华南飑线系统对流与层云区闪电起始和通道位置处的云微物理特征

利用广州S波段双偏振雷达观测数据和低频电场探测阵列三维闪电定位数据,分析了2017年5月4日和5月8日华南地区两次飑线过程中闪电起始和通道位置处的雷达偏振参量和降水粒子特征.两次飑线中约80％的闪电起始和通道(统称闪电放电)定位于对流区.对流区闪电放电位置处的雷达反射率(ZH)要比层云区平均大4～5 dBZ,其它偏振参...

CHARACTERISTICS OF CLOUD MICROPHYSICS AT POSITIONS WITH FLASH INITIATIONS AND CHANNELS IN CONVECTION AND STRATIFORM AREAS OF TWO SQUALL LINES

Using data from polarimetric radars and three-dimensional lightning detection, we investigate the characteristics of polarimetric variables and hydrometeors at positions with flash initiations and channels in two squall lines that occurred over Southern China on 4 and 8 May 2017, respectively. It is found that the located lightning pulse discharge events associated with flash initiations and channels (they are collectively called lightning discharges (LDs)) in the convection areas both account for approximately 80%of their respective samples. The average horizontal reflectivity (Z_H) at the radar grid boxes with LDs in the convection areas is about 4~5 dBZ larger than that in the stratiform area, while the average values of other polarimetric variables (differential reflectivity (Z_DR), specific differential phase (K_DP) and co-polar correlation coefficient (CC)) associated with the LDs are similar in the convection and stratiform areas. The median Z_Hat the positions with LDs decreases with increasing altitude. Meanwhile, median Z_DR, K_DP, and CC associated with the LDs keep relatively constant above the -10 ℃layer. Below the -10 ℃layer, median Z_DRand K_DPat positions with LDs distinctly increase with decreasing altitude. Moreover, the average Z_H associated with flash initiations is approximately 1~2 dBZ bigger than that corresponding to the flash channels, whereas, in the convection areas, the peak interval of Z_H associated with flash initiations is 25~30 dBZ, smaller than that corresponding to flash channels (30~35 dBZ). Furthermore, the peak interval of Z_H corresponding to flash initiations and channels is different above and below the -20 ℃ level. The dominant hydrometeors at positions with LDs are graupel and ice crystals in the convection areas, and their areas are analogous; meanwhile, the corresponding dominant hydrometeors are dry snow and ice crystals in the stratiform area, and the area of dry snow is distinctly bigger than that of ice crystals.