【作者】 李建通； 郭林； 杨洪平；

【Author】 LI Jian-Tong1, 2, 3, GUO Lin2, and YANG Hong-Ping4 1 Institute of Atmospheric Physics,Chinese Academy of Sciences Beijing 100029 2 Xiamen Meteorological Bureau, Xiamen,Fujian 361012 3 Graduate School of the Chinese Academy of Science,Beijing 100049 4 Institute of Heavy Rainfall,China Meteorological Administrator, Wuhan 430000

【机构】 中国科学院大气物理研究所； 厦门市气象局； 中国气象局武汉暴雨研究所；

【摘要】 在雷达-雨量计联合估测区域降水量中,参加校准的雷达初值场代表性好坏在很大程度上影响了最终的估测精度和雨量分布。作者从参加校准的雷达初值场的基本要求出发,分析了先前几种预处理方法的优缺点,提出一种新的资料预处理方法——时间权重平均法,并用1996~1997年的雷达和地面雨量站实测资料进行了分析。结果表明:该方法充分考虑了雷达和雨量计观测的时间一致性,能够在一定程度上改善雷达估测降水的初值场,提高了估测区域降水量的精度。更多还原

【Abstract】 It has been the focus for meteorologist to estimate the distribution and amount of regional rainfall by using weather radar, but previous work mainly depended on the statistic relationship between radar reflectivity factor (Z) and rainfall rate (I). Since 1970’s, taking the advantages of the radar detection which can continuously monitor the large area rainfall and its distribution, and the rain-gauge with high accuracy of rainfall measurement at particular spot, much efforts have been put on the study on combining radar and rainfall-gauge to estimate regional rainfall. However, the performance of the radar initial field used for calibration largely affects the ultimate accuracy of estimation and rainfall distribution in this combination. Thus, this paper focuses on the capability of the radar initial field to describe the spatial distribution of the rainfall, which is very important for improving the precision of estimating area rainfall by radar and rain-gauge. In the estimation of area rainfall using the combination of Radar and gauge, the representativeness of the Radar initial field used for calibration largely affect the ultimate accuracy of estimation and distribution of rainfall. The capability of the radar initial field to describe the spatial distribution of the rainfall is examined in this paper, which is very important for improving the precision of estimating area rainfall by radar and rain-gauge. After analyzing the disadvantage of the initial field of radar data formed by using the four previously methods- plan position indicator’s (PPI) product of low angle, constant altitude plan-positionindicator’s product of three kilometer, PPI’s product of Hybrid Scan, and profiles of radar reflectivity. We find that the time-consistency is not considered enough in above four methods. Therefore, based on the demands of initial field, a new method for forming the initial field of radar data----Time Weight Average (TWA) Method is proposed. The theoretical analysis of the new method indicates that it can overcome the random error of the radar initial field and eliminate the influence of ground clutter on the estimation precision to some extend. Furthermore, it can recover the actual rainfall distribution in the area without the radar echo due to blocking effect of ground-based target, and reflect the migration of the rainfall echo. As a result, the composite radar initial field shows good accordance with the actual rainfall distribution. Analysis of the actual data of radar and gauge collected in 1996-1997 indicates as follows: (1) The TWA method sufficiently considers the time’s consistency between radar detection and the observation of gauge, so it can improve the capability of the radar data to describe the strong center and the spatial distribution of the rainfall. Thus, it meets the demands of estimation area rainfall by radar and rain-gauge on initial field of radar echo. (2) The initial field of radar echo formed using the n更多还原