1. OCEANIC CIRCULATION AND OCEAN- 

 ATMOSPHERE INTERACTIONS 



Oceanic Circulation and the Role of the Atmosphere 



The ocean circulation is one of the 

 primary factors in the heat budget of 

 the world. The circulation is impor- 

 tant not only internally to the ocean 

 but also to the overlying atmosphere 

 and, indeed, to the climate of the 

 entire earth. Together the sea and 

 the air make a huge thermal engine, 

 and it is not possible to understand 

 either without having some compre- 

 hension of the other. Any studies of 

 ocean circulation must inevitably in- 

 volve this coupling with the atmos- 

 phere. 



The Present State of Understanding 



Studies of ocean circulation have 

 progressed a long way in the past 

 fifty years. Measurements of the 

 characteristics of the ocean at great 

 depths have produced at least a gen- 

 eral sense of the major deep circula- 

 tions. And extensive theoretical de- 

 velopments over the same period have 

 given us some glimmering as to why 

 the circulations are what they appear 

 to be. 



Ocean Variability — Both the ob- 

 servational and theoretical studies 

 have dealt mostly with a steady-state 

 ocean or the long-term mean of an 

 ocean. (See Figure IV-1) During the 

 past few years, however, some data 

 have been accumulated that allow us 

 to speculate a bit about the variability 

 of the ocean. Like mean circulation, 

 variability is closely coupled to the 

 atmosphere, and variations in ocean 

 circulation may lead to, or stem from, 

 variations in atmospheric phenomena. 

 For example, one of the critical parts 



Figure IV-1 — SEA-SURFACE TEMPERATURE 



AVERAGE 



EMPERATURE 



IN C 



NORMAL 



COLD ER- 

 I I £ 



WARMER 



The figure shows sea-surface temperatures represented as deviations from global 

 average values of the sea-surface temperature. The global average value for each 

 5° latitude band is marked at the right-hand edge of the world map. Note the extent 

 of the cold equatorial water in the Pacific (from the coast of South America westward 

 halfway across the Pacific) and the warm water west and north of the United 

 Kingdom. 



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