On the circulation of the western Gulf of Mexico with observations from April 1978

In April 1978 the circulation pattern in the western Gulf of Mexico was dominated by a cyclonic circulation feature centered near 25°20'N, 95°20'W and an anticyclonic circulation feature centered near 23°30'N, 95°50'W. The north‐south scales of both gyres are approximately 225 km, while the east‐west scales are greater than 450 km. An eastward geostrophic transport of 29.7 × 10 6 m 3 /s is found between the centers of the cyclone and the anticyclone. We believe that both the anticyclone and the cyclone migrated to the western Gulf from the Loop Current region of the eastern Gulf. The anticyclone is probably supplemented by a wind‐driven circulation as described by Blaha and Sturges, and an eastward extension of the wind‐driven current which flows to the south along the lower Texas shelf may intensify the cyclone and/or anticyclone. Also, this extension of the Texas shelf current may tend to confine the anticyclone to the south and the cyclone to the north of the current's location.