研究期間：10108~10207;The purpose of this project is to study the influence of the topographic effect, from a weather radar observational perspective, on the evolution of the precipitation systems. The first stage of this research is to re-design, develop, and test a variational-based multiple-Doppler radar three-dimensional wind synthesis algorithm, which would allow us to analyze the flow field over a complex terrain. In this method, we will adopt the variational method to minimize a cost function, in which several constraints are implemented. These constrains include the relationship between the radar radial wind and the Cartesian winds, continuity equation, vertical vorticity equation, and a set of top and bottom boundary conditions for horizontal and vertical winds. In addition, the so-called immersed boundary method (IBM) will be employed in order to bring in the topographic effect. In this project, we will apply this newly-designed method to analyze the real cases happening in Taiwan. The major data sources for this project will be the ground-based Doppler radar network in Taiwan, and the NSC-NCU mobile radar (TEAM-R). Through this study, we can have a further understanding of this method’s advantages and weakness, the accuracy of its retrieved results. Most importantly, we are able to investigate the impacts of the topographic effects on the structure and evolution of precipitation systems.