High-Frequency Variability Induced in the Southern California Bight by a Wind Event in Sebastián Vizcaíno Bay, Baja California

Abstract

Although the California Current System extends as far south as the southern tip of the Baja California Peninsula (BCP), some past model domains have employed an open boundary near the Mexico-US border, excluding Sebastián Vizcaíno Bay (SVB), a hook-like coastal feature at mid-length of the BCP. An earlier modeling study has shown the SVB to be a previously unknown forcing region that governs SSH variability in the Southern California Bight (SCB). Motivated by that evidence, our aim is to understand the variability that originates from the SVB and to identify what is lost in a numerical model of the SCB when the SVB is excluded. To do this we use an idealized configuration of the MITgcm, without tides, using the bathymetry with the bay and comparing it to model runs where the bay is removed. Our results show that a short wind event (≤4 hr) blowing over SVB can enhance variability everywhere in the domain. First, the event excites a seiche in the bay at frequency 5.2 cpd. Then, seiche energy leaks into the domain in the form of gravity waves that are topographically amplified in the SCB, coastal trapped waves (CTWs) that travel north along the coast, and internal waves, that enhance vertical velocity variance at particular depths by up to 27% compared to experiments without the SVB. Given the frequency of wind events like the one modeled, our results suggest that the SVB is a continuous source of gravity waves, internal waves, and CTWs to the SCB.