Publication Date

Fall 2025

Degree Type

Thesis

Degree Name

Master of Science (MS)

Department

Moss Landing Marine Laboratories

Advisor

Tom Connolly; Dustin Carroll; Maxime Grand

Abstract

The goal of this study is to investigate fine-scale Lagrangian coherent structure (LCS) generation in a coastal upwelling setting with prominent topography using a high-resolution global-ocean circulation model (LLC4320). I examine LCS properties, spatiotemporal evolution and vertical structure, as well as possible connections to submesoscale variability and chlorophyll. The LLC4320 simulation in the Cape Mendocino region is evaluated using high-resolution satellite and other ocean observations. Additionally, this study uses a novel dynamical systems technique by relating the LCS of flow fields to the physical dynamics of the mesoscale-to-submesesoscale transition. It is found that time series of short timescale LCS yield seasonal patterns with distinct excitations of the Rossby number Ro, an indicator of nonlinear dynamics. These periods of heightened Ro are explored through two case studies with elevated vorticity and vertical velocity structures which extend past the mixed layer. The observed counterparts of these case studies are also associated with elevated chlorophyll concentrations. These results indicate that surface-ocean patterns of attracting and repelling LCS are useful tools in diagnosing subsurface submesoscale processes.

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