Gulf of California — Roden 
39 
The mean annual surface temperature is 
quite high in the Gulf and lies around 24°C 
(Table 4). In Mazatlan the mean annual tem- 
perature is very high (26.0) and the surface 
water there is probably of advective origin, 
because it is always warmer than the air above 
it (Fig. 5). 
Mean monthly salinities (USCGS 1951) are 
listed in Table 4. The salinity (Fig. 15) has 
two maxima and two minima. The first maxi- 
mum is found around June and is the result 
of excessive evaporation. With the coming 
of the rainy season the salinity of the surface 
water falls and reaches a minimum at the peak 
of the rainy season. In October increasing 
winds and rapidly decreasing air temperatures 
and the lack of large precipitation give rise 
to a second peak in net evaporation which is 
also reflected in the second salinity maximum. 
After the October maximum the salinity de- 
MONTH 
XII I II III IV V VI VII VIII IX X XI XII 
Fig. 15. Net evaporation and salinity for Guaymas, La Paz, and Mazatlan. 
