The determination of the sea surface NRCS when corrugated by blowing wind and rainfall: an application to rainfall rate measurements over sea

The prediction of the power backscattered by the sea surface in the presence of rainfall is the object of this paper. An electromagnetic (e.m.) model predicting normalised radar cross section (NRCS) of such a surface, must conveniently account for both the large scale roughness due to the wind and the small scale roughness due to raindrop splashes. While several models are available in the literature for wind-induced roughness, only few experimental results or theoretical studies concerning additional rainfall-induced roughness are available. We describe an e.m. model that accounts for the effects of the raindrop splashes, and discuss some related results. An improved algorithm is then proposed for retrieving rainfall rate profiles by means of spaceborne rain radar, which utilises the relationship between sea NRCS and the rainfall rate.