HYDROLOGY OF THE BRANSFIELD STRAIT 



43 



Then, if we allow the relative heights for November 1929 to remain, we can use the 

 value WS 478 = 7-37, which was obtained in Table IV, column 5, in the above relation 

 between St. WS 478 and St. 543. Thus we obtain St. 543 = 0-12 relative to the 

 November 1929 values. As we have already obtained relative values for December 1930 

 (Table V) this new value (St. 543 = 0-12) can be substituted in these values, so that in 

 Table VI we have a direct comparison between November 1929 and December 1930. 



Table V 



It only remains to link the line of stations from Snow Island to Trinity Island taken 

 in December 1930 with the line of November 1929 from Livingston Island to Trinity 

 Peninsula. This was done by a direct comparison of the dynamic depths to the 1300 

 decibar surface of Sts. 550 and WS 483 as follows: 



St. 550-WS 483 = 3-53 dynamic cm.; 

 but in Table IV, column 5, we have WS 483-WS 480 = 7-95 dynamic cm. By addition, 

 therefore, St. 550-WS 480 = 1 1-48 dynamic cm. Thus we have now a complete relative 

 relationship for the level of the sea surface for the majority of the stations in November 

 1929 and December 1930 above that at St. WS 480. These figures are given in Table VI 

 below. 



The values in Table VI were entered on a chart of the area and dynamic isobaths were 

 drawn at intervals of every dynamic centimetre. In the construction of the isobaths 

 attention was paid to the law of Ekman which states the change of direction of flow 

 of a convection or gradient current when approaching shallowing or deepening water. 

 In the southern hemisphere a gradient current will turn to the left on approaching a 

 shallower part of the ocean and to the right when approaching deeper water. Topo- 

 graphical charts for surfaces other than that of the sea surface were made on the basis 

 of the above table by using the differences of dynamic depth to these surfaces of the 

 various stations and the basic station WS 480. In this way topographic charts for the 

 levels of o, 50, 100, 200, 300, 400 and 600 m. were constructed and are given in 

 Figs. 52-8. On account of the fact that observations from two different years have been 

 used in these charts, it is not strictly accurate to represent the dynamic isobaths as 

 continuous lines. Consequently the junction of the November and the December 



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