The impact of thermal stratification and wind stress on sea surface features in SAR imagery

We have conducted high-resolution numerical experiments with the computational fluid dynamics (CFD) software ANSYS FLUENT on the dynamics of centerline ship wakes and rain-formed plumes in the presence of wind stress. The ship wake model is initialized with the velocity field from numerical simulations using a model with a ship hull and propellers. We then apply wind stress perpendicular to the centerline wake. We simulate SAR images with a radar imaging algorithm using the surface velocity field produced by the CFD model. Results show ship wake asymmetry since the wind stress enhances flow convergence upwind of the centerline wake and reduces it on the downwind side. The results are qualitatively consistent with available SAR images. We added a near-surface thermal stratification (e.g., diurnal thermocline) to the model during initialization and investigated the impact on the ship wake hydrodynamics. Stratification appears to influence the spreading of the wake, while the circulation in the wake can bring colder water to the surface. For the plume simulation, we initialize the model with a low-density plume imitating randomly distributed rainfall. The plume structure also shows asymmetry relative to the wind direction in simulated radar images.