PIn. I. An operational nonlinear physical inversion algorithm for precipitable and cloud liquid water estimate in nonraining conditions over sea

Abstract—An operational nonlinear Physical Inversion (PIn) algorithm for precipitable and cloud liquid water estimate is described. It is suited for a generic conical scanning satellite microwave radiometer acquisitions over sea, in non-raining conditions. The algorithm does not need any calibration phase, and is independent from the availability of in-situ data, being consistent in different geographical and climatological situations. Adopted formulation is addressed to provide observational data to help validating water vapour and cloud fields produced by a numerical weather prediction model. Furthermore, such technique can be utilised for global reanalyses purposes, improving estimates of primary fields of hydrological cycle. A sensitivity study of the forward model and a comparison between output brightness temperatures and those from a robust numerical code are also reported: achieved discrepancies result acceptable with respect to instrumental constrains and computation time.