Chapter 12 



ON THE TAGGING OF WATER MASSES FOR THE STUDY OF PHYSICAL 



PROCESSES IN THE OCEANS^ 



Theodore R. Folsom, Scripps Institution of Oceanography, La Jolla, California 



and 

 Allyn C. Vine, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts 



Finding, identifying, and plotting the courses 

 of characteristic masses of water in the oceans 

 are major activities of the physical ocea- 

 nographer. Assistance from the new techniques 

 that have come with the use of radioactive 

 materials has been welcomed by him; some of 

 these techniques have already been put into 

 service for tracing the water. It is not gen- 

 erally realized how much experience has been 

 gained, beginning with the 1946 tests in Bi- 

 kini Lagoon, in tracing water masses contam- 

 inated with radioactive materials from weapons' 

 tests. And many thoughts are now turning 

 toward the radioactive tagging of ocean water 

 by other means in regions where knowledge of 

 underlying physical processes are meager, espe- 

 cially in the very deep waters. Proposals for 

 the disposal in the sea of atomic energy wastes 

 cannot be properly evaluated until estimates 

 can be improved concerning the motion of this 

 deep water. 



Many of the advantages (familiar in the 

 laboratory) of using radioactive identifying tags 

 can be realized at sea, even though rendered 

 difficult by the very large physical dimensions 

 of the oceans. What appeals most to the ocea- 

 nographer is his new ability, under certain cir- 

 cumstances, to make very rapid identifications 

 of water lying on the surface or deep below his 

 ship; thus allowing large volumes to be sur- 

 veyed in three dimensions and in more detail 

 than ever before possible. 



Three layers in the ocean are distinguished 



1 Contribution from the Scripps Institution of 

 Oceanography, New Series, No. 905. 



Contribution No. 929 from Woods Hole Oceano- 

 graphic Institution. Part of Table 2 was computed 

 with the collaboration of John Harley of AEC, New 

 York City Operations Office, who gave much other 

 counsel for which the authors are grateful. 



clearly by structure and behavior: the mixed 

 layer near the surface; the intermediate layer 

 lying just below wherein the temperature changes 

 rapidly with depth (this thermal stratification 

 bringing about great stability) ; and finally, the 

 large, nearly uniform bottom water mass ex- 

 tending to the sea floor with so little variation 

 in density that very stable stratification is not 

 possible. Each water mass reacts differently 

 when disturbed, and therefore, mixing occurs 

 differently in response to currents and mass 

 intrusions. Experiments conducted in any one 

 of these domains must take into consideration 

 the special features that exist, and must call 

 upon equipment most suited to these sections. 

 Equipment specialized for radiological survey 

 work in any of these oceanographic domains is 

 still primitive. However, it can be said that 

 equipment for detecting and measuring radia- 

 tion is not a bit less highly developed than are 

 the equipment and techniques needed for navi- 

 gating a ship, and for maneuvering detectors 

 at sea, especially at great depth. So much in- 

 formation now can be reported by radiological 

 means in a short time that a ship now has more 

 reason than heretofore for precise navigation. 

 In some cases, the depth and position of the 

 detector relative to the ship must be known 

 instantly, and almost always must be controlled 

 far better than has been accepted by traditional 

 hydrography. It is difficult to record data in 

 full detail in many cases, and in others it is 

 difficult to evaluate features rapidly enough to 

 alter maneuvers to best advantage; an ocea- 

 nographer can now expect to be aware of a 

 strongly active layer in less than one second 

 after his electronic probe makes contact, and 

 he even may make use of a fast moving airplane 

 to outline radioactive areas on the surface. 



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