Walker circulation

The Walker circulation is the large-scale east-west overturning circulation over the tropical Pacific. Under typical conditions, warm water and deep convection dominate the western Pacific, while subsidence and cooler conditions prevail farther east.

Climatic role

This circulation is tied to the trade winds, the east-west slope of the thermocline, and the strength of the Pacific Equatorial Undercurrent. It therefore helps connect basin-scale Pacific variability to local ocean and atmosphere conditions.

ENSO connection

During El Nino, the Walker circulation weakens and the zonal temperature gradient relaxes. During La Nina, it strengthens. These shifts alter tropical convection, ocean upwelling, and rainfall patterns across the Pacific, including in the Galapagos.

See also: El Nino-Southern Oscillation, Thermocline, Sea surface temperature