Small-Scale Topographic Effects On The Generation Of Along-Shelf Propagating Internal Solitary Waves On The Amazon Shelf

This study investigates along-shelf propagating internal solitary waves (ISWs) on the Amazon Shelf using satellite observations and numerical modeling. These ISWs appear as streak-like patterns in satellite images along a narrow path within the North Brazilian Current (NBC), propagating against the current. The streak-like patterns of the along-shelf propagating ISWs are a result of the quasi-two-dimensional bathymetry below, suggesting the possibility of using sea surface imprints to detect the topographic features beneath. In this study, both the effects of the NBC and tidal current on ISW generation are considered over irregular seafloor. Near-critical conditions (internal Froude number close to 1) created by the joint effects of the NBC and the tides result in ISW generation, while the dominant subcritical conditions result in the upstream propagation of these ISWs. Both the NBC and tidal currents are needed to continuously generate ISWs. This study demonstrates that small-scale topographic features can result in the generation of large numbers of ISWs, which are expected to significantly contribute to ocean mixing and, potentially, sediment resuspension. The ISW-induced current also contributes to sea surface wave breaking as observed by satellites.