The California Current is a Pacific Ocean current that moves southward along the western coast of North America, beginning off southern British Columbia and ending off southern Baja California Peninsula. It is one of five major coastal currents affiliated with upwelling zones, the others being the Humboldt Current, the Canary Current, the Benguela Current, and the Somali Current.The California Current, is the continuation of the Aleutian Current. The term “the California Current” is given to this branch of the Aleutian Current between 48°N and 23°N lat.
This cold current is similar to the Peru and Canaries Cold Currents. The northeast trade winds carry large amount of surface water from the coast of California and pile it up along the western part of the ocean. Thus, the water level near the coast is lowered.
The California Current compensates the loss of water along the California Coast. In this latitudinal belt the mixing of sub-arctic water mass and the equatorial water mass takes place.
In summer, from March till the end of July water from the deeper layers of the ocean comes up at the surface. Thus, there is upwelling of cold and dense water from the bottom of the ocean.
From these areas of upwelling the cold water with very low temperature extends towards the south along the sea coast in belts. However, according to Sverdrup and Fleming, cold water up-wells only from a depth of 200 meters.
The main areas of upwelling of cold water lie at 35° and 41°N latitudes. In the summer months a counter current originates at a depth of 200 meters below the surface which carries enormous quantity of equatorial water towards the north. By the end of the northern summer numerous eddies form near the coast which carry the coastal water away from the coast.
During winter, when the upwelling of cold intermediate water stops, a counter current starts flowing between the California Current and the coast. It is called the Davidson Current.
The temperature and salinity of its waters vary with seasonal variations in upwelling, insolation, and flow. The maximum ranges in temperature and salinity from its northern to its southern end are 9° to 26° C and 32.5 to 34.5 parts per thousand, respectively. During the summer, when upwelling is most dominant, a countercurrent below 650 ft develops close to the coast. The cold upwelling water brings rich nutrients to the surface and abundant plankton and animal life is supported.
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