California Current

The California Current is the cold eastern boundary current of the North Pacific, flowing equatorward along western North America as the eastern limb of the North Pacific subtropical gyre. Spring and summer equatorward winds drive offshore Ekman transport and coastal upwelling, raising cold, nutrient-rich water that sustains a productive fishery. The broad, slow surface flow carries low-salinity subarctic water southward, while the poleward California Undercurrent runs along the slope beneath it. The system shows strong interannual variability tied to ENSO and the Pacific Decadal Oscillation.