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MEASUREMENTS OF THE OCEANIC CIRCULATION 

 IN TEMPERATE AND TROPICAL LATITUDES* 



William S. von Arx 



OCEANIC CIRCULATION 



At the present time the circulation of the oceans in temperate and tropi- 

 cal latitudes presents at least two rather separate aspects for study; the wind- 

 driven system extending perhaps to the depth of the main thermocline, and a 

 deep circulation system in which secondary effects of the wind-driven system 

 and thermohaline effects may both be significant. 



The wind-driven system has received the bulk of recent observational 

 and theoretical study. In this work observers are equipped to make only frag- 

 mentary measurements of transient occurrences, while theoretical effort has 

 been concerned mainly with the steady state, wind-driven circulation. It is dif- 

 ficult to reconcile these two kinds of results, Midway between them is the 

 transient state which both groups hope to describe sooner or later. 



Since physical intuition is acknowledged as an unsafe basis for the theo- 

 retical description of the oceans, it is necessary at first to describe transient 

 conditions from observations. This description must be based mainly on direct 

 observations taken sinnultaneously over a sufficiently large area to have synoptic 

 meaning, and for a long enough time to distinguish the longer periodic variations 

 from secular trends. It should be acceptable, at first, to average out the 

 sinaller scale turbulent processes so that only the bolder features of the flow 

 pattern are revealed. Even so, this is a more ambitious program of observa- 

 tions than can be managed at present. 



It seems evident that rather than new instruments we require new meth- 

 ods of observation which are adapted to the scale of the field problem. These 

 methods should possess elements of speed and penetration to depths which far 

 surpass those attainable from moving ships or aircraft for we would like to ob- 

 serve what is happening simultaneously at many places in the ocean and continue 

 such observations for some time. Fixed ocean stations might be desirable. 

 These might be designed either to record events against time, or report them 

 at intervals. 



In that the fine structure of the oceans cannot be inferred by interpola- 

 tion, it also seems desirable to increase the density and simultaneity of obser- 

 vations from ships. This might be done by providing measuring devices which 

 drift with the water to establish the continuity of the ocean structures between 



* - Contribution No. 689 from the Woods Hole Oceanographic Institution. 



