El Nino
Several years ago, a large portion of the globe was experiencing exceptional weather patterns. Meteorologists and climatologists attributed it to the El Nino factor. That prompted many laymen to wonder ‘what is El Nino?’. It is the a somewhat periodic climate pattern in the area of the eastern tropic regions of the Pacific Ocean. It occurs every three to seven years. It is characterised by warming of the surface of the ocean. The opposite effect is La Nina that is characterized by the cooling of the surface of the same region.
The exact cause of El Niño events are still unknown, but they begin when trade winds falter for several months. A series of relatively warm subsurface waves of water that are a few centimeters high and hundreds of kilometers wide(Kelvin waves)cross the Pacific along the equator and create a pool of warm water near South America where the water is normally cool. The weakening of the winds can also create another sign of a future El Niño, twin cyclones. The Pacific Ocean is a heat reservoir and it drives global wind patterns. The change in its temperature will alter weather across the globe. Rainfall shifts toward the Americas and Indonesia and India become drier. The Madden-Julian oscillation may also speed the development and intensity of El Nino.
El Nino has several components. The Southern Oscillation is the atmospheric component of El Niño. This is an oscillation in surface air pressure over the tropical eastern and the western Pacific Ocean. Its strength is measured by the Southern Oscillation Index (SOI). The SOI is computed by fluctuations in the surface air pressure between Tahiti and Darwin, Australia. Negative SOI values characterize El Niño.
El Nino affects different parts of the globe in different ways. South America sees increased rainfall, North America sees major changes in snowfall and precipitation amounts, East Africa gets more rainfall while southern and central Africa see drier conditions as do Australia and Asia. Europe does not see any measurable changes.
The changes in rainfall and ocean temperature impact many industries around the world. The harshest effects are seen in the fishing industry. While many enjoy the climate changes, fishermen face the loss of their businesses and livelihoods.
We have written many articles about El Nino for Universe Today. Here’s an article about the warmest world in 12000, and here’s an article about El Nino causing hurricanes.
If you’d like more info on El Nino, check out NASA’s Climate Change page. And here’s a link to NASA’s Earth Observatory.
We’ve also recorded an episode of Astronomy Cast all about planet Earth. Listen here, Episode 51: Earth.
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