Submesoscale and Surface Gravity Wave Interactions on the Continental Shelf

University Of California-Los Angeles, Los Angeles CA

Investigators

Abstract

The region spanning the shoreline to the shelf-break serves as a primary connection between human activity at the land-sea interface and ecological functioning farther offshore. An arising conception is that the shelf is filled with nonlinear, 3D flow patterns that are 0.1 - 1 km in spatial scale with ephemeral lifecycles of hours to days, termed ‘submesoscale’. This project will use a multi-scale modeling approach to examine 1) wave effects on submesoscale dynamics and 2) interactions between different classes of submesoscale features. The gained physical knowledge will transform notions of nearshore transport that imprint onto pollution dispersal, coastal biogeochemical fluxes, and ecosystem functioning. New physical understanding will inform management of nearshore marine ecosystems and water-quality in recreational areas through communication with local managers. Results will be disseminated to the general public and historically underrepresented youth through coordination with the Surfrider Foundation. Research collaborations will aid in the development of an online wave-circulation model coupling; strengthen the physical oceanographic and technological framework of a multi-institutional project on the farming of giant kelp on the continental shelf; and modernize conceptions of coastal connectivity for the Long Term Ecological Research Project on giant kelp in the Santa Barbara Channel. This project explores surface gravity wave effects on- and interactions between- the variety of submesoscale coherent structures that uniquely coexist in the region spanning the shoreline to the shelfbreak, including surface layer density fronts and filaments, topographic wakes, internal tidal bores, freshwater plumes, and surfzone vortices. The primary hypotheses are: (1) surface gravity wave effects on currents can significantly modify the local circulation, material fluxes, and spatial orientation of nearshore submesoscale coherent structures and (2) the coexistence of distinct phenomena drives submesoscale interactions that manifest as (a) sporadic collisions between individual fronts or vortices and (b) competition to regulate stratification and material fluxes. Tools include a suite of high-resolution, multiply-nested ROMS simulations employing non-hydrostatic capability and realistic atmospheric, tidal, and surface wave-averaged forcing, and complementary idealized simulations to target the fundamental dynamics and parametric dependencies of these interactions. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.