An advanced variational-based multiple-Doppler radar synthesis technique is developed by which one can analyze the flow field in a domain containing radar baseline(s) and complex topography. The retrieved three-dimensional wind fields from this method satisfy a simplifed vertical vorticity equation, thus they can be applied directly for vorticity budget diagnosis, and improving the accuracy of the thermodynamic retrieval. This method is capable of using data simultaneously from any number of radars.
Two real case studies are conducted. In the first case, this algorithm is utilized to explore the evolution of the precipitating rainband over Taiwan as Typhoon Morakot (2009) impinged on the island on 8 August 2009. The rainfall spatial distribution is discussed, and the wind field characteristics over the mountainous area are revealed and explained. In the second case, this method is able to use multiple-radar observations to identify a re-intensified eyewall of typhoon Fanapi (2010) after passing over the Central Mountain Range (CMR). Possible mechanisms for this inland eyewall re-intensification are proposed.