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Texas-Louisiana shelf connectivity and time variability using particle tracking

Kristen Thyng
January 27, 2014

Texas-Louisiana shelf connectivity and time variability using particle tracking

Poster presented at the Gulf of Mexico Research Institute (GOMRI) oil spill conference in Mobile, AL, in January 2014.

Kristen Thyng

January 27, 2014
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  1. Texas-Louisiana Shelf
    Connectivity and Time
    Variability using Particle
    Tracking
    Kristen M. Thyng and Robert D. Hetland
    Oceanography, Texas A&M University, [email protected]
    Goal
    Understand the factors affecting cross-shelf transport on the Texas-Louisiana shelf for application
    to oil spill transport to the coastline
    TX-LA shelf numerical grid with other GISR grids
    Starting locations of numerical drifters: 5km spacing
    [green dots]
    Example drifter tracks from two locations
    [green (red) circles: start (end) locations, cyan/purple lines: tracks]
    Where do drifters travel in the domain? Do they cross the shelf?
    Does this change seasonally? What does it depend on?
    ⇒ Address with summarizing histograms
    Numerical Model
    • Regional Ocean Modeling System (ROMS) circulation model of the
    Texas-Louisiana shelf
    • Includes wind and rivers, nested in HYCOM Gulf model
    • Validation: (Zhang et al., 2012a,b)
    Particle Tracker
    • TRACMASS, runs trajectories natively on staggered Arakawa C
    grid (D¨

    os et al., 2013)
    • ...wrapped in Python: TracPy
    (https://github.com/kthyng/tracpy)
    Simulations
    • Started weekly sets of drifters seeded 5 km apart in x and y which
    ran for 30 days
    • 2004-2010
    • Surface-limited
    • Included diffusion to the particle trajectories with AH = 5 m2s−1
    References


    os, K., Kjellsson, J., and J¨
    onsson, B. (2013). Tracmass - A La-
    grangian trajectory model. In Preventive Methods for Coastal Pro-
    tection, pages 225–249. Springer.
    Zhang, X., Hetland, R. D., Marta-Almeida, M., and DiMarco,
    S. F. (2012a). A numerical investigation of the Mississippi and
    Atchafalaya freshwater transport, filling and flushing times on
    the Texas-Louisiana Shelf. Journal of Geophysical Research,
    117(C11):C11009.
    Zhang, X., Marta-Almeida, M., and Hetland, R. D. (2012b). A
    high-resolution pre-operational forecast model of circulation on the
    Texas-Louisiana continental shelf and slope. Journal of Opera-
    tional Oceanography, 5(1):19–34.
    2014 Gulf of Mexico Oil Spill and Ecosystem Science Conference, January 26–29, 2014, Mobile, Alabama

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  2. Probability drifters leaving an area will cross the shelf at some point
    Conclusions
    • Seasonal winds and river water affect cross-shelf transport
    • Stronger coastal cross-shelf connection in summmer
    • Coast is more likely to be affect by off-shore spills in the summer than the winter
    Location of trans-shelf drifters after 30 days
    Probability of drifters reaching the Chenier plain
    Probability of drifters reaching the TX coastline
    Probability of drifters reaching the LA coastline
    Acknowledgments
    This research was made possible by a grant from BP/The Gulf of Mexico Research Initiative
    2014 Gulf of Mexico Oil Spill and Ecosystem Science Conference, January 26–29, 2014, Mobile, Alabama

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