El Nino Explained

[yojimbo]

Always hear about El Nino, but never understand what really causes it. This passage describes the causes very simply and clearly:

The pulses of warmer water moving across the ocean are Kelvin waves. Sea level is naturally higher in the western Pacific; in fact, it is roughly 40 to 50 centimeters (15-20 inches) higher near Indonesia than off of Ecuador. Much of this difference is due to tropical trade winds, which predominantly blow from east to west across the Pacific Ocean, piling up the water near Asia and Oceania. When those trade winds ease and bursts of wind come out of the west, warm water from the western Pacific sloshes east in vast and deep waves and evens out sea level a bit. As the warm water piles up in the east, it suppresses the natural upwelling that usually keeps waters cooler along the Pacific coasts of the Americas.
The seas and skies have been doing just that in 2015. According to observations compiled by the National Oceanic and Atmospheric Administration (NOAA), at least three sizable west wind bursts have occurred in the Pacific since March, and each came shortly before a Kelvin wave rolled across the basin. Those waves have raised water temperatures in the central and eastern Pacific by as much as 1.6 degrees Celsius (2.9° Fahrenheit) above normal, making for a “strong” El Niño. The warmers waters off the west coast of the Americas have led to warmer and more humid weather ashore, as well as soaking bursts of rain. At the same time, Indonesia and other parts of the western Pacific have been unusually dry.

Taken from this article: http://earthobservatory.nasa.gov/IOTD/view.php?id=86341

[drroc]

That's pretty crazy that the wind can raise up so much water volume.

[knyfe]

Oh and thats why the water is so warm THIS year ;-)