Novel Scanning Strategy for Future Spaceborne Doppler Weather Radar With Application to Tropical Cyclones

Severe tropical cyclones (TCs) are one of the most devastating natural disasters along the coastal regions from tropical to temperate zones. Understanding the three-dimensional (3-D) wind fields in TCs helps in assimilating their dynamics and predicting their evolution. Unfortunately, up to now, there is no spaceborne weather radar with Doppler capability to measure the 3-D wind components in the global scale. This paper presents a novel scanning strategy for future spaceborne Doppler weather radar mission to retrieve 3-D wind fields of TCs, which has three downward-pointing (with three different fixed tilt angles) and conically scanning beams. With spaceborne Doppler detection, the radar system enables to measure the vertical motion of hydrometeors, which is important in the estimation of latent heat fluxes and in the study of energy transportation in the structure of TCs on a global scale. A novel scanning strategy is presented and optimized to construct three noncollinear radar observations. Three-dimensional wind fields are retrieved using the least-squares method. A model simulation of TCs is used to validate the proposed scanning strategy. The radar beams of the proposal are able to cover TC's full area of interest. The results demonstrate a suitable accuracy of the proposed scanning strategy on retrieving the TC's 3-D wind fields with a resolution of 10 km × 10 km × 0.25 km grid cell, showing a promising use in the future spaceborne Doppler radar.