[Eoas-seminar] Doctoral Defense - Ilkyeong Ma

[eoas-seminar at lists.fsu.edu]

Hi all,

Please join us for Ilkyeong Ma's Doctoral Defense on Friday, February 20th, 2026 at 1:00 PM. Located in EOAS 3067.

Title: Impact of Bottom Drag and Caribbean Mesoscale Variability on Ocean Dynamics of the Gulf of Mexico


Name: Ilkyeong Ma

Date: Friday, February 20th 1:00-3:00pm

Major Professor: Eric Chassignet
Location: EOAS 3067


Abstract: The Gulf of Mexico (GoM) circulation is dominated by the Loop Current (LC) and the episodic shedding of Loop Current eddies (LCEs), which drive mesoscale variability and redistribute heat, salt, and momentum across the basin. Accurate simulation of LC variability and LCE shedding is essential because errors in LC configuration and shedding statistics can distort the spatial distribution of eddy kinetic energy (EKE).

This dissertation examines two key regulators of LC variability and mesoscale energetics: (i) bottom drag as a pathway of frictional dissipation and (ii) upstream mesoscale variability from the Caribbean Sea, including the role of surface current feedback (CF). The analysis is based on a 22-year (1994-2015) 1/12° HYCOM integration and a suite of sensitivity experiments that systematically modify bottom drag, boundary-imposed variability, and air-sea coupling.

Results show that bottom drag acts not only as a local energy sink but also as a basin-scale regulator by controlling LCE strength, shedding frequency, and propagation pathways. Its vertical and spatial distribution strongly influences LC configuration and downstream EKE patterns. Upstream Caribbean variability shapes shedding latitude and LC extension; suppressing this variability alters the distribution of LC states and basin-wide energy levels. Incorporating CF provides additional damping that lowers mesoscale energy and modifies LC/LCE statistics.

Together, these findings demonstrate that realistic simulation of the LC system requires consistent representation of both frictional dissipation and upstream mesoscale forcing. By linking bottom drag, boundary variability, and air-sea interaction to shifts in LC configuration, shedding latitude, eddy intensity, and basin-scale energetics, this work provides a process-based framework for improving eddy-resolving simulations of the GoM.

Best,
Adea

Adea Arrison
Sr. Academic Program Specialist
Department of Earth, Ocean & Atmospheric Science
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