PART IV — DYNAMICS OF THE ATMOSPHERE-OCEAN SYSTEM 



of the heat engine is the Norwegian 

 Sea, an area where warm saline sur- 

 face water from the Gulf Stream is 

 cooled by contact with the atmos- 

 phere, made dense, and returned to 

 the open Atlantic as dense deep water 

 in such quantity as to create a recog- 

 nizable subsurface layer extending 

 throughout the Atlantic, Antarctic, 

 Indian, and Pacific oceans. In this 

 case, the power to drive this thermo- 

 haline engine comes from heat ex- 

 change with the atmosphere. 



Warming of the surface waters in 

 low latitudes and cooling in high lati- 

 tudes creates easily recognizable ef- 

 fects on the circulation of the ocean. 

 The effect of this exchange on the 

 atmosphere is equally important, not 

 just locally — in that the coast of 

 Norway remains ice-free — but also 

 in the larger sense of general effects 

 on the world atmospheric climate. 

 The budget of this heat exchange and 

 the details of its various expenditures 

 must be learned if the earth's climate 

 is to be understood. Seasonal and 

 nonseasonal variations of the heat 

 exchange, and their causes and ef- 

 fects, must be studied. 



The Gulf Stream is both a cause 

 and an effect of this exchange. It 

 would exist in any case as a conse- 

 quence of the wind-driven circulation 

 in the trade-wind and westerlies areas, 

 as do, in a weaker form, its South 

 Atlantic, North Pacific, and South 

 Pacific counterparts. (The heat and 

 water sink of the far North Atlantic 

 requires a vaster flow in the Gulf 

 Stream than in the other western 

 boundary currents.) But variations in 

 the strength of the Gulf Stream may 

 be either causes or consequences of 

 variations in heat exchange in the 

 Norwegian Sea. Although the effects 

 of these variations may be severely 

 damped by the time the waters enter 

 the immense reservoir of the abyssal 

 ocean, there is no certainty that their 

 effects on the far reaches of the ocean 

 are negligible. 



Some of the most interesting varia- 

 tions yet observed in the ocean are 



in the North Pacific, where bodies of 

 surface water thousands of miles in 

 diameter remain warmer or colder 

 than their seasonal means for periods 

 ranging from three months to over a 

 year. Such features seem to be char- 

 acteristic of the North Pacific. Thus, 

 a typical map of surface temperature 

 is not one that is very near the norm 

 everywhere, with many small highs 

 and lows; instead, the whole North 

 Pacific may consist of three to five 

 large areas of deviant temperature. 

 Such features have been noted only 

 in the past fifteen years. They are 

 beginning to receive the attention of 

 meteorologists, as well as oceanogra- 

 phers, since their consequences for 

 the atmospheric climate cannot be 

 discounted in attempting to under- 

 stand and predict the world's weather. 



Prediction — Our present under- 

 standing of the ocean is barely suffi- 

 cient to account for the major cir- 

 culations in a general way. Some 

 preliminary attempts are now being 

 made to predict specific features of 

 ocean behavior, most of them being 

 based on the persistence of deviations 

 from the mean. That is, if an area 

 shows an abnormally high surface 

 temperature in one month, this anom- 

 aly is apt to endure or persist for 

 several months more and to diminish 

 to the norm slowly. Strictly speaking, 

 this is not prediction but merely the 

 extrapolation of a present feature. 

 More ambitious predictions are being 

 contemplated, but they are still in 

 very early stages. 



Advances in Instrumentation 



Devices to measure ocean currents 

 have improved greatly over the past 

 ten years. They have been used to 

 monitor changes in position of the 

 Gulf Stream, to measure its deep 

 flow, and to investigate some of the 

 principal inferences about deep cir- 

 culation in the Pacific and Atlantic 

 oceans. Considerable improvement 

 has also been achieved in instruments 

 for measuring water characteristics. 



Moored buoys of various kinds 

 have been developed for deep-water 

 use within the past decade. They are 

 used for monitoring certain character- 

 istics of the ocean and atmosphere, 

 including wind, air, and sea tempera- 

 ture, subsurface temperature, waves, 

 and, possibly, water velocity. These 

 measurements can either be recorded 

 and recovered by vessels or trans- 

 mitted immediately by radio to ap- 

 propriate shore bases. 



The future may see interrogation 

 and retransmission of signals by satel- 

 lite. The advantages of such monitor- 

 ing stations would include relatively 

 inexpensive operation (compared to 

 weather ships) and the ability to 

 gather data from regions that are out- 

 side normal shipping lanes but may 

 be extremely pertinent to ocean and 

 weather studies. 



Deficiencies in the Data Base 



The data base for study of the 

 ocean consists of measurements of 

 water characteristics in various loca- 

 tions and depths at different times 

 and measurements of currents, waves, 

 tides, and ocean depths. In some 

 areas and some seasons, this data 

 base is adequate for a long-term mean 

 to be established; it is not continuous 

 enough in time, however, to allow for 

 adequate study of variations from the 

 long-term mean. In other areas and 

 seasons, the data base barely exists. 

 High-latitude areas in winter have 

 hardly been explored. Our knowl- 

 edge of the deep arctic is extremely 

 limited. Some few winter data are 

 available from the antarctic region. 

 The deeper parts of the ocean may be 

 better represented in the present data 

 base than the surface parts, since the 

 deeper parts show less time-variation 

 than the upper layers. 



Other parts of the data base in- 

 volved in investigating ocean circu- 

 lation include atmospheric-pressure 

 observations and wind measurements, 

 air temperature and the like. These, 



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