Impact of model resolution on radar imaging of underwater sand waves

Yu, P.; Zhong, X., and Zhou, Y., 2018. Impact of model resolution on radar imaging of underwater sand waves. Radar sensors are capable of imaging varying sea-surface roughness attributable to divergent and convergent current flow over underwater sand waves. This manifestation can be simulated and explored through a flow model combined with a radar-imaging model by explaining the interaction between bathymetry, currents, and surface waves. Accuracy of numerical models is usually limited by grid resolution; however, a lack of studies is present regarding the influence of grid resolution on the combined flow and radar-imaging model, which can determine the research scale of oceanic phenomena based on radar-imaging theory. To examine the role of grid size on imaging of distinct scales of sand ridges and to ignore other sources of surface-roughness variations in coastal areas, the authors designed an idealized flow model integrated with a radar-imaging model with different resolution. The results indicate that high-resolution synthetic aperture radar (SAR) images may be possible to detect bottom features smaller than 100 m. As the increasing grid resolution, surface-roughness variations can gradually reach a stable phase, indicating that the grid spacing should be elaborately selected according to the scale and complexity of underwater topography to fully present performance of the two-dimensional combined model. This model offers a reference to study the application of a radar-imaging mechanism or to analyze morphological changes based on SAR images and the combined system in coastal areas for future work.