Chapter Seven 



LINEAR THEORIES OF 

 THE GULF STREAM 



Perhaps the most striking feature of the large-scale horizontal surface 

 circulation in the North Atlantic Ocean is its east-west asymmetry. 

 Although the mean winds are very broad and diffuse over the entire ocean, 

 the currents along the western shores of the Atlantic are very narrow and 

 intense. This same westward intensification of surface currents is observed 

 in other oceans, and has been the object of study by the writer (Stommel, 

 1948), who proposed that the latitudinal variation of the Coriohs parameter 

 was the cause of the asymmetry, and by Munk (1950), who first developed 

 a thorough dynamical theory which yields the main features of the ocean 

 circulation and the correct order of magnitude of the transports of ocean 

 currents from the computed wind-stress distribution. 



The Kuroshio is the counterpart of the Gulf Stream in the North Pacific. 

 In the Indian Ocean the Agulhas Current hugs the coast of Africa. In the 

 South Atlantic there is the Brazil Current. The coastlines and areas of these 

 oceans are quite different, so we are tempted to think that local bathy- 

 graphic pecuharities are not an essential influence in the western intensifi- 

 cation of ocean currents; thus the existence of the Straits of Florida is not 

 essential to the formation of the Gulf Stream. If the Antilles were excavated 

 the Gulf Stream would still exist. However, the South Pacific Ocean offers a 

 somewhat embarrassing exception. There does not appear to be any current 

 of great intensity off Austraha; in fact, the Humboldt Current off Peru is the 

 strongest South Pacific current, and it hes in the eastern part of the South 

 Pacific. With this important exception the following rule does seem to hold: 



6-2 



