中国内陆高原地闪特征的统计分析

Analyese on Some Features of Ground Flashes in Chinese Inland Plateau

利用微秒级时间分辨率的宽带慢天线电场变化仪首次在中国内陆高原地区对雷暴过程中的正、负地闪特征进行了测量和系统分析 ,发现每次雷暴过程中正闪的比例有随总闪频数增大而减少的趋势 ,弱雷暴过程更有利于正地闪的产生。平均来讲 ,正地闪占闪电总数的 16 % ,介于美国夏季雷暴和日本冬季雷暴之间。负地闪闪击间隔的算术平均值和几何平均值分别为 6 4.3ms和 46 .6ms。 5 4%的负地闪有至少一次继后回击强度大于首次回击 ,而且有 2 0 %的继后回击其强度大于首次回击强度。继后回击强度与首次回击强度的比例几何平均值为 0 .46 ,算术平均值为 0 .70 ,平均回击数为 3.76 ,39.8%为单次回击地闪。正地闪的多次回击只占 13.0 % ,且闪击之间的时间间隔也较大 ,算术平均值为 91.7ms。

Characteristics of both positive and negative ground flashes in Chinese inland plateau were measured and analyzed by recording the electric fields generated by the whole flash in microsecond resolution. The ratio of positive ground flash to total flash had a tendency of increasing with total ground flash number. It is 16% in average which fallen between winter thunderstorm of Japan and summer thunderstorm of United States. For negative ground flashes the geometric and arithmetic mean of the interstroke intervals were 64.3 ms and 46.6 ms. It was found that 54% of the negative multiple-stroke ground flashes had at least one subsequent stroke with a peak electric field larger than that of the first return stroke. Furthermore, about 20% of the subsequent stroke had peak electric field amplitudes larger than those of the first return strokes. The geometric mean of the ratio of the subsequent stoke peak field to the first return stroke peak field was 0.46. The mean number of stokes per flash was 3.76 and 39.8% of the flash were single-stroke flashes. For the positive flashes, only 13.0% of the flash were multi-stroke flashes, and the interstroke interval is 91.7 ms.