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 source: NOAA | THE WRATH OF EL NIÑO October 3, 1997 |
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Return to this forum's introduction.
Questions answered in this forum:Where does El Niño get its energy? Will this El Niño be the biggest in 150 years? How does the NWS model El Niño? Does El Niño have any positive effects? What factors determine the frequency of El Niño? Who will suffer the most from El Niño?
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Outside Links
The National Weather Service's Climate Prediction Center page on El Niño.
Joseph Lanza of Marietta, GA, asks: How does the Weather Service model the effects of the El Niño? Does the Weather Service use Chaos theory when modeling the El Niño? Can the Weather service predict when the El Niño will start or stop?
Dr. Robert E. Livezey of the National Weather Service responds:
Dear Mr. Lanza,
The effects of El Niño are modeled through the use of both physical and statistical models. The physical approach utilizes the massive computer model of the global atmosphere used by the National Centers for Environmental Prediction for climate prediction. It is fed the forecasts of global sea surface temperatures which embody the El Niño forecast and we note how this input alters weather patterns.
The other approach, statistical modelling, has been very productive as well. By judicious selection of past cases, we can build up a picture of the probabilities of different weather conditions when a strong El Niño is in progress. A rich catalog of insight into El Niño's North American as well as global impacts has been built up in this way over the last decade. Linear statistical models are used as well. Both of the approaches implicitly recognize and include the implications of chaos theory.
Satisfactory demonstrations do now exist that a number of physical and statistical models, including several at the National Weather Service's Climate Prediction Center (CPC), do have some skill in predicting changes in El Niño out to as much as nine months to a year in advance. Naturally, this skill decreases from the shorter lead times to quite modest levels a year in advance. Things like exact timing, rapidity of change, etc. will be handled less and less skillfully with longer lead times. Nevertheless, clues that an El Niño would be underway this Fall were provided by the better models almost one year ago.
What are the positive effects of El Niño?
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