摘要
基于2014—2015年5—9月西藏那曲地区多普勒天气雷达数据,结合地闪观测数据,识别雷暴单体样本,统计分析了地闪位置附近的雷达回波分布特征,并研究了高原雷暴的雷达参量与地闪频次的相关关系。结果表明:那曲地区地闪发生位置附近的雷达最大反射率因子呈正态分布,峰值分布区间集中于34～41 dBZ。发生地闪位置附近的20 dBZ回波顶主要集中于11～15 km高度,30 dBZ回波顶高分布的峰值区间则为8.5～12 km。分析表明:表征局地雷暴对流发展强度的雷达参量与地闪频次之间一对一的相关关系较差,但相关性随地闪频次增加而增强。基于雷达参量分段统计得到的对应分段平均地闪频次与雷达参量之间表现出较强相关关系,体现了宏观上闪电活动强度与雷暴发展强度之间的正向关系。其中,基于原始数值进行区间划分的强回波(组合反射率因子不小于30 dBZ)面积与平均地闪频次的线性相关系数达0.75,基于对数数值区间划分的7～11 km累积可降冰含量的对数值和地闪频次的线性相关系数达0.95。文中对比了多个雷达参量和地闪频次线性拟合与幂函数拟合结果,整体上幂函数拟合略好于线性拟合。
Lightning observation may play a key role in the monitoring of deep convection over the Qinghai-Tibet Plateau, especially considering that the wide-range and real-time observation ability of lightning location system. It is firstly necessary to understand the relationship between lightning activity and deep convection features, which, has been rarely concerned in the Qinghai-Tibet Plateau. Using radar data and cloud-toground（CG） lightning data during May —September from 2014 to 2015, correlations between CG lightning and radar parameters of thunderstorms are investigated over Naqu, a county in the middle of the Plateau with relatively strong lightning activity. Continuous spatial regions of radar composite reflectivity above20 dBZ are identified as storm cells at each 6 min radar volume scan, and ＂matching ellipses＂ are used to enclose the scope of cells, and then whether CG lightning flashes fall in ellipses or cells is decided. Cells with lightning and located within 30—100 km of radar center are picked out as thunderstorms. Based on5626 thunderstorm samples, it is summarized that the maximum radar echo, 20 dBZ echo top and 30 dBZ within 5 km of CG flash location exhibit normal distribution, with their peak values ranging from 34 to41 dBZ, 11 to 15 km, and 8. 5 to 12 km, respectively. Meanwhile, the maximum vertical integrated liquid content and the maximum precipitation ice content vertically integrated at 7—11 km both show logarithmic normal distribution. A total of 4719 thunderstorms that possess no less than 30 dBZ reflectivity（a threshold value for the definition of strong reflectivity） are selected for the correlation analysis. Weak correlations between CG lightning frequency and radar parameters are found while are considered as one-to-one relationships. However, correlations enhance prominently when the CG lightning frequency in the thunderstorm increases. The correlation study based on interval segmentations of radar parameters is then made and strong relationships are found, indicati
作者
孟青
樊鹏磊
郑栋
张义军
姚雯
Meng Qing;Fan Penglei;Zheng Dong;Zhang Yijun;Yao Wen(Laboratory of Lightning Physics and Protection Engineering/State Key Laboratory of Severe Chinese Academy of Meteorological Sciences,Beijing 100081;Department of Atmospheric and Oceanic Sciences ＆ Institute of Atmospheric Sciences,Fudan University,Shanghai 200438)
出处
《应用气象学报》
CSCD
北大核心
2018年第5期524-533,共10页
Journal of Applied Meteorological Science
基金
国家自然科学基金项目(91537209
41675005)
中国气象科学研究院基本科研业务费项目(2016Z002)
关键词
青藏高原
地闪
雷达参量
相关关系
the Qinghai-Tibet Plateau
cloud to ground lightning
radar parameters
correlation
