98 



Linear Theories — Viscous 



The shape of the X curve for the western current shown in fig. 61 may be 

 compared with the transport function ijr computed geostrophically from 

 hydrographic data for both the Gulf Stream and Kuroshio (fig. 62). The 

 east- west scale of the theoretical curves depends upon the particular choice 

 of k involved, hence of lateral-eddy viscosity. In order to produce a Gulf 



100 



200 



300 km. 



Fig. 62. The mass-transport stream function i/r computed from oceanographic 

 data across the Kuroshio and Gulf Stream. Compare these with the left-hand 

 side of fig. 61. From Munk (1950, fig. 4). 



Stream 200 km. wide, Munk chooses ^ =5 x 10' cm.^/sec. A smaller value 

 of A would give a narrower Gulf Stream. 



The more recent cross sections of the Gulf Stream (e.g., fig. 33) suggest 

 that the width of the main current used by Munk is three or four times as 

 great as it should be. Thus, for a purely frictional theory the coefficient of 

 lateral-eddy viscosity must be reduced to about 10® cm.^/sec. Although this 

 adjustment of the parameter A is perfectly admissible, there being no in- 

 dependent measure at present, the inertial terms are no longer negligible, 



