214 [TS]-relationship and Connection with Mixing Processes and Large Water Masses 



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Fig. 101. Standard curve of the [TSJ-relationship for the entire area of the core layer of the 

 subantarctic intermediate water in the Atlantic. 



the percentage influence of each individual component at any point in the spreading 

 area. From these percentages for all stations a chart can be made with lines of equal 

 percentages of subantarctic water to give a quantitative representation of the spread- 

 ing, the gradual mixing and the final disappearance of this type of water (Fig. 102). 

 Between 45° and 40° S. the subantarctic component of the intermediate water is still 

 about 7% ; the 50% line runs from South Africa to Cape San Roque and the 40% 

 line extends from here in a narrow tongue along the continental slope to 9° N. The 

 principal direction of spread is shown by arrows on Fig. 102. 



Wiist has investigated in a similar way the other water types important in the 

 thermo-haline structure of the Atlantic, and by making a numerical estimate of their 

 spread from the [rS'J-relations in the core layers. He thereby obtained a quantitative 

 measure of the mixing of these water types. 



A further example of the use of the [rSJ-diagram in the study of the spreading of a 

 water type is the equivalent thickness-method of Jacobsen (1943); he applied this 

 method in practice to investigate the penetration of Atlantic water through the 

 Faroes-Shetland gap into the Norwegian Sea, the northern part of the North Sea 

 and into the Barents Sea. This water type is characterized by values d' = 10-2°C 

 and S = 35-45%o. The water mass at any point in this area is formed by a mixture 

 of pure Atlantic water with other water types. If it were possible to separate pure At- 

 lantic water from the other types it would have at any point a definite thickness which 

 Jacobsen called the "equivalent thickness" of Atlantic water. At any station this 

 thickness can be found from the [rSJ-relation in the following way: Fig. 103 shows the 

 [r5]-diagram at a "Hjort" station on 1 May, 1935 at 630° N., 3-8° E. The [TS]- 

 curve approximates the observed points rather closely. 



The dashed straight line connects the points of the mixing components A (10-2°C, 

 34-5%) and P (2-5°C, 34-90%o). The distance AP is divided into ten equal intervals 

 and indicates the individual share of the two components. The section of the curve 



