GULF OF MEXICO 



125 



exit through the Straits of Florida, without de- 

 viating on the way, or dilTusing any to itself 

 significant amount into the Gulf of Mexico |)roi)er, 

 or receiving any predominant contribution from 

 the Gulf in return." This statement on the one 

 hand and the current pattern shown in figures 34 

 and 35 on the other hand summarize the present 

 divergence of opinion. 



The Mahtl Taylor cruise was made without 

 unprotected thermometers or other reliable means 

 of determining depth of observations. Parr 

 cautions that particularly in the Yucatan Channel 

 and Florida Straits there is sufficient uncertainty 

 of the depths of the Mabd Taylor operations "to 

 make it seem inadvisable to subject them to a 

 form of analysis and comparison in which depth 

 is an essential consideration." Similarly, the 

 Atlantis cruise of 1934, Parr (1937), lacks sub- 

 surface data since the hydrographic cable was 

 lost early in the survey. Thus, the oceanographic 

 data available to Parr were meager. 



Dietrich (1939) reviewed the currents of the 

 Gulf, and his conclusions, although based upon 

 essentially the same data as used by Parr, show 

 considerably more influence by the Gulf Stream 

 upon the general circulation in the Gulf. He 

 discussed the sill depths showing that the Gulf 

 circulation cannot affect the deep water circulation 

 of the Atlantic below about 800 meters. However, 

 the Florida current, which is shallower than this, 

 has considerable effect. 



In 1947 the Atlantis conducted a survey of the 

 northwestern Gulf making 27 hydrographic sta- 

 tions (fig. 36) and 473 bathythermograph observa- 

 tions of temperature. These data have been 

 analyzed by Fred B. Phleger (1951), now of the 

 Scripps Institution of Oceanography of the Uni- 

 versity of California, and have been published by 

 the Geological Society of America. 



The first cruises of the Alaska, oceanographic 

 research vessel of the Fish and Wildlife Service 

 operating on a survey of the Gulf of Mexico with 

 the cooperation of the Department of Oceanog- 

 raphy of Te.xas Agricultural and Mechanical 

 College and the United States Navy, Office of 

 Naval Research, were completed in October 1951 

 (fig. 37). These provide the first complete coverage 

 of the Gulf with information needed to compute 

 the deep water currents. The data from these 

 cruises have been distributed and prelimary anal- 



yses indicate that they support the main fea- 

 tures of llie current pattern shown in figure 34, 



A i)rief description of the currents of the Gulf 

 of Mexico is provided in the United States Coast 

 Pilot (1949): 



Under noriual coiiditioii.s, at all seasons of the year, the 

 great volume of water passing northward through Yucatdn 

 Channel into the Gulf of Mexico, spreads out in various 

 directions. Surface flows set westward across Cainpeche 

 Bank, the (iulf of Canipeche, and the Sigsbee Deep; 

 northwestward toward tlalveston and Port Arthur; 

 north-northwestward toward the Mississippi Passes; and 

 eastward into the Straits of Florida. 



A straight line drawn from Buenavista Key, Western 

 Cuba, to the Mississippi Pas.ses forms an approximate 

 boundary between movements having different directions. 

 West of this line the drift is generally northward or west- 

 ward, while east of it the drift is eastward or southeast- 

 ward toward the Straits of Florida. 



There are northward flows along the west side of the 

 Gulf between Tampico and Corpus Christi in the vicinity 

 of the 100-fathom and 1,000-fathom curves, north of the 

 Sigsbee Deep between the 2,000-fathom and the 100- 

 fathom curves, and along the west coast of Florida. 



In general, the surface circulation is the same at all 

 seasons. There is, however, some .seasonal change in 

 velocity, the flow being generally stronger in spring and 

 summer than in the autumn and winter. 



The current near the Florida Keys is variable and 

 uncertain. 



This description is apparently taken from the 

 Pilot Chart series of the Hydrographic Office 

 (H. O. No. 3500, issued monthly). Another 

 series, H. O. No. 10,690, 1 to 12, Current Charts 

 of the Central American Waters, give resultant 

 direction and velocity for each 1° quadrangle of 

 latitude and longitude. This series has been 

 used by Smith, et al. (1951), to show zones where 

 seasonal convergence or divergence occur. 



Many of the references cited above contain 

 bibliographies pertinent to the Gulf of xMexico. 

 Also, Geyer (1950) lists many useful works. 



In summary, the currents of the Gulf of Mexico 

 and their variations are not specifically known. 

 Studies completed in the past indicate some 

 unusual and interesting features and provide 

 incentive and justification for continued intensive 

 investigation. 



SEA SURFACE TEMPERATURES 



A large number of sea surface temperature ob- 

 servations have been collected at shore stations. 

 Some of these data from locations shown in figure 



