Non-linear wind analysis of single Doppler radar observation in DVAD framework

The application of the distance velocity-azimuth display (DVAD) methodology to retrieve the vertical wind profile from single Doppler radar observations is presented in this study. It was shown that Doppler velocity observations at a constant altitude can be expressed as a single polynomial function for both linear and nonlinear wind fields in DVAD. Only a one-step least squares fitting of a polynomial function is required to obtain the vertical wind profile of a real wind field. The mathematic formulation of DVAD results in two advantages over the traditional nonlinear velocity-azimuth display (VAD) method used for the nonlinear analysis of single Doppler observations. First, the requirement of only one-step least squares fitting leads to robust performance when Doppler velocity observations are contaminated by unevenly distributed data noise and voids. Secondly, the degree of nonlinearity of a real wind field can be directly estimated in DVAD instead of being empirically determined in the traditional method. A proper nonlinear wind model to approximate the real wind field can be objectively derived using the DVAD methodology. The merits of DVAD as a quantitative single Doppler analysis method were compared with the traditional method using both idealized and real datasets. Results show that the simplicity and robust performance of DVAD make it a good candidate for single Doppler retrieval in operational use.