关键词: 多普勒雷达, VAD技术

Abstract: VAD (Velocity-Azimuth Display) technique can retrieve larger scale wind and divergence efficiently. Triple VAD(TVAD) and half VAD technique are an extension of VAD technique, they can get the large-scale mean wind information of different region in radar scan area. In this paper, the error analytic formula of expanded VAD technique (TVAD and half VAD) against VAD technique is obtained in theory. It is proved that harmonic analytic method can be used to calculate the first harmonic coefficient from half circle data accurately and from triple circle data approximately by error theory and simulating test and observed radar data fitting test. So the large-scale winds retrieved by half VAD technique have the same precision as the wind retrieved by VAD technique, and the large-scale winds retrieved by TVAD technique have some error. The error of the large-scale wind retrieved by TVAD technique has some relationship to initial phase of the fitting harmonic curve. The error of wind direction from TVAD technique is 0～20°, relative error of wind speed is 0～0.4. Simulated test of ideal harmonic dispersed data indicates that the average error of wind direction retrieved by TVAD is 16°, relative error of wind speed is 0.27, it is close to the error of conventional wind observation. The fitting test of Doppler velocity-azimuth profile illustrates that the fitting harmonic curve of half VAD technique and TVAD technique can give the characteristic of the large-scale wind field in the calculated area.

Key words: Doppler radar, VAD technique