The relationship between lightning flash rate and ice-related volume derived from dual-polarization radar
The relationship between lightning flash rate and ice-related volume derived from dual-polarization radar
复制标题
DOI：
10.1016/j.atmosres.2020.105166
复制
发表时间：
2021-01
影响因子：
5.5
通讯作者：
S. Hayashi;Akihito Umehara;N. Nagumo;T. Ushio
中科院分区：
文献类型：
--
作者：
S. Hayashi;Akihito Umehara;N. Nagumo;T. Ushio
为了进行准确的闪电预测和临近预报，阐明云中带电性与微物理特性之间的关系非常重要。使用双偏振多普勒雷达、水凝物分类算法和闪电观测，针对日本关东平原上空的 10 个孤立雷暴案例，研究了雷达衍生的与闪电频率相关的微物理特性，在夏季每 5 分钟进行 351 次雷达体积扫描。在这项研究中，35 dBZ 体积内的冰相关粒子 (V35IC) 显示出与云地闪电 (CG) 相关的最高相关系数 (r= 0.75) 和最低的归一化均方根误差 (NRMSE = 8.3%)，并且与云内闪电的关系也最好 (IC,r= 0.69，NRMSE = 8.1%)。在不考虑微物理颗粒的情况下，V35IC 和 CG 闪光速率之间的相关性优于混合相（0°C 至 −40°C 之间）35 dBZ 体积 (r=0.64) 的相关性。第二好的雷达微物理特性是由所有与冰相关的粒子的雷达网格组成的冰块（r = 0.72）。这些结果表明，除了传统使用的霰和冰雹之外，就雷达衍生特性而言，有效的闪电指示器是与冰相关的粒子体积。雷暴较冷地区（气温低于-10°C）与冰相关的颗粒体积与CG和IC的相关性高于较温暖地区，特别是在IC方面。这些结果与先前研究中已被广泛接受的无感充电理论一致。在雷暴开始前每 5 分钟进行 0 至 -30 分钟的时滞相关分析后，发现 V35IC 的冰相关指数随时间推移相关系数下降最慢（30 分钟内 r= 0.75–0.65），可能适合作为闪电临近预报指标。
To conduct accurate lightning prediction and nowcasting, it is important to clarify the relationship between electrification and microphysical properties in clouds. Using the dual-polarization Doppler radar with the hydrometeor classification algorithm and lightning observation, radar-derived microphysical properties related to lightning flash rate were investigated in terms of 10 isolated thunderstorm cases over the Kanto Plain, Japan, with 351 radar volume scans conducted every 5 min during the summer period. In this study, the ice-related particles within the 35 dBZ volume (V35IC) showed the highest correlation coefficient (r= 0.75) and the lowest normalized root mean square error (NRMSE = 8.3%) in relation to cloud-to-ground lightning (CG), and also best to intra-cloud lightning (IC,r= 0.69, NRMSE = 8.1%). The correlation between V35IC and CG flash rate was better than that of the mixed-phase (between 0 °C and − 40 °C) 35 dBZ volume (r= 0.64), without considering the microphysical particles. The second-best radar-derived microphysical property was the ice mass consisting of the radar grids of all the ice-related particles (r= 0.72). These results suggest that an effective lightning indicator in terms of a radar-derived property is the ice-related particle volume, in addition to the traditionally used graupel and hail. The ice-related particle volume in the colder region of the thunderstorm (air temperature lower than −10 °C) showed a higher correlation with CG and IC than that in the warmer region, especially in terms of IC. These results are consistent with the non-inductive charging theory that has been well accepted in previous studies. Following time-lag correlation analysis from 0 to −30 min every 5 min before thunderstorm initiation, it was found that the ice-related index of V35IC demonstrated the slowest decrease (r= 0.75–0.65 in 30 min) in the correlation coefficient with time lapse and may be suitable as a lightning nowcast indicator.