多普勒雷达反演风场的风切变识别研究  

WIND SHEAR IDENTIFICATION WITH THE RETRIEVED WIND OF DOPPLER WEATHER RADAR

作　　者：周生辉[1,2] 魏鸣[1,3] 张培昌[1] 张明旭[1] 赵畅[1] 

机构地区：[1]南京信息工程大学气象灾害预报预警与评估协同创新中心,江苏南京210044 [2]河南大学环境与规划学院,河南开封475004 [3]灾害天气国家重点实验室/中国气象科学研究院,北京100081

出　　处：《热带气象学报》2015年第1期119-127,共9页Journal of Tropical Meteorology

基　　金：江苏省普通高校研究生科研创新计划项目(CXZZ12_0501);国家重点基础研究发展计划973项目(2013CB430102);江苏省高校自然科学重大基础研究项目(10KJA170030);国家高技术研究发展计划863项目(2007AA061901;2012AA091801);公益性行业(气象)科研专项(GYHY201206038;GYHY201306040);灾害天气国家重点实验室开放课题(2013LASW-B16);北极阁基金(BJG201208);中国气象局2014年关键技术项目(CMAGJ2014M21);航空科学基金项目(201320R2001);水利部公益性行业科研专项(201201063)共同资助

摘　　要：风切变是风场不均匀的一种表现,这种不均匀恰是造成风场反演困难的主要因素之一,利用多普勒天气雷达的径向风场数据,并基于风场反演的方法对风切变的识别和大小进行了分析和计算。对传统的根据径向风差异去识别风切变的方法分析后,发现风场均匀时径向风速在不同方位角之间会存在差异,并且这种固有差异在径向风场的零速线附近达到最大,从而会造成识别中的误判。针对风切变区风场的不均匀特点,在风场反演中选用了均匀风场模型进行计算,用临近格点之间风矢差来表示风切变的大小。对广州一次强对流过程中风切变的识别结果表明,在连续单体和中尺度气旋的强回波区,切变区主要集中在强对流区,以及移动路径的前侧;风切变的量级显示,在强对流与中尺度气旋处的风切变大小明显大于其它位置处,量级大小一般在4.5m/(s·km)以上,而强对流与中尺度气旋区边缘的切变大小一般在4.0 m/(s·km)以上,并且切变发展的方向与天气过程的一致;对于潜在发展的对流,对比结果发现风切变的大小在3.0 m/(s·km)以上时容易发展成新的单体。分析结果表明,通过对强切变出现的位置和发展趋势进行判断,可为强对流的天气发展起到预警作用。Wind shear reflects that the wind field is not uniform and this non-uniformity is one of the primary factors which make the retrieval of the wind field difficult. Based on radial velocity data from a Doppler weather radar and a wind-field retrieval technique, the presence and size of wind shear are identified in this paper. After analyzing the traditional techniques which rely on the difference of radial velocity to identify wind shear, a fixed difference among radial velocities that may cause false identification in a uniform wind field was found. Near the zero contours of Doppler velocity, the fixed difference reaches the maximum. Because of the non-uniformity in wind shear areas, the difference of retrieval results between surrounding analyzed volumes will be significant when using a uniform model for retrieval, and the difference can be used as a measurement to show how strong the wind shear is. According to the analysis of a severe convective weather process that occurred in Guangdong, in strong echo regions of continuous cells and meso-cyclones, it can be found that the areas where wind shear appeared was with severe convection and a front, with the strength significantly larger than in other regions and the magnitude generally larger than 4,5rnf（s.km）. For the regions at the edge of those severe convective areas, the wind shear strength was larger than 4.0m/（s.km） and its movements were consistent with the weather process. Besides, by comparing the variation of wind shear strength during the convection, it can be found that new cells will be more likely to generate when the strength is above 3.0m/（s·km）. Therefore, the analysis of strong wind shear＇s development is helpful to forecasting severe convection.

关 键 词：大气探测 识别算法 风场反演 风切变 

分 类 号：P415.2[天文地球—大气科学及气象学]