Kauai Channel is the only channel for which there are sufficient data to 

 attempt to contour the topography. The resulting flow pattern is very confused. 

 The heights of the surfaces at station 8 indicate northerly or cloclcwise flow around 

 the west coast of Gahu. On the Kauai side of the channel northerly flow is in- 

 dicated by the 0-, 50-, and 100-decibar surfaces and westerly by the 200-declbar 

 surface. 



Temperatures 



The temperature data are again based on the bathy thermograms. Figure 14 

 shows the temperature profiles for the five sections indicated on the track chart. 

 Figure 15 is a plot of the depth of the 75°F. isotherm, which was drawn as an 

 example of a rapid field method for obtaining the major features of the circulation 

 pattern. 



ever most of the area the basic configurations of the temperature field 

 followed the pattern expected from the geostrophic flow. For example, both the 

 cross sections and the plot of the dep*-,h of the 75^. isotherm show a doming of the 

 subsurface isotherms at stations 10 and 23. 



The temperature field in Kauai ChaLnel differed in some respects from 

 that expected from the geostrophic currents. At station 3, where the isotherms 

 dome, there was mixing, caused by divergence or wind stirring, strong enough to 

 lower the surface temperature. The plot of the 75°F. isotherm indicates that it 

 was part of a cold dome extending northeastward to the area between stations 6 and 

 7. The cyclonic circulation required to produce this condition agrees with the 

 northerly geostrophic currents at the surface on the Gahu side of the channel but 

 not with those on the Kauai side. 



As a result of summer heating, the temperature of the surface layers in 

 the area west of Hawaii were at least 1° to 2°r. higher than those of cruise 1. 

 The effects of local heating are shown in the cross sections by the small cells of 

 water at the surface having a temperature higher than 79°F. 



31gffla-t 



The effect of summer heating on the density is shown on the cross sec- 

 tions by the lower density of the approximate boundary between the quasi-homogeneous 

 surface layer and the well-defined density gradient. At the time of the winter 

 cruise (cruise 1) the boundary was the 23.8 surface, but on this cruise it was only 

 the 23.2 surface. 



In the surface layers (fig. 17), two features stand out in the complicated 

 circulation pattern. The first is the band of surface water with sigma-t greater 

 than 23.0 on the northeast side of the islands. It was not related to the current 

 pattern but was a combination of the high salinity around station 31 and the low 

 temperatures along the islands (bucket and reversing thermometer temperatures). 

 The second was the low values, as low as 22. b5 which occurred over the surface of 

 the eddy west of Hawaii. They were due to high surface temperatures which per- 

 sisted in spite of the force 5 winds reported in the bathythermograph log. 



The horizontal plots of depth of sigma-t surfaces (fig. 18) have the topo- 

 graphy indicated by the geostrophic currents. They are included only for the detail 

 they add in the area north of the middle group of islands. The 25. and 26.0 con- 

 tours show that the incident currents separated north of Molokai, one branch turning 

 northwest along the islands, and the other turning cyclonically away from the is- 

 lands, thus completing the pattern shown by the geostrophic currents. 



12 



