Intercomparison of SAR imaging models for upper ocean current boundaries

A review and intercomparison has been performed for numerical simulation models which aim to predict the SAR signatures of upper ocean current frontal features. The specific models whose performance is compared in detail are (i) The ERIM Ocean Model (EOM), developed by the Environmental Research Institute of Michigan and the Naval Research Laboratory, and (ii) the University of Hamburg Satellite Oceanography Group Composite Surface Model (UHSO). Both models compute the two-dimensional spectrum of surface waves, including their interaction with wind and the current field by means of an assumed relaxation to an equilibrium wind-wave spectrum. The EOM model computes the radar backscatter using tilted Bragg scattering plus specular reflection. The UHSO model does not account for specular reflection, but it includes the effect of hydrodynamic modulation of the Bragg waves by longer waves, which leads to an upwind/downwind asymmetry of the backscattered power. As a basis for the comparison, ocean current and meteorological observations from the COAST WATCH ´95 experiment, conducted off the south-western coast of Norway, were used together with SAR data obtained under the ESA ERS-1/2 Tandem AO program