California Current
The California Current (
The related California Current Conservation Complex is a grouping of federally-designated marine protected areas that have been on the UNESCO list of tentative World Heritage Sites since 2017, which includes the following areas found throughout the current: the Point Reyes National Seashore, the Golden Gate National Recreation Area, the Monterey Bay, Greater Farallones and Cordell Bank National Marine Sanctuaries, the Farallon Islands National Wildlife Refuge, and the California Coastal National Monument.[1][2]
Physical properties
The movement of Alaskan and northern ocean currents southward down the west coast results in much cooler ocean temperatures than at comparable latitudes on the east coast of the United States, where ocean currents come from the Caribbean and tropical Atlantic. The cooler ocean current along the west coast also makes summer temperatures cooler on the west coast compared to the east coast. For example, Half Moon Bay at 37°N has no month with an average high above 67 °F (19 °C) and San Francisco often stays below 70 °F (21 °C) in summer, while Virginia Beach, VA, close to the same latitude, has high temperatures above 80 °F (27 °C) in summer.
Additionally, extensive
The cold water is highly productive due to the
The "Bakun upwelling index" is based on a 20-year average of the monthly mean Ekman transport for different regions off the California coast since the 1970s. 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.[5] Other measures have also been proposed for this important seawater system, although some rely on shorter data series. For example, using data series available since 1988, the Coastal Upwelling Transport Index and the Biologically Effective Upwelling Transport Index provide improved estimates of vertical transport and vertical nitrate flux.[6]
Measurements relevant to this current have only been made with instruments since 1946. Prior to this date, the processes, and especially the nutrient status of waters, have to be inferred from historic data sources. One example are the nitrogen isotope ratios in macroalgae.[7] California current is a very wide, cold and strong current. It runs southward down North America.
Biological properties
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.[3]
Related currents
A narrower, weaker counter current, the
Within the
In popular culture
In the 2016
References
- ^ Centre, UNESCO World Heritage. "California Current Conservation Complex". UNESCO World Heritage Centre. Retrieved 2023-04-13.
- ^ Schmalz, David. "Monterey Bay nominated to be UNESCO World Heritage site". Monterey County Weekly. Retrieved 2023-04-13.
- ^ ISBN 9781405111188.
- ^ Lee, Mike (June 18, 2011). "Is global warming changing California Current?". U-T (San Diego Union Tribune). Retrieved June 20, 2011.
- ^ Bakun, Andrew (1973). Coastal Upwelling Indices, West Coast of North America, 1946–71. National Marine Fisheries Service.
- S2CID 62777184.
- PMID 32546101.
- Carina Stanton. Warmer oceans may be killing West Coast marine life. Seattle Times. 13 July 2005. Retrieved 22 March 2008.
- Schwing, M.R., Mendelssohn, R., Bograd, S.J. 2003. El Nino Impacts of the California Current Ecosystem. Report produced by NOAA Fisheries, Southwest Fisheries Science Center. 1–8.