El Niño Southern Oscillation
El Niño and La Niña are extreme phases of a naturally occuring climate cycle referred to as El Niño-Southern Oscillation or the ENSO cycle.
The ENSO cycle is part of a complex set of interactions that couple the surface of the ocean and the atmosphere in the tropical Pacific. Changes in the ocean impact the atmosphere and influence climate patterns around the globe. In turn, these changes in the atmosphere impact the ocean temperatures and currents. The system oscillates between warm (El Niño), neutral, and cold (La Niña) conditions over an irregular interval that averages 3 to 4 years. El Niño and La Niña can cause floods in some areas and droughts in others. For an animation (800KB) of changing ocean temperatures during the 1997-1998 El Niño, click here or on the image.
For more information regarding ENSO patterns or to learn more about El Niño and La Niña and how they will affect climate near you please visit the following sites: