96 



surface since this is the reference surface used in the construction of 

 the dynamic topographic chart shown. Because of the wide spacing 

 of the stations, details of circulation cannot be derived from either 

 part of figure 27. However, this much is regarded as certain: That 

 the axis of minimum temperature is well defined and the southward 

 flow clearly indicated. There is a choice open as to whether the axis 

 passes east or west of the central station at the north end of the 

 diagram. In the isentropic analysis the axis has been shown as 

 passing east of this central station in order to preserve the simplest 

 diagram. In the dynamic chart the axis seems to pass to the west 

 of this central station. The main point is that the two circulation 

 pictures are in general agreement.^ 



In considering surfaces of equal density such as in an isentropic 

 analysis one of the steps involved is the plotting of lines of equal 

 (Xi on temperature-salinity coordinates. It has been found useful 

 to work with two open-scale curves. In the first curve temperature 

 is plotted against D for the value of ai being considered, where D is 

 defined by the equation ao=(Tt-\-D. For the construction of such a 

 curve table 2 gives appropriate values for whole degrees of tempera- 

 ture from —2° to 15° C. and for various values of at covering the 

 range usually encountered in the Ice Patrol area, derived by interpo- 

 lation from page 46 of Knudsen's Hydrographical Tables. 



In the second curve cto is plotted against salinity. For facility in 

 plotting such a curve Knudsen's formulae relating chlorinity and ag 

 and cldorinity and salinity have been combined to give the following 

 relationship between salinity and ao, where S represents salinity in 

 parts per thousand: 



5 For further details see Soule, Floyd M. Consideration of the Depth of the Motionless Surface Near 

 the Grand Banks of Newfoundland. Jour. Marine Res., vol. H, No. 3, pp 169-380. New Haven. Janu- 

 ary 17, 1940. 



