SEASAT III and IV

Abstract : JASON continues its theoretical investigation of understanding the origin of the ship wakes seen by the SEASAT radar. The present effort incorporates the new experimental results from the Georgia Strait and the Gulf of Alaska experiments. These experiments appear to rule out the internal wave hypothesis; they also seem to indicate that the Kelvin Wake (here defined in the most general sense to include non-linear processes as well as interactions with the turbulent wake) is rather different than conventional Kelvin wake theory would predict. Nonetheless, a model which seems to be at least qualitatively reasonable can be constructed. The generation of ship wakes (surface or internal) and their detection by radar is a complicated phenomenology involving various branches of physics, hydrodynamics and oceanography. Nevertheless, with the exception of the inner, small angle part of the Kelvin wake, we believe that the theoretical understanding of the problem is adequate to support the conclusions reached in the report.