PART IV — DYNAMICS OF THE ATMOSPHERE-OCEAN SYSTEM 



complicated and that the primary 

 problem is to make more profound 

 our understanding of the ocean as a 

 hydrodynamical phenomenon. 



What We Know — and Don't Know 



It has been pointed out that there 

 has been a really effective growth of 

 understanding of ocean surface waves 

 only in the last decade. And ocean 

 surface waves are probably the most 

 easily observable and dynamically 

 linear of ocean phenomena. Internal 

 waves and oceanic turbulence are not 

 so easily observable, and treatments 

 of these phenomena are a thin tissue 

 of preliminary theory largely unsup- 

 ported by observation. Studies limited 

 to rather high-frequency phenomena 

 actually represent the kind most 

 nearly duplicable in the laboratory. 



There is a small body of theory 

 concerning oceanic circulation, but it 

 deals only with the climatological 

 mean circulation. The role of medium- 

 scale eddy processes in ocean circula- 

 tion is completely unknown, although 

 current measurements indicate that 

 they can be very important — as, for 

 example, they are in the general circu- 

 lation of the atmosphere. A two- 

 pronged development of mathematical 

 modeling and fairly elaborate field in- 

 vestigation is going to be necessary to 

 develop much further our under- 

 standing of the hydrodynamical in- 

 teraction of these eddies and the 

 mean circulation. (A working group 

 of the Scientific Committee on Ocean 

 Research of the International Coun- 

 cil of Scientific Unions recommended 

 a "Mid-Ocean Dynamics Experiment" 

 (MODE).) Considering the three- 

 dimensional detail of velocity struc- 

 ture and its development in time that 

 such a measurement program will 

 entail, it seems clear that a major 

 input from the engineering commu- 

 nity will be needed.) 



Technological Limitations 



Oceanography is not presently 

 competent technologically to tackle 



the tasks of measurement that are 

 necessary in trying to tinravel the 

 dynamical features of large-scale mo- 

 tions. The difficulty is simply that one 

 needs to map variables like velocity 

 rather densely in large volumes (per- 

 haps 2 miles deep and 300 miles on a 

 horizontal side) for rather long pe- 

 riods (perhaps a year) with sufficient 

 accuracy that reliable statistics can be 

 calculated for complicated functions 

 like triple correlation products. Many 

 different modes of motion are occur- 

 ring simultaneously, and we need to 

 be able to separate one mode from 

 another in order to compute interac- 

 tions. Therefore, a great variety of 

 arrays of sensors need to be arranged 

 in different configurations and on 

 different scales for gathering the kind 

 of data required from the ocean. 

 Some test portions of the ocean will 

 need to be heavily instrumented in a 

 manner more sophisticated than pres- 

 ent small-scale observational opera- 

 tions can achieve. It is safe to say 

 that solutions of problems of internal 

 waves, the general circulation and 

 eddy processes, and such important 

 local processes as coastal upwelling 

 are simply going to have to wait until 

 major new instrumental arrays be- 

 come available. 



There is a limit beyond which in- 

 ferior technique cannot go. It needs 

 to be made very clear what a helpless 

 feeling it is to be on a slow-moving 

 ship, with a few traditional measuring 

 techniques like water bottles and 

 pingers on hand, trying to keep track 

 of a variable phenomenon like an 

 eddy that won't hold its shape. A 

 faint idea of the elusiveness of the 

 phenomenon can be conveyed to any- 

 one who has tried to pick up mercury 

 with his fingers or who has watched 

 a teacher trying to keep track of her 

 pupils on an outing to a public park. 

 But the ocean environment is so much 

 larger, so much harder to see, that we 

 don't bring many of "our children" 

 home. Measurement in large-scale 

 ocean physics illustrates this limit 

 very well. Further theoretical devel- 

 opment is simply going to have to 

 wait upon adequate measurement 



technique. The theoretical difficulties 

 are not serious; mathematical model- 

 ing can be worked by machine once 

 sufficient insight has been gained as 

 to what is actually going on in the 

 ocean. 



The Need for Mathematical Models 



Some advances in climate control, 

 pollution evaluation, and numerical 

 weather forecasting might be achieved 

 simply by extending present land- 

 based meteorological networks into 

 the ocean by means of buoys. Per- 

 haps a superficial knowledge of tem- 

 perature on a coarse grid in the upper 

 100 meters of the ocean will be useful 

 to meteorologists. But this will not 

 provide the basis for a quantitative, 

 rational, ocean-prediction system. 



In order to be able to predict the 

 mechanism of the ocean it is neces- 

 sary to have numerical-mathematical 

 models that have been verified by 

 comparison with actually observed 

 case histories of oceanic motion. Be- 

 cause there are several modes of such 

 motion, these experiments or com- 

 parisons have to be made on several 

 different scales. But to date they have 

 not been made. They are beyond our 

 technical means. 



Actually, it is too early to try to 

 design an oceanic monitoring system; 

 some experimental measuring systems 

 are needed first — aimed squarely at 

 providing input for mathematical 

 numerical modeling of the basic hy- 

 drodynamical processes at work. Suc- 

 cessfully tested models could evolve 

 into successful prediction schemes. 

 If sufficient resources were mus- 

 tered to start a good crew of instru- 

 ment engineers on a sample program 

 of measurement, sufficient progress 

 might be made in carrying out one 

 sample comparison of theory and 

 observation to catalyze progress on 

 the other necessary experiments. One 

 has the feeling that the science is 

 locked in a dead-center position, and 

 that a mighty shove is going to be 

 needed to get it rolling. 



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