College - Author 1
College of Science and Mathematics
Department - Author 1
Degree Name - Author 1
BS in Physics
Ryan Walter, College of Science and Mathematics, Physics Department
In eastern boundary current systems, wind-driven coastal upwelling is the dominant diver of physical, chemical, and biological variability. Near coastal embayments, complex circulation patterns develop during upwelling forcing, and time-dependent descriptions of these patterns for smaller systems (i.e., width and length scales ≤ 20 km) are limited. In this study, we analyze surface and subsurface current patterns in relation to upwelling wind forcing in San Luis Obispo (SLO) Bay, a small coastal upwelling embayment in central California, to investigate the formation and evolution of an upwelling jet and surface current convergence region during a large upwelling-relaxation event. We found that the offshore upwelling jet advected onshore once the upwelling winds reached 5 m/s, and this coincided with the formation of a strong surface convergence region across the mouth of the bay. A particle tracking model revealed enhanced nearshore retention of particles released at the surface following the formation of a strong convergence region. Once the upwelling winds decreased, the upwelling jet reattached to the offshore equatorward jet and the convergence region decreased substantially. When the upwelling winds decreased to below 5 m/s, the convergence zone fully dissipated and the water mass inside the bay was flushed out. The formation, evolution, and persistence of the convergence zone at the mouth of SLO Bay has important biological and ecological implications; however, more realizations are required to fully characterize the spin-up and evolution across different upwelling events and seasons.