Oceanographic Setting

The productive ecosystem off the coast of California has three oceanographic seasons: upwelling season in the spring and early summer, relaxation in the late summer and fall, and the storm season in winter.


upwelling season

Upwelling Season:

During the upwelling season (March-July), strong northwest winds and the south flowing California Current combine with the earth's rotation to drive surface waters away from the shore. These surface waters are replaced by an upwelling of nutrient-rich deeper water from offshore. The nutrients become available for surface dwelling phytoplankton (microscopic marine algae). Phytoplankton form the foundation of this oceanic food web and the combination of nutrients and increased sunlight in spring initiates a bloom of life that radiates up the food web. An abundance of phytoplankton, zooplankton, and young fish are food for animals at higher levels of the marine food web.


relaxation season

Relaxation Season/Oceanic Period:

During the late summer and fall (August to early November), coastal winds weaken and the sea surface becomes calmer. Surface currents during this time period are mostly northward and water temperatures increase. During this time, coastal waters are rich with the products of upwelling, and many migratory animals are in the area feeding on an abundance of prey.


winter storm season

Winter Storm Season/Davidson Current Period:

The winter storm season (mid-November through February) is dominated by rough seas and greater mixing of ocean water. Strong winter storms originating in the Gulf of Alaska cause turbulent conditions that mix the stratified ocean layers in the upper water column. This results in similar temperature, salinity, and concentration of nutrients throughout the water column.


For more information on oceanography within Cordell Bank Sanctuary and the research being conducted on this topic, please visit the Sanctuary Integrated Monitoring Network (SIMoN).