<P> Additionally, extensive upwelling of colder sub-surface waters occurs, caused by the prevailing northwesterly winds acting through the Ekman Effect . The winds drive surface water to the right of the wind flow, that is offshore, which draws water up from below to replace it . The upwelling further cools the already cool California Current . This is the mechanism that produces California's characteristic coastal fog and cool ocean waters . As a result, ocean surf temperatures much colder along the Pacific coast than the Atlantic coast . For example, the average July SST (sea surface temperature) at New York City at 40.7 degrees latitude is 73 ° F (23 ° C), while at the same latitude in Eureka, CA is 57 ° F (14 ° C). As such, ocean surf temperatures are rarely above 66 ° F (19 ° C) during the summer along the California coast south to San Diego, while they are often above 80 ° F (27 ° C) on the east coast from North Carolina southward . </P> <P> The cold water is highly productive due to the upwelling, which brings to the surface nutrient - rich sediments, supporting large populations of whales, seabirds and important fisheries . Winds of the appropriate direction and strength to induce upwelling are more prevalent in the presence of Eastern boundary currents, such as the California Current . Phytoplankton production is dramatically increased in these areas because the nutrient - rich water lying below the pycnocline is relatively close to the surface and is thus easily upwelled . Scientists at Scripps Institution of Oceanography said in 2011 that the average surface temperature of the water at Scripps Pier has increased by almost 3 degrees since 1950 . </P> <P> The "Bakun upwelling index" is based on a 20 - year average of the monthly mean Ekman transport for different regions off the California coast . It ranges from 300 meters - cubed / second (in the offshore direction) to − 212 meters - cubed / second (toward the coast, or onshore direction). There is year - round upwelling off Southern California's coast, but it is strongest in the summer months . Off the coast of Oregon and Washington, there is forceful downwelling in the winter months, and upwelling in the region is restricted to the months of April through September . </P> <P> Primary production is a topic of interest among those who study the California Current . In their study, Hayward and Venrick (1982) found great variability in both biomass and the productivity of phytoplankton in the California Current . The differences observed by Hayward and Venrick in carbon - fixation rates (0.2--2.0 grams carbon / (meter - squared × day)) show the heterogeneous nature of the California Current, with its combination of advected (see advection) and upwelled water . Several studies have investigated the carbon flow from primary production to the pelagic fish stocks which depend on the California Current . Lasker (1988) described powerful "jets and squirts" off northern and central California . These' jets and squirts' move large quantities of cold, nutrient rich water offshore . This water then gets carried by the southward bound California Current and adds significant primary production to the sardine population . </P>

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