An investigation of the circulation of the Gulf of Mexico

Abstract

Empirical search and inverse techniques were used to reanalyze historical hydrographic data obtained in the Gulf of Mexico, February 12 to March 31, 1962. From these data, eight transects, which provide basin‐wide coverage of the gulf, were constructed. On the basis of water properties the circulation of the Gulf of Mexico was characterized as a three‐layer, mass‐conservative system. Along most sections an empirical search in density coordinates was sufficient to obtain an optimum reference level that balanced the transport in the three layers. An inverse correction was necessary to obtain a mass balance for those sections that crossed the Loop Current and mesoscale eddies. The density of the optimum reference level (σ1 = 32.17) obtained from this analysis corresponds approximately to the bottom of the Antarctic Intermediate Water layer that exists in the Gulf of Mexico. By using this optimum reference level, total velocity profiles at specific locations in the Gulf of Mexico were obtained. Taken together, these yielded a description of the winter circulation of this region. In general, the large‐scale circulation consists of a clockwise (anticyclonic) gyre which is most prominent in the upper 500 m. Eastward and westward transports associated with the gyre are approximately equal at about 5 × 106 m3 s−1. Variations to this flow are provided by the Loop Current in the eastern gulf and a cyclonic eddy in the northwestern gulf. Transports obtained for these circulation features are approximately 30 × 106 and 8 × 106 m3 s−1, respectively, which are in agreement with values obtained from other hydrographic surveys in the Gulf of Mexico.