420 



SALINITY (%o) 

 60 80 34.00 .20 40 .60 80 35.00 .20 40 .60 80 36.00 20 



I i f~n r 



21 (W) 



1^20^26,30 



140 



WARM SIDE •- 



COOL SIDE — -^ 



197a i 200 



± 



Figure 35.— T-S curves (on a-p field) for the two hydrocasts (2.1 on warm (w) side, 2.2 

 on cool (c) side) at front 2. Numbers against curves indicate depths. 



The water on the cool side has characteristics 

 of California Current water (cool, with low 

 salinity) at the surface, but its salinity rapidly 

 increases with depth (unlike California Current 

 water). The result is an altogether anomalous 

 T-S curve, but below about 90 m. it conforms 

 to either equatorial Pacific or Gulf water 

 (figs. 7 and 8). There is a relatively small 

 density difference between the two sides of 

 this front at the surface (about 15 cl.ton"!) but 

 at depths down to .about 70 m. the density dif- 

 ferences are greater than those found at front 

 5 (p. 24), 



There was a strong vertical gradient of 

 dissolved oxygen and of phosphate (PO4-P) 

 at about 70 m. depth, agreeing more or less 

 with the thermocline. 



The catches of one oblique 1-m. net haul 

 on either side of front 2 afford no information 

 about the effect of this front on the zooplankton 



distribution. The compositions of the two 

 catches differ markedly (table 5). 



Front 4 



This front was located very near the posi- 

 tion of front 2 (fig. 1), but 13 days later. 

 Because the temperatures on either side and 

 the difference between them were similar to 

 those at front 2, and because the two fronts 

 were at the same place, it was expected that 

 they would have similar properties, but in 

 general they do not. 



Among the common forms, chaetognaths (not 

 significantly) and euphausiids are relatively 

 more abundant on the cool side than on the 

 warm; siphonophores (only the more or less 

 solitary sea bells were found) are somewhat, 

 but not significantly, less numerous on the 

 cool side. Note the five exclusive groups 



46 



