Relationship between cloud characteristics and radar reflectivity based on aircraft and cloud radar co-observations     

宗蓉  刘黎平  银燕 《大气科学进展》2013,30(5):1275-1286

Cloud properties were investigated based on aircraft and cloud radar co-observation conducted at Yitong, Jilin, Northeast China. The aircraft provided in situ measurements of cloud droplet size distribution, while the millimeter-wavelength cloud radar vertically scanned the same cloud that the aircraft penetrated. The reflectivity factor calculated from aircraft measurements was compared in detail with simultaneous radar observations. The results showed that the two reflectivities were comparable in warm clouds, but in ice cloud there were more differences, which were probably associated with the occurrence of liquid water. The acceptable agreement between reflectivities obtained in water cloud confirmed that it is feasible to derive cloud properties by using aircraft data, and hence for cloud radar to remotely sense cloud properties. Based on the dataset collected in warm clouds, the threshold of reflectivity to diagnose drizzle and cloud particles was studied by analyses of the probability distribution function of reflectivity from cloud particles and drizzle drops. The relationship between reflectivity factor (Z) and cloud liquid water content (LWC) was also derived from data on both cloud particles and drizzle. In comparison with cloud droplets, the relationship for drizzle was blurred by many scatter points and thus was less evident. However, these scatters could be partly removed by filtering out the drop size distribution with a large ratio of reflectivity and large extinction coefficient but small effective radius. Empirical relationships of Z-LWC for both cloud particles and drizzle could then be derived.  相似文献   

SWAN系统中雷达反射率因子质量控制算法及其应用   总被引：4，自引：0，他引：4  

吴涛  万玉发  沃伟锋  冷亮 《气象科技》2013,41(5):809-817

介绍了SWAN系统中雷达反射率因子质量控制算法原理,包括数据预处理、孤立噪声回波过滤、超折射回波抑制3部分.数据预处理将原始雷达资料转换为统一的RD20格式,并检测数据质量.孤立噪声回波过滤包括双向搜索、回波特征量过滤法.超折射（Anomalous Propagation,AP）回波抑制采用模糊逻辑原理.介绍算法配置参数,通过对比分析武汉、随州、西安雷达AP识别因子概率分布图可知,三者是类似的,表明默认参数的适用性.评估表明,该方法可过滤掉大部分AP回波,缺点是未能识别部分远距离AP回波以及错误识别部分降水回波.  相似文献   

Finite integral solution for the point source response of a layered acoustic medium     

M. Tygel  P. Hubral 《Geophysical Journal International》1986,84(3):647-651

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Maximum Kurtosis Phase Correction   总被引：1，自引：0，他引：1  

R. E. White 《Geophysical Journal International》1988,95(2):371-389

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X波段多参数气象雷达对强风暴云雷电个例的探测研究     

崔丹  肖辉  王振会  何宇翔  秦元明 《南京气象学院学报》2009,32(6):839-850

利用多普勒双偏振多参数气象雷达,结合地面LD-Ⅱ闪电定位仪资料,对一次中尺度对流强风暴云的雷电过程进行观测分析。结果表明,闪电发生前后,对流云上部的差分传播相移率KDP、差分反射率因子ZDR和差相移φDP有明显的变化,反映出云中冰相粒子排列取向随云中电场分布结构的变化而变化。这种闪电发生时冰相粒子排列取向存在明显变化的信息,说明用多参数气象雷达探测的技术以及开展雷电预警预报是可行的。  相似文献   

一次局地暴雨过程的多普勒雷达特征分析   总被引：1，自引：1，他引：0  

彭军  高卫飞  张琼 《沙漠与绿洲气象(新疆气象)》2010,4(1):28-31

利用库尔勒多普勒天气雷达资料,对2008年5月发生在新疆巴州焉耆盆地的一次局地暴雨过程的回波特征进行分析。降水过程中,在库尔勒到焉耆盆地一带先后有两次飑线发展东移,是造成局地暴雨的中小尺度系统。径向速度所反映的在库尔勒到焉耆盆地一带低空存在明显的垂直风切变,雷达西南方向长时间维持西南气流,为暴雨提供了水汽辐合及垂直向上输送的动力条件。  相似文献   

Study of Methods for Three-Dimensional Multiple-Radar Reflectivity Mosaics          下载免费PDF全文

XIA Yanjiao  LIU Liping  SHI Yan 《Acta Meteorologica Sinica》2008,22(3)

This paper investigated several approaches to remapping and combining multiple-radar reflectivity fields onto a unified 3D Cartesian grid with high spatial and temporal resolutions,and analyzed systematic ob servation differences among multiple radars.The remapping approaches were evaluated by inspecting the spatial consistency of the reflectivity fields on vertical and horizontal cross sections on the equidistant line of radars,and the intensity change of 1-h accumulated precipitation before and after interpolation.The com bining approaches were evaluated by continuity examination.The results show that for remapping schemes,the vertical interpolation with nearest neighbor on the range-azimuth plane is the most reasonable scheme that provides consecutive reflectivity fields and retains the high-resolution structure comparable to that of the raw data;for multiple-radar data mosaics,the distance-exponential-weighted mean scheme provides spatially consistent reflectivity mosaics.The mosaics call mitigate various problems caused by the radar beam geometry such as the cone of silence.  相似文献   

华北回流天气多普勒雷达径向速度分布特征   总被引：4，自引：0，他引：4  

张守保  张迎新  王福侠  裴玉杰 《气象》2008,34(2):33-37

使用多普勒雷达资料对四次华北回流天气过程进行了分析,结果表明:(1)回波具有较大水平范围的、连绵成片的均匀幕状特征.回波顶较平整,回流降雨过程中还存在零度层亮带.属层状云降水回波.(2)速度图上,在零速度线两侧常分布范围较大数值不等的正负径向速度中心,低空零速度线呈"S"型,风随高度顺时针旋转,有暖平流存在.在强降水时段出现前常伴有区域性的冷平流层.(3)风廓线图上,从低层到高层由东北风转为西南风,风向发生了近180度的顺时针旋转,存在强垂直切变.降水开始与结束时分别表现为低层偏东风与中高层西南气流叠加、低层偏东风与中高层西南气流任何一者消失.边界层顶部出现浅薄的冷平流层是降水强度加强的信号.  相似文献   

多普勒雷达资料在中尺度模式短时预报中的应用   总被引：1，自引：1，他引：0  

智协飞  高洁  张小玲 《气象科学》2010,30(2):143-150

将国内新一代多普勒雷达基数据Lev-Ⅱ的9个仰角的原始反射率和径向风资料应用于中尺度模式ARPS(the Advanced Regional Prediction System),通过对2007年7月18日济南短时特大暴雨过程的个例研究,分析了雷达资料对初始场的改进效果及其对模拟结果的影响。结果表明,同时利用雷达反射率和径向风资料改进过的初始场能明显改善中尺度数值模式短时定量降水预报。对比风场发现,雷达径向风调整后在初始场中出现明显的中小尺度特征,能减少模式的spin-up时间。随着积分的进行,对水汽场的调节也有一定作用,但相对于风场调节不够显著。雷达反射率主要是改进初始场中的湿度参数,增加初始场中云水等含量。积分开始后,对风场调整也很显著。此次模拟,控制试验较好地预报出雷达回波的分布和水汽中心,对应的降水落区与实况也较为接近,但对雷达回波中心强度的预报略大,相应地降水量的预报也偏大。  相似文献   

2006-06-13贵州省望谟县大暴雨的诊断分析   总被引：4，自引：0，他引：4  

李登文  杨静  乔琪 《南京气象学院学报》2008,31(4):511-519

利用NCEP／NCAR再分析资料、观测资料、FY-2C的红外云图TBB资料以及多普勒雷达的实时监测资料,对2006年6月13日发生在贵州省望谟县的突发大暴雨天气进行了研究,综合分析了此次强降水天气过程的影响系统、中尺度对流云团的发生发展演变、雷达回波特征及物理量场特征。结果表明,望谟县的短时强降水是受河套冷空气快速南下影响而致使贵州中部的辐合线南压锋生诱发β中尺度云团的生成与强烈发展所引起的。强降水区域与低层辐合带直接相关;对流层低层有能量锋出现,锋前积聚较强的潜在湿有效位能,在斜压扰动下,激发了倾斜垂直涡度的发展,导致大气层结对流性不稳定强烈发展,使中尺度对流系统得以发展和维持;雷达回波图反映了典型的中尺度系统特征。  相似文献