The present study deals with the investigation of wind velocity observed by the Doppler radar. The first phase of paper is the observation of wind using the Doppler radar. Observations have been carried out by using the Doppler radar which is installed in the suburb of Sapporo, Hokkaido, Japan. Horizontal and vertical wind components are estimated by applying the VAD (Velocity Azimuth Display) method to the Doppler data. We make sure that the VAD method can precisely estimate the wind components. The second phase is the utilization of wind data for investigation of rainfall field. The geostrophic wind observed by the Doppler radar is incorporated into the Kao model so that three dimensional wind components are estimated in the planetary boundary layer. The rainfall field is simulated by applying such wind distribution to the Kessler parameterization. The above methodorogy offers considerable promise for the progress of physics-based rainfall models and forecast methods.