Persistent transport barrier on the West Florida Shelf

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 c...

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Bibliographic Details
Published in:Geophysical research letters 2006-11, Vol.33 (22), p.L22603-n/a
Main Authors: Olascoaga, M. J., Rypina, I. I., Brown, M. G., Beron‐Vera, F. J., Koçak, H., Brand, L. E., Halliwell, G. R., Shay, L. K.
Format: Article
Language:English
Subjects:
Biological and Chemical
Chaos
Continental shelf and slope processes
Earth sciences
Earth, ocean, space
Exact sciences and technology
forbidden zone
Lagrangian coherent structure
Nonlinear Geophysics
Oceanography
Physical
Phytoplankton
transport barrier
Turbulence, diffusion, and mixing processes
Upper ocean and mixed layer processes
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Summary: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 compute Lagrangian coherent structures (LCSs), which reveal the presence of a 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 × 80 km region on the WFS off Tampa Bay is also used to compute LCSs, and these also reveal the presence of 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.
ISSN:0094-8276
1944-8007
DOI:10.1029/2006GL027800