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National Oceanic and Atmospheric Administration The Top 10 El Niño Events
of the 20th Century
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Climate Perspectives Branch, Global Climate Lab
National Climatic Data Center, Asheville, NC
June 4, 1998
Global temperature anomalies during the ten strongest El Niños of the Twentieth Century are shown above. The width of the bar represents the character of the event. El Niño events have a duration varying between half a year to a year and a half. Over recent years, El Niño events have become more frequent as the global temperature anomalies associated with each El Niño continue to increase. This means that the extreme regional weather and climate anomalies associated with El Niño are being exacerbated by increasingly higher temperatures. The warmer conditions have been linked to higher concentrations of atmospheric greenhouse gases.
El Niño events were based on work described in: Livezey et al., 1997: Teleconnective response of the Pacific-North American region atmosphere to large central equatorial Pacific SST anomalies, J. Climate, 10, 1787-1819.
 Land Data Anomalies
Year.mid deg.C deg.F duration
in months
1915.08 0.017 0.031 11.0
1918.00 -0.012 -0.022 8.0
1941.55 0.141 0.253 15.0
1958.12 0.278 0.500 9.0
1966.00 -0.007 -0.013 8.0
1973.00 0.237 0.426 6.0
1983.05 0.393 0.707 7.0
1987.12 0.337 0.606 6.0
1992.08 0.526 0.947 10.0
1997.75 0.835 1.502 13.0
Ocean Data Anomalies
Year.mid deg.C deg.F duration
in months
1915.08 -0.051 -0.092 11.0
1918.00 -0.100 -0.180 8.0
1941.55 0.177 0.319 15.0
1958.12 0.212 0.382 9.0
1966.00 0.071 0.127 8.0
1973.00 0.229 0.412 6.0
1983.05 0.333 0.599 7.0
1987.12 0.220 0.397 6.0
1992.08 0.255 0.458 10.0
1997.75 0.523 0.942 13.0
Land and Ocean Data Combined into an Anomaly Index
Year.mid deg.C deg.F duration
in months
1915.08 -0.031 -0.055 11.0
1918.00 -0.074 -0.133 8.0
1941.55 0.166 0.299 15.0
1958.12 0.232 0.417 9.0
1966.00 0.047 0.085 8.0
1973.00 0.231 0.416 6.0
1983.05 0.351 0.632 7.0
1987.12 0.255 0.459 6.0
1992.08 0.336 0.605 10.0
1997.75 0.617 1.110 13.0
The average annual temperature of the globe is about 59 deg. F (15 deg. C). That value can be added to global anomalies to approximate absolute temperatures. Anomalies (also called departures from average) are used because they describe more accurately climatic variability over large areas than the absolute temperatures do and they give a frame of reference that allows for easier interpretation of the numbers. For example, a summer month over a large area may be cooler than average, both at a mountain top and in a nearby valley, but the absolute temperatures may be quite different at the two locations. The use of anomalies in this case will show that temperatures for both locations were below average. For these reasons, it is the anomalies that are computed for large-area summaries (like a hemisphere or the globe), not the temperature itself.
An analogy using human body temperatures might help to explain why anomalies are useful. The "average" human body temperature is about 98.6 deg. F. But some people have lower normal temperatures than others. For someone with a normal body temperature of 98.0 deg. F., a temperature reading of 98.6 deg. would indicate a fever. The use of 98.6 deg. alone would not indicate this condition to most people but the use of an anomaly or departure from the normal body temperature for this person (+0.6 deg. F) would indicate the feverish condition.
For further information on the El Niño Events, contact:
Mike Crowe
NOAA/National Climatic Data Center
151 Patton Avenue
Asheville, NC 28801-5001
fax: 828-271-4328
email: michael.crowe@noaa.gov
- or -
Thomas Peterson
NOAA/National Climatic Data Center
151 Patton Avenue
Asheville, NC 28801-5001
fax: 828-271-4328
email: thomas.c.peterson@noaa.gov
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Last Updated Thursday, 17-Feb-2005 07:21:45 EST by Catherine.S.Godfrey@noaa.gov
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