Dynamic Height and Seawater Transport Across the Louisiana-Texas Shelf Break. Final Report




Current, Carole L. and William J. Wiseman, Jr.

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U.S. Department of the Interior, Minerals Management Service, Gulf of Mexico OCS Region


Our study quantifies time dependent, highly vertically resolved geostrophic transport of waters from the Gulf of Mexico across the Louisiana-Texas continental shelf break, and provides a first order picture of the spatial and temporal variability of shelf break exchange processes. Cross-shelf transport is large, and consistent with the findings of Bender and Reid. The annual volume of water transported off the shelf across the shelf break is approximately equal to the total volume of water on the shelf.... The present study begins with the determination of orthogonal patters of pressure anomaly that are characteristic of geostrophic flow, computed from LATEX-A field hydrography and assumed dynamics of the system. Shelf break mooring data then is projected onto these patterns of variability, which are called dynamic vertical structure functions or dynamic modes (Kundu et al. 1975; Flierl 1978; SAIC 1989; Arango and Reid 1990; Current 1993). Estimates of time varying pressure anomaly profiles and dynamic height are produced by the summation of weighted dynamic modes, and estimation of cross-shelf geostrophic transport follows from these profiles by invoking geostrophic balance.


45 pgs.


continental shelf, oceanography, gulf of mexico, mathematical models, ocean circulation, ocean currents