Coastal Upwelling Along the Northern California Current

Coastal upwelling brings cold, nutrient-rich water from the deep ocean to the sunlit surface layers fueling phytoplankton growth and providing the base for productive coastal ecosystems. Coastal upwelling regions typically occur on the eastern side of oceanic basins and are often areas with very productive fisheries. Significant upwelling areas around the world are off the west coast of the United States (California Current), Peru/Chile (Humboldt Current), Portugal/NW Africa (Canary Current), and SW Africa (Benguela Current).

Coastal upwelling can be caused by winds as a result of a phenomena known as Ekman transport – as wind blows parallel to the coast, surface waters move to the right of (i.e., perpendicular to) the wind. In the case of the Oregon coast, southward blowing winds create upwelling-favorable conditions, where surface water flows to the right of the wind away from the shore. When these conditions occur, deep water then rises, or upwells, to the surface to replace the water moving offshore.

In this OOI Nugget, data from a coastal glider on the OOI Coastal Endurance Array captures upwelling as it flies through the water column in its sawtooth diving pattern from offshore, up the continental slope, and onto the continental shelf. The event captured by the glider transect is put into a broader perspective by examining the shelf surface mooring wind and water temperature data.