The California Current, as a matter fact, 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. Remember that in the above mentioned 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.