The seasonal and interannual variability of the California Current system: A numerical model

A reduced gravity model that incorporates the geometry of western North America has been used to study the dynamics of the California Current system. Three experiments were performed: first the model was run using 19 years of wind stress from the Comprehensive Ocean‐Atmosphere Data Set (local model); a second experiment (remote model) consisted of forcing the model through its southern boundary using the results of a similar reduced gravity equatorial model; in a third experiment, both forcings were used simultaneously (local plus remote model). The main objective of this work was to analyze the low‐frequency variability on the California Current system in terms of its contributions from remote and local forcing. Away from the coast, the basic (steady) state of the model is determined by the predominantly negative wind curl through a Sverdrup balance. The general seasonal cycle is in agreement with what has been described by other authors. Through cross‐correlation and cross‐spectral analysis between the model results and observed sea level data, it was established that most of the interannual variability in sea level height at the coast is due to disturbances of equatorial origin that propagate into the region in the form of coastally trapped Kelvin waves. For the annual frequency variability, on the other hand, it was found that both local and remotely forced variability contribute to the total variance.