南京大学Ying Wa Chan等人近日取得一项新成果。他们报道了三维风场和X波段相控阵天气雷达的双极化信号，在诊断对流风暴垂直运动和云起电中的应用。相关论文于2024年9月12日发表于《大气科学进展》。

香港天文台于2021年在沙螺湾风廓线观测站安装了一台X波段双极化相控阵天气雷达(PAWR)，以监测香港的高影响天气。PAWR可以在1分钟内完成一次空间分辨率为30米的体积扫描。

本研究利用SLW PAWR的差分反射率(ZDR)和特定微分相位(KDP)双极化变量以及水文分类(HCL)产品，来诊断中尺度对流风暴(MCS)的垂直运动和闪电特征。研究人员通过变分资料同化，构建了三维风场，验证了SLW-PAWR观测结果。本研究对分别发生在2022年9月18日和2023年6月17日的两次MCS事件进行了解析。

结果表明，(1)负ZDR很好地指示了与MCS相关的强下沉气流的发生，这也得到了三维风场分析结果的支持；(2)负KDP表明垂直排列的冰晶的形成促进了云的通电；(3)HCL产品表明0°C融化层上方存在混合冰晶和霰，促进了活跃的云对云和云对地闪电。研究结果强调，SLW PAWR提供了必要的观测数据，结合三维风场分析有助于加强对MCS动力学和电气化过程的理解。

附：英文原文

Title: Application of three-dimensional wind fields and dual-polarisation signals of an X-band Phased Array Weather Radar in diagnosing vertical motion and cloud electrification of convective storms

Author: Ying Wa Chan, Haiqin Chen, Churui Chen, Yuanyuan Xu, P. W. Chan, Kun Zhao, Zhengwei Yang

Issue&Volume: 2024-09-12

Abstract: The Hong Kong Observatory (HKO) installed an X-band dual-polarisation Phased Array Weather Radar (PAWR) at its wind profiler station at Sha Lo Wan (SLW) in 2021 for monitoring high impact weather in Hong Kong. The PAWR could complete a volume scan in 1 minute with a spatial resolution of 30 metres. Dual polarimetric variables from the SLW PAWR including differential reflectivity (ZDR) and specific differential phase (KDP) as well as hydro-classification (HCL) products were used to diagnose the vertical motion and lightning characteristics of mesoscale convective storms (MCS). Through variational data assimilation, three-dimensional (3-D) wind fields were constructed to validate the SLW PAWR observations. Two MCS events occurred on 18 September 2022 and 17 June 2023 respectively have been studied. It was found that (1) negative ZDR gave a good indication to the occurrence of intense downdraft associated with the MCS which was also supported by the 3-D wind field analysis results, (2) negative KDP suggested the formation of vertically aligned ice crystals which facilitated cloud electrification, and (3) HCL products indicated the presence of mixed ice crystals and graupels above the 0°C melting layer which promoted active cloud-to-cloud and cloud-to-ground lightnings. These results show that the SLW PAWR provides essential observations which coupled with 3-D wind field analysis can aid to enhance understanding of the dynamics and electrification process of MCS.

DOI: 10.1007/s00376-024-3286-8

Source: http://www.iapjournals.ac.cn/aas/en/article/doi/10.1007/s00376-024-3286-8viewType=HTML