江苏雷暴大风双偏振雷达特征统计分析

detail/32.1803.P.20230913.1120.004.html Analysis of Dual-Polarization Radar Characteristics of Thunderstorm Gales in Jiangsu Province

关键词:  雷暴大风  环境参数  双偏振雷达

Key words:  thunderstorm gale  environmental parameters  dual-polarization radar

摘要:

利用双偏振雷达、地面自动站、闪电定位仪、探空等资料对江苏2012—2022年262次雷暴大风过程的环境参数和2020—2022年41个导致雷暴大风的对流风暴演变特征进行分析。结果表明：（1）雷暴大风发生在大气层结不稳定背景下，850 hPa和 500 hPa温差中位数超过 25 °C，对流层中层存在干层；春季动力条件较好，0~6km垂直风切变中位数达到18.4 m·s-1，是夏季的2倍；夏季能量条件较好，CAPE平均值可达2 491.0 J·kg-1，而春季仅为 977.5 J·kg-1。（2）凝练和定量验证了基于双偏振特征量的雷暴大风风暴演变的概念模型：对流风暴的生命史分为 3个阶段，初生阶段存在较强的 ZDR柱，Z和 KDP较弱且未及地；发展阶段 KDP柱显著增强，ZDR柱稍有减弱；雷暴大风发生阶段Z、ZDR和KDP核心高度均明显降低。因此，较强的ZDR柱，并伴随显著增强的KDP柱是雷暴大风发生的前兆信号。（3）统计获得双偏振特征量预警指标：初生阶段和发展阶段多数分别发生在雷暴大风发生前60 min和前20 min；在0~2 km的高度上，3～4 dB 的ZDR大值区提前10~15 min到达雷暴大风站点。

Abstract:

The present study analyzed the environmental parameters of 262 thunderstorm gales in Jiangsu from 2012 to 2022 and the evolution characteristics of 41 convective storms that induced thunderstorm gales in Jiangsu from 2020 to 2022. Data used included sounding data and those from dual-polarization radar, ground automatic stations, and lightning location instruments. The results show that: (1) Thunderstorm gales occurred under the background of unstable atmospheric stratification. The median temperature difference between 850 hPa and 500 hPa exceeded 25 ℃, and there was a dry layer in the middle troposphere. In spring, dynamic conditions were better, and the median 0~6 km vertical wind shear reached 18.4 m · s-1, which was twice that of summer. Energy conditions were better in summer, and the average CAPE could reach 2491 J · kg-1, compared with 977.5 J · kg-1 in spring. (2) The conceptual model of the evolution of thunderstorm gales based on dual-polarization characteristics was developed and quantitatively verified: the life history of convective storms was divided into three stages. In the initial stage, there were strong differential reflectivity (ZDR) columns, and weak reflectivity (Z) and specific differential phase (KDP) that did not reach the ground. In the development stage, the KDP column was significantly enhanced, while the ZDR column was slightly weakened. The core height of Z, ZDR and KDP decreased significantly in the stage of thunderstorm gale. Therefore, a strong ZDR column, accompanied by a significantly enhanced KDP column, is a precursor signal for the occurrence of thunderstorm gales. (3) The early-warning indicators of dual-polarization characteristic parameters were obtained: in most cases, the initial stage and development stage occurred 60 minutes and 20 minutes before the occurrence of thunderstorm gale, respectively. At the height of 0~2 km, the ZDR maximum value area of 3~4 dB reached the thunderstorm gale site 10~15 minutes in advance.