基于C-FMCW雷达的高原夏季对流云垂直结构分析研究  

Research of the Vertical Structure of Summer Convective Precipiation Cloud over the Qinghai-Tibetan Plateau by C-FMCW Radar

作　　者：阮悦 阮征[2] 魏鸣[1] 葛润生[2] 李丰[2] 金龙[4] 

机构地区：[1]南京信息工程大学,江苏南京210044 [2]中国气象科学研究院灾害天气国家重点实验室,北京100081 [3]福建省气象台.福建福州350001 [4]河北省气象技术装备中心.河北石家庄050021

出　　处：《高原气象》2018年第1期93-105,共13页Plateau Meteorology

基　　金：国家自然科学基金项目(41475029); 公益性行业(气象)科研专项(GYHY201406001)

摘　　要：第三次青藏高原观测试验中C波段垂直探测雷达于2014年7-8月在西藏那曲地区进行了连续探测,对获取的降水云廓线数据进行处理分析得到37个对流云体,提取包括对流强度CI(大气上升运动与下沉运动差)、云顶高度Hctop、35 d BZ回波区顶高Hz35、最大回波强度Zmax等13个特征参数。运用模糊聚类分析方法对对流降水云体特征参数进行深厚和浅薄对流云分类,其中Hctop和Hz35分类清晰,与CI分类的相似度超过0.8,使用一致性较好的三个特征参数CI、Hctop、Hz35对37个对流降水云进行聚类分析,得到9个深厚对流降水云体和28个浅薄对流降水云体。深厚对流云体中CI最大达到33 m·s-1、Hctop最深为12 km、Hz35高于5 km(距地高度AGL,下同);浅薄对流云中CI平均仅14 m·s-1、Hctop平均为2.5 km。在深厚对流云中0.8~1.5 km高度处常出现类似零度层亮带的回波强度和径向速度加强层,浅薄对流云体此特征不明显。结合天气雷达回波分析,深厚对流云体的水平分布多表现为对流单体嵌入到降水系统中,而浅薄对流云体则表现为孤立的爆米花分布。9次深厚对流累积地面降水量82.7 mm,占7-8月总降水量的28%,多伴有冰雹出现;28次浅薄对流累积地面降水量28.7 mm,降水贡献远小于深厚对流云。During the Third Qinghai-Tibetan Plateau Atmospheric Scientific Experiment III, the precipitation clouds in Nagqu, Tibet was continuously detected with C-FMCW radar from July to August 2014. The dataset gained was then analyzed, as a consequences of which, 37 convective clouds is obtained; further, 13 characteris- tic parameters were extracted, including Convective Index （ difference of updafts and downdrafts, CI）, the max- imum cloud top（ Hctop）, the maximum height of 35 dBZ （ Hz35 ）, the maximum reflectivity （ Zmax ） , etc. The cluster analysis method was applied for categorization of all these characteristic parameter in terms of deep and shallow convective cloud. From which, it is found that the parameters of Hctop and Hz35 are most favorable for the classification, with a similarity of more than 0. 8 to that of CI. In addition, the parameters of CI, Hz35 and Hctop, which are in possession of relatively excellent consistency, were employed for a cluster analysis, then the 37 clouds were identified as 9 deep convective precipitation clouds and 28 shallow convective precipitation clouds. For the deep convective clouds, the maximum of CI is up to 33 m ~ s-1 , as well as maximum Hctop of 12.5 km and Hz35 of higher than 5 km（ above ground level, hereinafter the same）. While, for the shallow con- vective precipitation clouds, the average of CI and Hctop are 14 m ~ s-1 and 2. 5 km, respectively. In the deep convective clouds, a steady layer similar to the Bright Band often appeared at the height of about 0. 8 N 1.5km, which is however not applicable to the shallow convective clouds. Based on the C-FMCW radar, it is believed that the horizontal distribution of the deep convective clouds was mainly manifested as organizing multi-monomer into convective precipitation system, and shallow convective clouds showed a distribution like individual scatter- ing popcorn. The 9 deep convection clouds resulted in a accumulated ground rainfall of 82. 7 mm, accounting for 28% of the whole rainfall of the very t

关 键 词：青藏高原 C-FMCW雷达 对流云分类 大气垂直速度 

分 类 号：P412.25[天文地球—大气科学及气象学]