Salinity distribution 



Figure 13 shows the distribution of surface salinity contoured at 

 o ^ 



0, 1 /oo intervals. As in the case of the surface temperature distribu- 

 tion, there were no outstanding features. Relatively large salinity gra- 

 dients were encountered east of Hawaii and between 159°W. and 160°W. 

 along the southwest edge of the survey region. A tongue of high salinity 

 water extended south toward and through Kauai Channel until south of 

 Kauai it turned west. 



Table 2 shows that the average salinity increased from east to 

 west on each side of the island chain, with extremes of approximately 

 34.4 /oo and 35.3 /oo. Considering the whole cruise area, the salin- 

 ity increased on the average from south to north, reaching a maximunn 

 at approximately 26 N. , and then decreased towards 29 N. South of 

 26 N. the salinity increased from east to west whereas north of this 

 latitude it decreased. 



Density distribution 



Figure 14 shows the surface density (sigma-t) distribution with 

 contour intervals of 0. 1. Both north and south of the islands the density, 

 on the average, increases toward the west, and when figures 13 and 14 

 are connpared, other similarities between the isopleths of salinity and 

 sigma-t become apparent. Some of these are the relatively large gra- 

 dients east of Hawaii, between 159 W. and l60 W. at the southern edge 

 of the survey region, and high and low salinities south of Kauai and in 

 the vicinity of station 49 which correspond with pockets of high and low 

 sigma-t values, respectively. Thus, south of the island chain the salin- 

 ity materially influences the surface density distribution, becoming less 

 important on the windward side until north of 24 N. the temperature plays 

 a dominant role. 



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It was noted above that at 26 N. the salinity and temperature show 



changes in trend. These are also reflected in the surface density distri- 

 bution (fig. 14), suggesting that 26 N. may be the southern boundary of a 

 region generally referred to as the subtropical convergence. (See p. 15, 

 Subsurface Circulation. ) 



Surface circulation 



Figure 15 shows the surface circulation represented by the dynamic 

 topography relative to 1,000 m. The survey region is dominated by a num- 

 ber of vortices, some cyclonic, others anticyclonic (counterclockwise, 

 clockwise), centered in the vicinity of stations 49, 39, 1, and 23. The 



13 



