Diagram showing the principle of the El Niño in the central Pacific. Colors indicate temperature, with red being warmest and blue coldest. In normal, non-El Niño conditions (top panel of schematic diagram), the trade winds
blow towards the west across the tropical Pacific. These winds pile up warm surface water in the west Pacific, so that the sea surface is about 1/2meter
higher at Indonesia than at Ecuador. During El Niño (bottom panel of the schematic diagram), the trade winds relax in the central and western Pacific leading to a depression of the thermocline
in the eastern Pacific, and an elevation of the thermocline in the west, thereby bringing an end to nutrient upwelling
. (From: NOAA).
For more information on El Niño go to:
Scripps Institution of Oceanography