Preliminary Study Of Precipitation Measurement In Blockage Area With Doppler Radar And Echo Tracking By Correlation

Precipitation is not only a kind of essential data to a hydrological or atmospheric numerical model, but also a sort of key information for flood monitoring and warning.Nowadays, rainfall intensity and amount collected by gauges can not reflect the actuality due to gage sparseness. On the other hand, the aforesaid two kinds of data over large area can be estimated with weather radar. However, the accuracy of precipitation estimated with a radar is influenced by the quality of radar dataset.The detective ability of weather radar is controlled by radar system parameters and other factors, such as rainfall type. The surrounding high buildings and mountains also exert an influence on its detective ability. How to retrieving stratus-cloud precipitation behind blockages (blocked by mountains or high buildings) is one of the questions researched in this paper. Such a question can be solved by employing the matched vertical profile of radar reflectivity factor (VPR). In order to evaluate the reliability of precipitation estimation, the radar field within 50 km is divided into 4 areas;hence, four VPRs over these 4 areas can be calculated. From rainfall intensity obtained from gauge measurement, the most matched Z of a VPR is found if a Z-R is assumed. By calculating VPRs just over gauges in blockage, the average VPR over blockage area is then got, then we can use the matched Z at the best matching height for rainfall estimation in blockage area. Error analysis is diagnosed to validate such a correction for blockage area, and extrapolation is adopted on the base of TREC (Tracking Radar Echoes by Correlation) for precipitation forecast in short period (one hour).In the third part (chapter 4-6), the second-level radar product system and software development environment are simply described, then the design of DLL (Dynamic Linked Library) TREC module using Microsoft Visual C++ 6.0 is introduced in detail. At last case study's for precipitation forecast on TREC and error analysis are given for reference.