Circulation over the Texas-Louisiana slope based on sea surface elevation and current velocity fields /
Surface circulation patterns over the Texas-Louisiana shelf
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| Format: | Thesis Book |
| Language: | English |
| Published: |
[Place of publication not identified] :
[publisher not identified] ;
1997.
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| Subjects: | |
| Online Access: | http://proxy.library.tamu.edu/login?url=http://proquest.umi.com/pqdweb?did=736823891&sid=1&Fmt=2&clientId=2945&RQT=309&VName=PQD |
| Summary: | Surface circulation patterns over the Texas-Louisiana shelf edge/slope were studied using twelve data sets collected between April 1992 and November 1994. Fields of water elevation and current velocity were produced by blending current measurements with surface geopotential anomaly relative to 400 db (GA) or altimeter-derived sea surface height anomaly (SSHA). The fields were represented by a series of trigonometric structure functions with both east- west and north-south harmonics. The basic series represented the water elevation field; the current velocity field was a derivative of the basic series. The cost function consisted of a linear combination of the two series. Coefficients were evaluated using least squares regression. SSHA and GA data were significantly correlated in water depths >200 m. Correlations in shallower water were poor, due possibly to pycnobathic effects not included in GA computations or to spatial/temporal scales used in SSHA sampling/processing that were too long for the shelf regime. Fitted fields using SSHA exhibited the general features of GA-based fields. The correlation coefficient of the fitted fields was 0.1 greater than that of actual SSHA or GA data. Fitted velocity fields were consistent with flows expected from water elevation fields. Vector correlations between actual and fitted currents had phases of 2︢[] and squared correlation coefficients of 0.8. Thus, the methodology of trigonometric structure functions efficiently and accurately blended current data with GA or SSHA data to enhance water elevation and current velocity fields. Low-frequency circulation patterns were dominated by Loop Current eddies and associated cyclonic eddies. The largest water elevations and strongest currents were associated with eddies. Cross-shelf-edge transport associated with eddies were substantial. Transports were not preferentially directed onshelf or offshelf, but depended on what eddy sector was in closest proximity to the shelf edge. Loop Current eddies were tracked through time; their size and shape were determined. |
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| Item Description: | Vita. "Major Subject: Oceanography". |
| Physical Description: | xiv, 145 leaves : illustrations, maps ; 28 cm. Issued also on microfiche from University Microfilms Inc. |
| Bibliography: | Includes bibliographical references: pages 106-113. |