六盘山区两次切变线过程的地闪特征及其与雷达回波对比的观测

OBSERVATION OF CG FLASH CHARACTERISTICS AND THEIR CORRELATIONS WITH RADAR ECHO FOR TWO SHEAR LINES OVER LIUPAN MOUNTAIN AREA

中文摘要:

      采用改进的交叉环磁场天线定位技术,结合使用3cm天气雷达,1984年夏,在六盘山区进行了关于地闪特征及其与雷达回波对比的观测。对7月31日和8月11日两次过程作了初步的统计分析。结果表明:反射率因子在40dBz以下时,全过程平均地闪频率与反射率因子成正相关;不同活跃程度的雷暴过程对应不同的平均地闪频率;地闪集聚区与PPI廓线之间的配置随云体的演变、移动而变化;云内入流区和山区迎风坡处可能更易集聚地闪。地闪的首次回击的众数峰值电流约为2×10⁴A。另外的一些个例值为:正闪在地闪中所占比例约为14%,并且在雷暴过程结束时升高,可达41%;总闪与地闪之比约为2.44。

英文摘要:

      By DFs and radar, data of CG (Cloud-to-Ground) flash and radar echo of two shear line processes were collected in the summer of 1984 in Liupan Mounlain area. Primary analyses have been proceeded from data collected for the shear lines on July, 31 and August, 11.The results show that the mean CG flash rate for the whole storm process is in consistent with reflectivity factor (when echo intensity<40 dBz) and the activity of thunderstorms. Matching between high flash rate areas and radar cells varies widely with the development and movement of clouds. There may be higher CG rate in the area of updraft and mountain slope facing the wind. The estimated mode peak current for the first return strokes is about 2 × 10⁴A. Other results from the two cases are described.