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Persistent Transport Barrier on the West Florida Shelf

M. J. Olascoaga·I. I. Rypina·M. G. Brown·F. J. Beron-Vera·H. Koçak·L. E. Brand·G. R. Halliwell·L. K. Shay
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Abstract

Analysis of drifter trajectories in the Gulf of Mexico has revealed the existence of a region on the southern portion of the West Florida Shelf (WFS) that is not visited by drifters that are released outside of the region. This so-called ``forbidden zone'' (FZ) suggests the existence of a persistent cross-shelf transport barrier on the southern portion of the WFS. In this letter a year-long record of surface currents produced by a Hybrid-Coordinate Ocean Model simulation of the WFS is used to identify Lagrangian coherent structures (LCSs), which reveal the presence of a robust and persistent cross-shelf transport barrier in approximately the same location as the boundary of the FZ. The location of the cross-shelf transport barrier undergoes a seasonal oscillation, being closer to the coast in the summer than in the winter. A month-long record of surface currents inferred from high-frequency (HF) radar measurements in a roughly 60 km $\times$ 80 km region on the WFS off Tampa Bay is also used to identify LCSs, which reveal the presence of robust transient transport barriers. While the HF-radar-derived transport barriers cannot be unambiguously linked to the boundary of the FZ, this analysis does demonstrate the feasibility of monitoring transport barriers on the WFS using a HF-radar-based measurement system. The implications of a persistent cross-shelf transport barrier on the WFS for the development of harmful algal blooms on the shoreward side of the barrier are considered.

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M. J. Olascoaga, I. I. Rypina, M. G. Brown, F. J. Beron-Vera, H. Koçak, L. E. Brand, G. R. Halliwell, L. K. Shay. 2006-08-07. Persistent Transport Barrier on the West Florida Shelf. https://doi.org/10.1029/2006gl027800

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