Jane D., Volney; John D., GRB
March 6, 2011

El Niño

Warming in the Pacific Ocean at the equator is the mark of an El Niño event.

Scientific Description

El Niño is characterized by warmer than normal temperatures in the ocean at the equator, which can have effects on the weather across the globe.
In normal conditions (see illustration below), winds from South America blow toward Southeast Asia, the air warms from exposure to the sun as it travels across the ocean, the water piles up on the east coast of Indonesia. As a result, warm temperatures at the surface of the ocean are concentrated at the equator in a smaller area near Indonesia, and the water levels are higher there as well. The relatively high temperatures in Indonesia cause conditions in the atmosphere that increase the chances of rain in this region, whereas the cooler temperatures on the west coast of South America result in drier conditions. Cooler water near the bottom of the ocean moves east and brings nutrients toward the surface off the coast of South America.
Normal conditions

During an El Niño, the winds from South America weaken or even reverse direction, which allows the warmer waters from Southeast Asia to move toward the east. This increases air temperatures above the ocean, and the nutrient-rich water no longer rises of the coast of South America. The fisherman in this region notice a decline in fish during an El Niño, and the weather patterns change in Indonesia and South America, with drought in Indonesia and Australia, and flooding in Peru in South America.
El Niño conditions

The El Niño also has impacts on the weather patterns in regions beyond Indonesia and South America, including dry conditions and draught in Australia and wet and flooding conditions in the U. S. The video below discusses El Niño and its effects.

Wordle: El Niño

Newsworthy Example

The 1997-1998 El Niño event was severe, and had an impact on weather in many areas of the world. The chart below shows the very warm temperatures that were recorded in the Pacific Ocean at the equator at this time.
The graph shows the average sea surface temperature (SST) at various points along the equator in the Pacific Ocean from 1988 to 2010 (left) and the temperature differences from normal in the same region (right). Blues are colder temperatures and red are warmer temperatures. You can see the extremely warm temperatures that occurred at the equator in the Pacific Ocean in 1997-1998.

According to a National Geographic article (http://www.nationalgeographic.com/elnino/mainpage.html), this El Niño event "deranged weather patterns around the world, killed an estimated 2,100 people, and caused at least 33 billion [U.S.] dollars in property damage." The west coast of the U.S. experienced greater than average rain fall, severe flooding, and landslides. On the other hand, this event had a positive impact in the Northeastern U.S., which experienced greater than average temperatures in the winter. There were also fewer than normal hurricanes in the mid-Atlantic states that season.

Interestingly, this was the first El Niño event in which scientists were able to predict the resulting floods and drought. The following video is a news story that aired on ABC news on August 27, 1997. It discusses the event that was, at the time, about to occur. Although forecasting El Niños has become better, some are better predicted than others.

Wordle: 1997-1998 El Niño event

Works Cited