基于大气层结和雷暴演变的闪电和降水关系

Relationship Between Lightning and Precipitation Based on Classification of Atmospheric Stratification and Development of Thunderstorm

  • 摘要: 选取2006—2008年发生在北京及其周边地区的28次雷暴过程,基于大气不稳定度参数和雷达参量对雷暴过程进行分类,分析了不同分类条件下的总闪电活动 (SAFIR3000三维闪电定位系统观测) 和对流降水 (雷达反演) 的关系。结果表明:整体而言,总闪对应降水量的平均值为1.92×107 kg·fl-1。依据对流有效位能和抬升指数对雷暴进行分类的分析表明,较强的不稳定状态对应了较小的总闪对应降水量,同时总闪频次和对流降水量的相关性更好。基于雷达特征参数的分类分析表明,总闪对应降水量在对流运动较弱情况下最小,其次是对流运动较强的情况下,而对流运动适中时最大。

     

    Abstract: A total of 28 thunderstorms occurring in and around Beijing area from 2006 to 2008 are picked to investigate the relationship between total lightning (observed by SAFIR3000) and convective precipitation (by radar inversion). These cases are classified according to parameters of the atmospheric stratification where they are generated and the reflectivity of radar. The quantitative results can provide a reference for the applications of lightning data on severe weather warning and precipitation estimation. The lightning forecast can also be improved by assimilating the relationship between the hydrometeors and the lightning activities to the numerical prediction models. The analysis can extend the application field of the lightning data.The results show that the average convective rain yields per flash is 1.92×107 kg·fl-1 on the whole, while the linear correlation coefficient between the total lightning frequency and convective precipitation is 0.584. Total lightning frequency (expressed by F with the time space being 6 min) can be used to calculate the amount of convective precipitation with the equation R=(2.813×108)+(4.570×106)F. A total of 28 thunderstorms are classified according to the convective available potential energy (ECAP) and lifting index IL of the atmospheric stratification where they are generated. It is explored that strong instability of atmospheric stratification tends to be associated with smaller precipitation and more pronounced correlation between total lightning and precipitation. Of which, the classification of ECAP no less than 1600 J·kg-1 has the correlation coefficient of 0.837, the total lightning frequency can be used to calculate the amount of convective precipitation with the equation of R=(1.620×108)+(5.478×106)F. While the classification of IL no less than 4 K has the correlation coefficient of 0.853, the total lightning frequency can be used to calculate the area of the amount of convective precipitation with the equation of R=(1.530×108)+(6.276×106)F. Another three parameters calculated from radar reflectivity, i.e., maximum height of 20 dBZ reflectivity, maximum reflectivity at 12 km level, and volume ratio of the reflectivity larger than 30 dBZ above 0℃ to the reflectivity larger than 40 dBZ above 0℃, in terms of their radar volume scans. The most pronounced relationships between lightning and precipitation occur in the classification of H20 dBZ < 11.5 km, 25 dBZ ≤f12 km < 35 dBZ, and V40/30 < 0.39, when the correlation coefficients are 0.804, 0.609 and 0.750, respectively. The linear correlation between lightning and precipitation show obvious differences in different classifications. The fitting equations in different classifications are revealed, which will provide references for the application of relationships between lightning and precipitation according to the characteristics of thunderstorm processes.

     

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