Modeling of Gulf Stream boundary features in SAR imagery

Current measurements of a Gulf Stream boundary region off Cape Charles, VA, identified two current fronts with shear and convergent flows. Using these measured currents the authors have made predictions of the HH and VV radar return for P-, L-, and C- bands and compared them with simultaneously collected polarimetric SAR data. The ocean wave spectrum is computed using the wave-action equation with a Hughes-type source term. Radar cross sections are derived from the predicted wave field using a composite scattering Bragg model. Across the fronts wind waves are both refracted and shortened leading to modulations in their spectral density which is evident in the radar imagery. These current fronts produce significant densities of breaking waves which cannot be ignored in the radar predictions. The authors estimates of the radar cross section including breaking wave contributions are found to be consistent with the SAR data.<
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