El Niño Impact on Walker Circulation

El Niño is characterized by the unusual warming of surface waters in the central and eastern tropical Pacific Ocean.

The Walker circulation is a normal, large-scale atmospheric circulation across the equatorial Pacific. In its typical state, it involves easterly trade winds moving surface air westward, causing air to rise in the western Pacific (near Indonesia and Australia) and sink in the eastern Pacific (near South America). This creates a pressure gradient between the west and east Pacific.

During an El Niño event, the sea surface temperatures in the central Pacific warm significantly. This warming disrupts the normal pressure gradients and weakens the easterly trade winds. Consequently, the Walker circulation weakens or becomes "dampened." The rising and sinking air patterns shift, leading to changes in precipitation and temperature across the Pacific basin and potentially influencing global weather patterns.

Hadley, Ferrell, and Polar circulations are distinct atmospheric circulation systems operating at different latitudes and are not the primary systems directly dampened by El Niño's specific impact on the equatorial Pacific.

Therefore, El Niño over the central Pacific region leads to the dampening of the Walker circulation.