Walker Circulation

The Walker circulation is the zonal atmospheric overturning over the tropical Pacific, with rising air and deep convection over the warm western Pacific warm pool, eastward flow aloft, sinking over the cool eastern Pacific, and a low-level easterly trade-wind return at the surface. It is maintained by the east-west sea-surface temperature gradient that the trade winds themselves sustain through Bjerknes feedback. During El Nino the gradient weakens and the cell slackens and shifts east; during La Nina it strengthens. The Walker cell links tropical Pacific ocean dynamics to global climate teleconnections.