PHYSICAL OCEANOGRAPHY OF THE GULF OF MEXICO 



By Dale F. Leipper, Agricultural and Mechanical College of Texas 



Oceanography may be defined as the study of 

 the oceans in all their aspects, including the 

 interrelationships betweea the seas and their 

 boundaries — the atmosphere, the shoreline, and 

 the sea bottom. Physical oceanography consists 

 of the analysis of the physical properties of sea 

 water, the study of motions in the oceans such as 

 those associated with ocean waves, tides, and 

 winds, and examinations of the various mecha- 

 nisms for the transfer and interchange of energy. 



The nature of physical oceanography differs 

 from that of the other aspects of the subject in 

 that certain mvestigations may be conducted 

 somewhat independently. The other generally 

 recognized aspects of oceanography are the bio- 

 logical, the chemical, the geological, and the meteor- 

 ological. Investigations in these are usually 

 dependent upon physical oceanography and upon 

 each other. It is desirable that work in the 

 physical aspect be planned jointly with that in the 

 other aspects in order that maximum utilization 

 may be made of results which are obtained. 

 The physical oceanograplier must pay particular 

 attention to the problems in the other branches 

 of the work since one of the primary objectives 

 of his own researches is the development of 

 information needed for the solution of some of 

 these problems. 



There are many unique opportunities in the 

 study of physical oceanography in the Gulf of 

 Mexico. There is an offshore oil industry facing 

 many problems related to construction and opera- 

 tion in the shallow waters over the wide conti- 

 nental shelf, there is a huge chemical industry 

 which has an output depending heavily upon the 

 varying longshore currents which alter the salt 

 content of the water at the position where it 

 is taken into the plants, and there are many 

 characteristic weather features such as hurricanes. 



' Contribution from the Department of Oceanography of the Agricultural 

 and Mechanical College of Texas, Oceanographic Series No. 16; based in 

 part on investigations conducted for the Texas A. and M. Research Founda- 

 tion, through the sponsorship of the U. S. Navy Office of Naval Research. 



squalls, and fog which result from effects of the 

 oceans upon the atmosphere. Further, the large 

 oyster and shrimp fisheries are markedly affected 

 by currents, turbulence and the physical charac- 

 teristics of the sea water. Also, in reduction of 

 beach contamination, prevention of beach erosion, 

 reduction of dredging costs in marine channels, 

 increasing the efficiency of marine transportation, 

 development of recreational areas on the beaches, 

 and in providing oceanographic information critical 

 to the defense of our coastline, physical oceanog- 

 raphy plays a most important role in the Gulf of 

 Mexico. 



The Gulf, being nearly enclosed, provides a 

 model ocean in which much may be learned about 

 processes operating in the larger oceans which are 

 not so readily adaptable to comprehensive and 

 systematic analysis. The presence of fixed plat- 

 forms far from shore may make it possible for the 

 first time to make such determinations as that of 

 the effect of the wind in changing the slope of the 

 sea surface in the open sea. Such information is 

 needed for further development of the theories of 

 wind stress upon the sea surface and for the more 

 complete understanding of the manner in which 

 the winds drive the ocean currents and set up 

 ocean waves. 



Despite the need for physical information in 

 the Gulf, relatively little has as yet been done to 

 survey the region systematically and to provide 

 information in a form which is generally available. 

 Recently there have been increased efforts in this 

 direction, and within the near future it may be 

 expected that knowledge of this highly important 

 oceanic region will be greatly increased. 



OCEAN CURRENTS 



The primary problem in the physical ocean- 

 ography of any region is the determination of the 

 ocean cuiTents. In the Gulf of Mexico it is par- 

 ticularly difficult. To provide a background for 

 a discussion of this problem it is well to consider 



119 



