的平均持续时间为51ms。负放电组第一冲程慢锋平均上升时间为11微秒，正放电组平均上升时间为24微秒。在连续冲程中，阴性和阳性的平均上升时间分别为4微秒和14微秒。所有这些雷暴的持续时间都是普通夏季雷暴的两倍多。连续划水的慢锋持续时间与划水间隔时间之间似乎存在着密切的关系。间隔时间越长，锋面缓慢上升时间越长。对于连续冲程，分析还表明，慢锋上升时间越长，冲程电场变化幅度越大。在第一次中风中没有发现这种关系。负放电时，第一冲程和连续冲程慢锋电场变化部分与峰值变化的平均比值分别为46%和21%，正放电时慢锋电场变化部分与峰值变化的平均比值分别为54%和27%。所有这些百分比与夏季常见雷暴的百分比相同。少