The California Current: A Cold, Southward-Flowing Giant

Direction and Dynamics

The California Current flows **southward** along the western coast of North America, from southern British Columbia to the southern tip of the Baja California Peninsula.

Driving Forces

• Wind-Driven (Ekman Transport): Prevailing northwesterly winds (driven by the North Pacific High) push surface water offshore (to the right in NH). This upwells cold, nutrient-rich water from depth.
• Eastern Boundary Current: It's the eastern limb of the **North Pacific Subtropical Gyre** (clockwise circulation).

Key Characteristics

• Cold: Sea surface temps 5–10°C cooler than same-latitude western Pacific.
• Upwelling: Intense spring/summer upwelling fuels one of the world's most productive marine ecosystems (fisheries, kelp forests, marine mammals).
• Seasonal Variability: Strongest upwelling April–September; Davidson Current (northward countercurrent) appears inshore in winter.
• Width: 500–1,000 km offshore.

Climate & Ecological Impact

• Coastal fog & cool summers (San Francisco).
• Supports major fisheries (sardine, anchovy, salmon, Dungeness crab).
• Vulnerable to El Niño (weakens upwelling) and climate change (intensified stratification, acidification).