Figure 13. Florida Gulf Stream. Typical 

 meandering of the Gulf Stream is evident by 

 color contrast and Sargasso weed accumula- 

 tions at the Stream margins. The darker color 

 represents the warmer Gulf Stream water. 

 The photo represents the usefulness of 

 photography in differentiating some oceanic 

 features. (NASA photo) 



Recent observations have shown that the pat- 

 tern of permanent ocean currents near the Equator 

 in all the oceans is highly complex. There are 

 broad equatorial currents, flow^ing westw^ard in a 

 manner that would be expected as a response to 

 the westward component of the trade winds on 

 both sides of the Equator. But, in addition, an 

 intricate system of powerful equatorial counter- 

 currents exists at the surface and at relatively 

 shallow depths below the surface. Although var- 

 ious mathematical models have been proposed to 

 account for these current systems, at best we have 

 only approximate steady state models. 



Attack on the problems of predicting fluctua- 

 tions in major ocean currents will require both 

 an extensive series of field observations to describe 

 their actual behavior in nature and research in 

 geophysical fluid dynamics to account for the 

 observed properties of the currents in terms of the 

 inputs of thermal and wind energy on a rotating 

 earth. 



Extensive efforts, both observational and 

 theoretical, have been carried out in recent years 

 by various government agencies and private scien- 

 tific institutions. The ability to mount meaningful 

 observational programs in the ocean as well as to 

 develop theoretical models has increased markedly 

 in recent years. There have been substantial 

 international collaborative efforts to study ocean 

 current systems such as the International Coopera- 

 tive Investigation of the Tropical Atlantic and the 



Cooperative Study of the Kuroshio and Adjacent 

 Regions.^^ These efforts should be intensified; the 

 time has come to marshal the Nation's scientific 

 and technological capabilities to plan comprehen- 

 sive attacks on outstanding problems of ocean 

 circulation dynamics, both in the field and in the 

 laboratory. 



Recommendation: 



The Nation should undertake a series of systematic 

 investigations into the oceans' current systems to 

 study their dynamics through cooperative field 

 investigations, marshalling at one time multiple 

 ship, buoy, and aircraft arrays, as well as an 

 expanded effort in the theoretical and mathe- 

 matical modelling of such systems. 



C. Scales of Motion 



Superimposed on the great river-like flow pat- 

 terns of oceanic circulation and tending to obscure 

 their details whenever observations are closely 

 spaced, either in distance or in time, is a complex 

 pattern of smaller scale motions. Some of this 

 motion is associated with internal waves on inter- 

 faces between layers of differing density. Some of 

 it takes the form of eddies and gyres with 

 dimensions ranging from meters to hundreds of 

 kilometers. Such motion appears to be responsible 

 for most mixing in the sea.^ ^ 



Studies of the characteristics of these motions 

 have revealed that appreciable energy is involved, 

 whatever the frequency or scale investigated. 

 Further investigation of these motions, by direct 

 observation, by operation of hydraulic models, 

 and by computer simulation, is needed to account 

 in detail for the mechanisms by which they are 

 produced and by which energy is transmitted from 

 one type to another. 



This problem is fundamental, not only to the 

 ability to understand oceanic processes in order to 

 begin to simulate these processes mathematically 

 as well as in the laboratory, but to determine the 

 nature of the sampling intervals required for ocean 



Established by Intergovernmental Oceanographic 

 Commission Resolutions 11-7 and 1II-5 respectively. 



Organized Convection in the Ocean Surface Layer 

 Resulting from Slides and Wave Radiation Stress, Kraus, 

 Physics of Fluids, Vol. 10, No. 9, pt. 2, 1967. 



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