Comparing Scatterometric and Radiometric Simulations With Geophysical Model Functions to Tune a Sea Wave Spectrum Model

A unified approach to simulate both microwave radiometric and scatterometric observations over a sea surface based on the two-scale electromagnetic scattering model has been implemented. The simulations have been compared with empirically derived geophysical model functions (GMFs) for the purpose of tuning the electromagnetic forward model and the embedded sea surface characterization and wave spectrum. The comparison has concerned a large number of wind speeds, frequencies, and observation angles for both the passive and active cases. Two widely adopted literature spectra have been used as benchmarks. A new expression for the hydrodynamic modulation function has been developed too. The proposed new spectrum has allowed us to reproduce both the passive and active GMFs´ behaviors fairly well, generally improving the agreement yielded by literature models, particularly for scatterometric simulations.