暴雨的多普勒天气雷达速度辐合风场特征  

Echo Characteristics of Doppler Velocity in a Torrential Event

作　　者：王彦[1,2] 吕江津[1] 周海光[2] 王丽荣[3] 吴彬贵[1] 

机构地区：[1]天津市气象台,300074 [2]中国气象科学研究院灾害天气国家重点实验室 [3]河北省石家庄市气象局

出　　处：《气象》2008年第3期63-68,132,共7页Meteorological Monthly

基　　金：天津市科委应用基础研究面上项目(07JCYBJC12800);中国气象科学研究院灾害天气国家重点实验室(2005LASW02);公益行业项目(GYHY200706004);国家自然科学基金(40475017)共同资助

摘　　要：多普勒天气雷达探测大范围强降水时,其多普勒速度回波特征既不同于单纯的暖(冷)平流的特征(S或反S形)也不同于纯粹的大尺度辐合(散)运动特征(弓状),而是暖(冷)平流和辐合(散)两种运动相结合的风场(称之为复合风场)所产生的多普勒速度特征。应用天津塘沽新一代天气雷达资料,并结合自动气象站资料和改进的EVAD技术,分析2005年8月16日发生在海河流域的一次大范围、长时间的强降雨天气过程的多普勒天气雷达资料。结果表明:(1)当低层出现暖平流和辐合运动相结合的复合风场特征时,即多普勒天气雷达速度场产品表现为自雷达中心开始,在同一距离圈上,一侧的零速度线弯向正速度区的顺转程度明显大于另一侧的零速度线弯向负速度区的顺转程度,即负速度区面积大于正速度区的面积时,降水就增强或维持。(2)当低层出现暖平流和辐散运动相结合的复合风场特征时,对应降水减弱或停止。这种对雷达速度场的辐合辐散分析将对大范围强降水的形成、发展、维持和消散具有很好的临近预报指示作用。Doppler radar, when used in detecting large-scale intense precipitation, has its echo features differing from the warm or cold advection alone （as an S-or anti-S-shape） and also differing from the large-scale convergence or divergence （as a bow-like shape）. The features of Doppler velocity resulting from the combination of warm or cold advection with convergence or di- vergence are called the complex wind-field. Based on the Doppler weather radar data in Tanggu, AWS data and EVAD technique, analysis of Doppler weather radar data from an extensive, persistent strong rainfall event over the Hai river basin on August 16, 2005 was conducted and gave the following results： （1） In the presence of a low-level complex wind-field related to the combination of warm advection and convergence, it can be seen from the Doppler velocity products that, starting from the radar center, the clock-wise curvature of a zero-speed line on one side toward the positive velocity zone is more remarkable than the counterpart on the other side towards the negative velocity zone, implying that when the negative speed zone is bigger compared to the maximum positive area, rainfall is reinforced or maintained; （2） In the presence of a low-level complex wind-field resulting from warm advection combined with divergence, the precipitation would be weakened or ceased. Therefore, the study on the convergence and divergence in the radar velocity field gives a good indicator of nowcasting for the formation, development, maintenance and decay phases of a large-scale rainfall event.

关 键 词：暴雨 多普勒天气雷达资料 径向速度场 EVAD技术 

分 类 号：P445[天文地球—大气科学及气象学] TN959.4[电子电信—信号与信息处理]