Accuracy of Wind Fields Observed by a Bistatic Doppler Radar Network

Abstract

The accuracy of wind vectors derived from bistatic dual-Doppler synthesis was investigated. The investigation was based on mathematical examinations and observation data analyses in both convective and stratiform cases. Accurate wind vectors were calculated within a range of 40° < ? < 150°, where ? was the bistatic scatter angle. The accuracy is mainly governed by ? as the first principle, while sidelobe contamination and the sensitivity of the low-gain bistatic antenna are practically the main obstacles in retrieving accurate wind fields in convective and stratiform echoes, respectively. The sidelobe contamination around strong convective echoes with large gradients of reflectivity can be eliminated by comparing the measured bistatic reflectivity and a clean bistatic radar reflectivity, which is derived from the measured transmitting radar reflectivity and a bistatic radar equation. The radar equation includes the bistatic resolution volume and a bistatic antenna pattern estimated by the long-time observation of stratiform echoes. The equation also leads to the distribution of minimum detectable reflectivity of the bistatic receiver. The multiple bistatic radar observation in stratiform echoes produced three kinds of horizontal wind vectors, which were almost coincident with each other, in the overdetermined region. The composite wind fields are calculated by a simple variational method.