Airborne Remote Sensing of Surface and Internal Wave Processes on the Inner Shelf

The inner shelf, bounded on the shoreward side by the surf zone and offshore by a depth of approximately 50-100 m is a region in which a variety of physical processes can occur over a wide range of time scales (from fractions of a second for wave breaking, to the two-week spring-neap tidal cycle and seasonal cycles), and length scales (millimeters for the wind-stress supporting gravity-capillary waves and other microstructure, to O(10-100 km) of along and across-shelf processes) associated with a wide range of different forcings. In this work, we report on a large field campaign conducted off the coast of Point Sal, CA in September 2017, as part of the Office of Naval Research funded Departmental Research Initiative (DRI) Inner Shelf program. We used a combination of airborne remote sensing techniques along with in-situ surface and subsurface measurements to investigate the role of surface and internal wave processes on the dynamics, transport and mixing in the water column of the inner shelf. Characterization of the directional surface wave field (and wave breaking) from offshore to the beach, and its impact on mass transport to improve numerical wave modeling of the inner shelf is discussed. Additionally, unique quantitative measurements of the interaction of internal waves with surface gravity waves (that leads to the generation of rough and smooth bands of ocean surface, a proxy of internal waves in remote sensing products) are presented, and compared to theoretical predictions.