Developing and testing a variational multiple-Doppler radar synthesis method using simulated and SoWMEX/TiMREX data

A multiple-Doppler radar synthesis method is developed to recover the three-dimensional wind field. In this method the solutions are obtained by variationally adjusting the winds to satisfy a series of constraints in weak formats. Among them, the primary ones are the multiple-radar radial velocity observations, anelastic continuity equation, vertical vorticity equation, background wind, and spatial smoothness terms. The retrieved wind products are at two time levels, and can be readily applied to conduct the thermodynamic retrieval, in which the temporal derivates of the wind fields are required.

It is found from a series of experiments that the wind field along and near the radar baseline can still be obtained. Furthermore, if the retrieved winds are applied to infer the thermodynamic fields using the traditional dynamic retrieval method, and an extra sounding (e.g., radiowindsonde or dropwindsonde) is combined in order to specify the horizontal average of the thermodynamic perturbations, the preferable place to release this sounding is within the region of weak rather than strong convections.

This method is tested using the radar data sets collected during SoWMEX/TiMREX (SouthWest Monsoon EXperiment/Terrain-influenced Monsoon Rainfall EXperiment), conducted from May to June, 2008 in Taiwan, and reasonable results are obtained.