Wind retrieval capability of rotating, range-gated, fan-beam spaceborn scatterometer

The primary mission of a wind scatterometer is to determine wind speed and direction over the ocean. This is achieved by performing a set of radar cross-section measurements at different azimuth view-angles over the resolution cell, and inverting the backscatter model, a so-called geophysical model function (GMF), to extract the wind information using the azimuth anisotropy of the radar backscatter by sea-surface in presence of wind. A new concept of rotating fanbeam radar was introduced which operates in C-band. The present paper describes an analysis of the new concept by means of wind retrieval simulations and an investigation of advanced features such as multi-beam, dual-polarisation, dual-frequency and polarimetric capabilities in improving the wind retrieval accuracy. End-to-end simulations of the complete system are performed starting from wind-fields which are sampled by the scatterometer model. The simulated radar echos are then converted to sets of backscattering coefficients (sigma-naught) which are inverted to obtain again the wind-fields containing measurement errors and noise. The performance of the system is assessed by analysing the quality of retrieved wind as functions of the instrument configuration and characteristics (parameters).