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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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Oliver Katcher of New York, New York, asks: The size of El niño seems to fluctuate from year to year, are there any expectations that the frequency may change. It has clearly grown in size, will that or any other variable effect how often it appears? If it does appear more frequently does that reflect an increase in the global mean ocean temp or is it simply colder elsewhere in the ocean? Thank you very much.
Dr. Robert E. Livezey of the National Weather Service responds:
Dear Mr. Katcher,
Actually, the size of El Niño doesn't really change much from episode to episode but its strength does and that's what matters. As I've already suggested in previous responses its cycle is also very irregular. For instance, there were a number of very strong El Niños between 1900 and 1920, a few in the early 1940s, and several per decade from the late 1950s to the present, but only very weak ones in the periods in between. The last decade and a half has been a particularly active period for strong El Niños.
While El Niños are often accompanied by pools of cooler than normal waters in the western equatorial Pacific and at higher latitudes north and south of the equator, the net effect on the average temperature of the global oceans is positive, i.e. a net warming. Because this is the case and because the 1980s and 1990s have been dominated by strong El Ninos with only one major La Nina during the period, the problem of detecting global warming (if it is underway) has been considerably complicated. This is because some analyses, including one of my own, have suggested that some of the features of the global warming oceanic signature resemble El Niño. So picking these two things apart in the records is tricky, although some success has been achieved so far. Global warming's impact on El Niño itself is not clear either because recent work has suggested that there are feedback effects in the tropics that offset some of the warming at the equator. What we need to address these questions is a coupled global atmosphere-ocean model that can reproduce the current climate well, including the ups and downs of El Niño and La Niña.
Who's hurt the most by El Niño?
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