24°- 

 N. 



22' 



20' 



MEXICO 



MAZATLAN 



114 °W. 



112° 



110° 



108° 



106° 



Figure 15.— Thermocllne topography In the entrance to the Gulf of California and off western Lower California during 

 cruises TO-60-1 and 6004-B, respectively. The contour interval is 10 m. 



Salinity 



Figures 16, 17, 18, and 19 show the profiles 

 for station lines 143, 147, 150, and 153, re- 

 spectively, off western lower California. In 

 all of them the surface salinity generally in- 

 creases westwards. The salinity minimum, 

 typical of California Current Surface Water is 

 present; it tends to increase in salinity with 

 decreasing latitudes and agrees in depth with 

 the thermocline (figs. 6, 7, 8, and 9). The 

 maximum that marks Subtropical Subsurface 

 Water (now being modified at these latitudes) 

 is represented by nodes of water of about 

 34.70 p.p.t., the extent of which increases 

 with decreasing latitude. The deep minimum 

 of Intermediate Water is not fully revealed in 

 these profiles. Upwelling tends to produce 

 relatively high inshore salinities and a slight 

 surface minimum offshore. 



A further unusual feature is the subsidiary 

 salinity minimum at 150 m. at station 153.60. 

 This apparent parcel of water shows on the 

 corresponding temperature profile (fig. 9) as a 

 dome in the 12° C. isotherm and on the corre- 

 sponding oxygen profile (fig. 26); it probably 



originated in the California Current Surface 

 Water. The high salinity at 50 m. at station 

 153.16 is undoubtedly due to an intrusion of 

 Gulf Surface Water. As is seen here and later, 

 the isohalines, 34.70 and 34.80 p.p.t., of this 

 Gulf Surface Water often join with the same 

 isohalines of the salinity maximum of the 

 Subtropical Subsurface Water, and traverse 

 a wide range of density surfaces in so doing. 

 The profile along line 153 also shows less 

 upwelling inshore than do the profiles to the 

 north. 



Along the line of stations 1 to 5 (fig. 20), in 

 the innermost part of the Gulf entrance, the 

 salinity merely increases with depth to the 

 deep minimum of the Intermediate Water at 

 roughly 800 m. The profile between stations 

 7 and 22 (fig. 21) depicts a complicated 

 salinity distribution. Although one cannot be 

 dogmatic in ascribing various parts of the 

 profile to various water types, the deep 

 salinity minimum (400-1,000 m.) and the 

 salinity maximum, now represented partly by 

 isohalines of 34.80 p.p.t., remain as definite 

 structures ascribable to Intermediate. Water 

 and Subtropical Subsurface Water, respec- 

 tively. There is also the connection between 



18 



