X波段相控阵天气雷达对流过程观测 外场试验及初步结果分析

中国气象科学研究院灾害天气国家重点实验室与安徽四创电子股份有限公司联合研发了专门用于快速观测对流过程、具有多波束观测能力的X波段相控阵天气雷达(XPAR),并利用该雷达与C波段双线偏振雷达(CPOL)于2013年4~6月在广东省江门市鹤山站进行了对比观测试验,以检验该雷达观测模式及其对快速变化的对流云演变过程的观测能力,为进一步改进雷达观测模式提供依据。本文首先介绍了XPAR的主要技术指标和观测模式,利用实测数据对比分析了三种观测模式观测的回波结构、灵敏度,并与C波段双线偏振雷达数据进行了对比,详细分析了2013年5月30日一次中尺度线状对流系统后部的单体的发展和消亡过程,讨论了XPAR分钟级数据在分析对流过程演变中的作用。结果表明:(1)XPAR三种观测模式获取的降水回波结构合理,实现了在1 min内完成一个高空间分辨率的体扫的探测功能,数据的时空分辨率远远高于现有的机械扫描雷达;(2)XPAR的精细观测模式数据揭示了单体触发、发展和演变过程,清晰给出了两次径向辐合发展过程及其与回波发展的关系,给出了新一代天气雷达和C波段双线偏振雷达不能提供的新的事实;(3)XPAR分钟级数据对进一步认识对流单体内部γ中尺度及其更小尺度系统的发展和演变有非常大的帮助。

Field Experiment on Convective Precipitation by X-Band Phased-Array Radar and Preliminary Results

Developed by the State Key Laboratory of Severe Weather, the Chinese Academy of Meteorological Sciences, and Anhui Sun-Create Electronics Ltd. Co., X-band phased-array radar (XPAR) was combined with C-band polarization radar (CPOL) to observe convective precipitation in Heshan, Jiangmen district, Guangzhou, from April to June 2013. S-band operational radar (SA) data were also collected to examine the reflectivity bias of XPAR. In this study, the work modes and observation capability for convective precipitation are examined to improve the radar performances. The characteristics of XPAR and work mode are first introduced in this paper, and the precipitation structures and reflectivity sensitivities by three work modes are compared with those by CPOL and SA. XPAR data with temporal resolution of 1 min are used to analyze the genesis and evolution of convective cell that developed in the rear of a convection line on May 30, 2013. The results indicate that XPAR can capture the main characteristics of 3D structures of precipitation with the three work modes and can complete one volume scan within 1 min with higher temporal and spatial resolutions than that by CPOL and SA. Moreover, the XPAR data with fine mode can reveal the initiation and evolution of convective cells in detail, in addition to two convergence zones and their relationships with reflectivity structures, which could not be observed by CPOL and SA. Further, the XPAR data with high temporal and spatial resolutions are helpful for improving the understanding of the meso-γ and additional detailed structures in convective systems.