STA.no. 153. 



70 



60 



50 



40 



30 



20 



16 



S 

 I 



u 



a 



100 ■ 



200- 



300_ 



400- 



500- 



600 



34,60 34.50 3440 34.30 34.20 



3420 



34.30 



100 



- 200 



- 300 



- 400 



- 500 



600 



Figure 19.— Vertical salinity profile along the line 153 of CalCOFI cruise 6004-B. 



the maximum and the surface water by way 

 of the isohalines of 34.80 p.p.t. (stations 7, 

 8, and 9), which was mentioned above. 



The thermal front between stations 12 and 

 14 corresponds to a salinity front which is 

 strong between stations 12 and 14 and con- 

 tinues weaker between stations 14 and 16. 

 The upwelled water present at stations 15 and 

 20 is represented by vertical isohalines corre- 

 sponding to steeply sloped isotherms (fig. 11). 

 The origin of the salinity node of about 34.70 

 p.p.t., approximately 100 m. deep at station 

 18, must be very different from that of the 

 surrounding water. Salinity profiles to the 

 north or imnnediately to the south lack water 

 of such high salinity at this depth. Because 

 salinity decreases rapidly from the center 

 of the node to the annbient water, one may 

 suppose that mixing is occurring and that the 

 salinity of the node may have been higher 

 than 34.70 p.p.t. Owing to its association 

 with isanosteres^ (260-320 cl./ton) that pass 

 through the high-salinity Gulf Surface Water, 



^ Lines of equal density. 



I tentatively suggest that the node represents 

 Gulf Surface Water. The node has a some- 

 what lower oxygen content than water to the 

 west. The high-salinity water issuing fronn 

 the Gulf near Cape San Lucas (mentioned 

 above in reference to the profile for line 153) 

 is associated with isanosteres around 240 

 cl./ton and seems a less likely cause of the 

 node at station 18. The nearest other water 

 of salinity > 34.70 p.p.t. is in the salinity 

 maximum ( Sj 130-180 cl./ton), which is an 

 even less likely source. 



The node of low-salinity water at station 16 

 is clearly due to California Current Surface 

 Water. Likewise, nodes of high-salinity water 

 at stations 12 and 10 are clearly due to Gulf 

 Surface Water. The nodes of low-salinity 

 water at station 1 1 (S < 34.60 p.p.t. at 40 m.) 

 and at station 9 (S < 34.50p.p.t., alsoat40 m.) 

 are probably due to California Current Sur- 

 face Water, especially at station 9; this water 

 influences the surface salinity at station 10 

 (see fig. 5). The node at station 9 corresponds 

 to a depression in the oxygen isopleths, sug- 

 gesting the presence of water of relatively 

 higher oxygen content. The same is true to a 



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