El Niño is a climate pattern that describes the unusual warming of surface waters in the eastern tropical Pacific Ocean.
- El Nino is the “warm phase” of a larger phenomenon called the El Nino-Southern Oscillation (ENSO).
- El Niño and La Niña are considered the ocean part of ENSO, while the Southern Oscillation is its atmospheric changes.
- La Nina, the “cool phase” of ENSO, is a pattern that describes the unusual cooling of the region’s surface waters.
How El Niño get Initiated?
- Change in surface water of eastern tropical Pacific Ocean is intimately tied to the atmosphere and to the winds blowing over the vast Pacific.
- Easterly trade winds (which blow from the Americas toward Asia) loose strength and momentum and can even turn around into westerlies.
- This allows great masses of warm water to slosh from the western Pacific toward the Americas.
- It reduces the upwelling of cooler, nutrient-rich waters from the deep—shutting down or reversing ocean currents along the equator and along the west coast of South and Central America.
- The circulation of the air above the tropical Pacific Ocean responds to this tremendous redistribution of ocean heat.
- The strong high-pressure systems of the eastern Pacific weaken, thus changing the balance of atmospheric pressure across the eastern, central, and western Pacific.
- The vastness of the Pacific basin—covering one-third of the planet—these wind and humidity changes get transmitted around the world, disrupting circulation patterns such as jet streams (strong upper-level winds).
- These large-scale shifts in Pacific winds and waters initiate El Niño.
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Effects of El Niño:Primary effects: These effects are directly caused.
- Alteration of weather patterns which include:
- Temperature changes
- Precipitation changes
- Storm track changes and intensity
- Alteration of currents and ocean temperature
Secondary effects: These are some consequences.
- Crash of fisheries
- Plagues (hanta virus)
- Insect population explosion leading to disease and plagues.
- Crop failure
Benefits of El Niño:
- Fewer hurricanes and other tropical cyclones in the north Atlantic
- Milder winters in southern Canada and the northern continental United States.
- Replenishment of water supplies in the southwestern U.S.
- Less disease in some areas due to drier weather (like malaria in southeastern Africa)
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