EFFECTS OF THE SEBASTIÁN VIZCAÍNO BAY AND BATHYMETRIC IRREGULARITIES ON THE GENERATION AND PROPAGATION OF COASTAL TRAPPED WAVES
In 2014, Verdy et al. identified the Sebastián Vizcaíno bay (SVB), a large coastal feature on the Baja California Peninsula, to be a source of sea surface height (SSH) variability many kilometres further north along the Southern California coast. Later, in 2023 Ramos-Musalem et al. showed that the bay is a source of energy generating, among other waves, northward travelling coastal trapped waves (CTWs). This project aims to further characterize the effects of the SVB and other bathymetric features on the generation and propagation mechanisms of CTWs. Idealised numerical simulations are generated with the Massachusetts Institute of Technology general circulation model. The simulations are varied by including and excluding the bay and applying varied scales of smoothness on the otherwise realistic bathymetry. A short, impulsive wind event is used as initial forcing over the area from 27°N on the Baja California Peninsula up to 35.3 N, in the Southern California Bight, using homogenous stratification.
Code by Kenneth Brink (2018), with the purpose of numerically classifying linearised CTWs, is used to find expected and allowed wave modes in the domain. Using key information from these calculations the MITgcm output signal in SSH and vertical velocity was filtered. This resulted in a clear signal with CTW characteristics: a period of roughly 1 day, phase speeds between 0.2-1.5 m/s and wavelengths around 30-150 km. Smoother bathymetry results in faster waves containing higher energy and less variation along the coast. Variations in characteristics are attributed to uneven bathymetry. Although characteristics from the numerical calculation agree with the MITgcm output, the non-linear variation caused by bathymetric changes is deemed too significant to claim that the linear numerical calculation can represent the observed wave behaviour.
The project will continue interpreting the resulting characteristics and classifying the challenges when modelling complex bathymetry.