24" 



N. 



22' 



20' 



MEXICO 



MAZATLAN 



.95- 



1.00 



SAN BENEDICTO I 



II4''W. 



II2° 



110° 



108° 



106° 



Figure 35. — Horizontal distribution of the dynamic height anomaly at the sea surface over the 500-decibar surface (solid 

 lines) for part of CalCOFI cruise 6004-B and for cruise TO-60-1, and over the 1,000-decibar surface (broken lines) 

 for cruise TO-60-1 only. Arrowheads show direction of flow; the speed of flow in this and the next figure can be judged 

 by using the graph in figure 34. The contour interval is 0.05 dynamic meter. 



Surface currents 



As noted by Reid (1958), GEK (Geomagneto- 

 ElectroKinetograph) measurements are in- 

 stantaneous and may depart from average 

 conditions because of tidal effects. It is not 

 surprising therefore that the results of GEK 

 measurements show only an indifferent agree- 

 ment with geostrophic flow. Figure 37 shows 

 the surface currents measured by GEK on 

 TO-60-1. The currents are represented vec- 

 torially; velocities in centimeters per second 

 are given next to each arrow. The four closely 

 grouped measurements south of Cape Falso 

 were made at Front 1 near station 15 (Grif- 

 fiths, 1965). 



Dissolved oxygen 



The horizontal distribution of dissolved 

 oxygen at the sea surface (fig. 38) differs 

 markedly from the distributions of other 

 properties so far mentioned. No frontal system 

 is obvious. The water off western Lower 

 California is all undersaturated (80 - 90 per- 

 cent), presumably owing to recent upwelling 

 as indicated by the isopleths. In contrast, 

 water around stations 12 to 16 is oversaturated 

 (>110 percent), as is the water south and 

 west of the Tres Marias Islands. This over- 

 saturation indicates prolonged contact with 

 the atmosphere or considerable agitation at 

 the sea surface. The water around Mazatlan 



40 



