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.

Variation in sea surface temperature typically parallels changes in wind velocity along the north-south axis. As the wind shifts southward, sea surface temperatures tend to decrease indicating upwelling is bringing cold deep waters to the surface. The grey highlighted area denotes the time period when the glider made its trek from offshore back up the continental slope and onto the shelf.

Glider temperature and chlorophyll data. As the glider moves to the east, closer to shore, sea surface temperature cools indicating mixing with deep, upwelled water. In these areas closer to the coast, chlorophyll concentrations increase as phytoplankton growth is likely fueled by upwelled nutrients.

Access the Data

Disclaimer: data used in this example and provided in the .csv file were downloaded from the OOI on November 12, 2019. The file format and/or contents could have changed if downloaded directly from OOI Net after this date.

Access from OOI Net:

Pull Data Using Python Code. Code demonstrates how to download CTD and fluorometer data from an Endurance glider, and Bulk Meteorology data from an Endurance surface mooring using the Machine-to-Machine (M2M) interface, remove outliers, calculate depth-binned hourly averages, and export the data as a .csv file. We also demonstrate how to make a map of a glider track.

Plot Glider Data Using Matlab Code. Code demonstrates how to graph glider data from a .csv file.

Data Review Pages:
Bulk Meteorology Instrument Package
3-Wavelength Fluorometer

Endurance Array Coastal Glider 320 (CE05MOAS-GL320)

Location: On this deployment, the glider (320) conducted an east-west transect from approximated 20-m isobaths to 128°W along a latitude of 44.63°N off the coast of Newport, OR. Map denotes the glider’s track colored by time for the portion of the deployment plotted above. The X markers indicate the locations of the Endurance array moorings.
Lat/Lon: 44.63°N, 124.6-127.95°W
Water Column Depth: Samples down to 1000m
Platform: Coastal Glider
3-Wavelength Fluorometer (FLORT-M) – in glider science bay
CTD (CTDGV-M) – in glider science bay

Endurance Array Oregon Shelf Surface Mooring (CE02SHSM)

Location: On the Continental Shelf off the coast of Oregon in the NE Pacific
Lat/Lon: 44.6393°N, 124.304°W
Water Column Depth: 80 m
Platform: Surface Buoy
Instruments: Bulk Meteorology Instrument Package (METBK-A) – attached to buoy tower 3m above sea surface

Essentials of Oceanography Textbook Sections

7.2 What creates ocean surface currents and how are they organized?
7.3 What causes upwelling and downwelling?
7.4 What are the main surface circulation patterns in each ocean basin?
10.6 What are the characteristics and types of coastal waters?
13.1 What is primary productivity? What are the margins of the ocean so rich in life?
16.4 What changes are occurring in the oceans as a result of global warming?

For more details, check out the full “Textbook Crosswalk”

Next Gen Science Standard Connections

HS-LS2-5. Develop a model to illustrate the role of photosynthesis and cellular respiration in the cycling of carbon among the biosphere, atmosphere, hydrosphere, and geosphere. These data provide one component of this broader model by highlighting productivity generated along the coast due to upwelling.

Additional Resources

NOAA National Ocean Service – What is upwelling?
National Geographic Encyclopedic Entry – Upwelling

OOI Science Theme

Ocean Circulation, Mixing, and Ecosystems

Related Publications

Barth, J.A., et al. 2018. Warm blobs, low-oxygen events, and an eclipse: The Ocean Observatories Initiative Endurance Array captures them all. Oceanography 31(1):90–97.

Henderikx Freitas, F., et al. 2018. Temporal and spatial dynamics of physical and biological properties along the Endurance Array of the California Current ecosystem. Oceanography 31(1):80–89.

Xiu, P., et al. 2018. Future changes in coastal upwelling ecosystems with global warming: The case of the California Current System. Scientific Reports 8:2866.

Smith, R.L. 1974. A description of current, wind, and sea level variations during coastal upwelling off the Oregon coast, July–August 1972. Journal of Geophysical Research 79(3):435-443.