Validation Support of the ERIM Ocean Model

The ERIM Ocean Model EOM is a comprehensive program for the simulation of SAR images of the ocean surface. EOM was delivered to NRL and integrated into the NASE Modeling System in 1991. The purpose of the NASE-EOM module is to simulate ocean surface effects as seen by SAR sensors. The purpose of the validation phase of the NASE-EOM project was to determine which of EOMs physics are reliable and which physics need improvement. To that end, a series of validation tests were run using NASE-EOM. For the Code-to-Theory test, the action spectral density equation was solved in EOM and compared with the linear solution. The results showed some numerical diffusion in EOMs solution which were reduced with finer spectral grid spacing. The Code-to-Code Comparison consisted of a series of feature tables. The final validation test was the Code- to-Data comparison. The 11 test cases were run on the NASE Modeling System at NRL and the simulations were compared to experimental data. The simulated SAR signals were similar to each other and to the data for most test case, but the simulated clutter had different appearances in the SAR codes due to differences in the simulation of the propagation of the waves during the SAR imaging time, the averaging to reduce the speckle, and the angular dependence of the equilibrium wave height spectrum. SAR, Simulation, Ocean surface hydrodynamics.