SECT. 3 J 



EASTERN BOUNDARY CURRENTS 



257 



(Munk, 1950). This theory suggests that, on the eastern sides of oceans, the 

 character of the circulation depends on the vorticity of the meridional winds, 

 the balance being between wind stress vorticity and planetary vorticity, with 

 lateral stress vorticity playing a minor part. 



Accordingly, the eastern boundary currents are slow, broad and shallow with 

 relatively small transport, in contrast to the intensified western currents which 

 are narrow and swift, extend to great depths and transport vast quantities of 

 water. 



1 60° 140° 120" I0O 



160° 140° 120° 100° 80° 



(a) 



20° 0° 20° 40J 



(b) 



Fig. 3. Surface geostrophic circulation (dynamic height anomalies, over 1000 db). 

 (Pacific after Reid, 1961 ; Atlantic adapted from Defant, 1941, Teil. XIV.) 



The direction of flow is evident from charts of surface drift (Fig. 2) and the 

 surface dynamic topography (Fig. 3). Direct current measurements are scarce, 

 but available GEK measurements (e.g. Fig. 4) support the picture of equator- 

 ward flow. However, it is more satisfactory to speak of a prevailing equatorward 

 component, since both the direct measurements and the dynamic charts 

 indicate the presence of numerous eddies and other irregularities of flow. 



