250 



KNAUSS 



[CHAP. 10 



the water to the south of the front was moving northwest at right angles to the 

 frontal line at a speed of two knots (100 cm/sec). The estimated speed of the 

 front, normal to itself over a 14-h period, was one knot. The cold water (which 

 was also more saline) was overrunning the warmer water and plunging down- 

 ward (Fig. 11). The temperature gradient was 3°C in 60 m (Knauss, 1957). 



100 120 



TIME (sec) 



Fig. 11. An equatorial "front" plotted with no vertical exaggeration. Temperature con- 

 tours, shown in degrees Fahrenheit, are based on five bathythermograph observations 

 made while the ship was drifting across the frontal edge. (After Knauss, 1957.) 



6. Conclusions and Speculations 



This discussion of the equatorial circulation has been almost entirely des- 

 criptive and has noted only in passing a few of the many attempts to understand 

 the equatorial circulation on a theoretical basis. There has been in the past a 

 wide gap between the theorists and those who try to understand the oceanic 

 circulation by observing it. Although this gap is obviously easy to understand, 

 it most certainly has been to the disadvantage of all concerned. There are signs 

 that this communication barrier is breaking down. With the advent of high- 

 speed computers, it seems possible that theorists can phrase their problems in 

 ways which do not divorce their solutions so much from reality. On the other 

 hand, it is to be hoped that the marked increase in the oceanic observational 

 program and the steady but slow (sometimes painfully slow) improvement in 

 oceanographic instrumentation will permit descriptive and experimental 

 results which are more meaningful and less ambiguous. 



It would seem that the equatorial region might be a particularly fruitful 

 region in which to study oceanic circulation. For one thing, the circulation is 

 apparently but little influenced by the continental boundaries. This is particu- 

 larly true in the Pacific where the continental boundaries are 8000 miles apart. 

 The gross equatorial circulation pattern in the Atlantic and Pacific are similar, 

 although there are significant differences. The circulation in the Indian Ocean, 

 on the other hand, is very different from that in the Atlantic and Pacific. 

 Furthermore, it is subject to a much more marked seasonal variation than that 

 in either the Atlantic or the Pacific. A careful delineation of the differences as 



