Hydrography of the Stream 



water and the Gulf Stream'. According to these definitions it 

 could equally well be called the 'warm wall' though in neither 

 case do we have anything resembling a wall. This temperature 

 gradient exists at different depths across the entire width of the 

 Gulf Stream and therefore cannot be considered as something 

 separate or adjoining the Stream. Because of the misleading con- 

 notations of the term ' cold wall ' it will not be used in this paper. 



51 



Fig. 27. Sample of temperature sections, in shallow surface layers (upper 

 900 ft.) across the Gulf Stream, made by means of the bathythermograph. This 

 figure is a simplification of a section published bj^ Iselin and Fuglister (1948, 

 fig. 2). The simplification consists of drawing 5° intervals for the isotherms. 

 Temperatures are in degrees Fahrenheit. The section extends from the con- 

 tinental shelf at the left, across the Gulf Stream, where the 65° F. isotherm 

 drops abruptly, well into the Sargasso Sea on the right. Even in this simplified 

 drawing there is a great deal of fine detail. Just what is the cause of these fine 

 variations we do not know, although internal waves are often mentioned as an 

 explanation. The cold filament of water on the left-hand side of the Stream 

 is clearly shown at a depth of between 200 and 300 ft., just left of center. 



MEANDERS AND EDDIES 



The position of the Gulf Stream is not always the same, nor is its path even 

 approximately straight. Church (1937) was able to demonstrate the truth 

 of the former statement conclusively on the basis of 1200 thermograph 

 records from ships crossing the Stream. The number of crossings per week 

 was about three or four, and hence it was impossible to develop any detail 

 about the presence of wavelike disturbances along the Stream, or of eddies 

 on either side. 



Fuglister and Worthington (1951) have prepared a chart showing the 

 positions of the maximum cross-stream temperature gradients at a depth 

 of 100 m., from all bathythermograph surveys made in the five years 1946 

 through 1950 (see fig. 28 of the present study). These lines, of course, show 

 a great deal more detail than Church's. They confirm Church's deduction 

 that the position of the Stream varies from time to time, but, more 

 important, they indicate that the Stream does not shift position bodily, 

 but in wavelike patterns which have come to be spoken of as meanders. 

 The first information on the way in which these meanders move was 



4-2 



