34 
PACIFIC SCIENCE, Vol XII, January, 1958 
water extends over a depth range of 50 m. 
and inflowing over 1500 m., across latitude 
23°N, the velocity of the outflowing water 
is 7 cm/sec and of the inflowing water 0.3 
cm/sec. This calculation holds only for win- 
ter, when northerly winds are responsible for 
outflow at the surface. 
The influence of the Gulf of California 
upon the adjacent Pacific Ocean is small 
(Sverdrup et al ., 1942: 732) and varies with 
season. The influence is greatest in winter 
when strong northerly winds drive the surface 
layers out of the Gulf and least in summer 
when southerly winds drive oceanic water into 
the Gulf. The exact distance seaward from the 
entrance of the Gulf that Gulf water can be 
detected (by its higher salinity) is not known. 
The circulation in the vicinity of the Gulf 
of California is affected by the water carried 
south by the California Current and by the 
water found off Mexico and Central America. 
The former is characterized by a low tempera- 
ture, a low salinity, and a rather high oxygen 
content, whereas the latter has a very high 
temperature at the surface and a very low 
oxygen content below the thermocline (Sver- 
drup et al ., 1942: 730). Between both lies a 
transition region which, 500 miles to the 
west, is found approximately between lati- 
tudes 17°N and 20°N (Wooster and Crom- 
well, verbal communication). 
In February (Fig. 10) the coastal surface 
circulation (U. S. Hydrog. Off., 1947) is 
characterized by southward currents north of 
about latitude 20°N and by westward flowing 
currents south of this latitude. An interesting 
feature is a large gyre off the southern coast 
of Mexico which is maintained by strong 
