>Long-Term ONI-Like Table Of El Niño and La Niña Events

>The following tables were prepared to provide a reference of El Niño and La Niña events since 1900, using HADISST-based SST anomalies for the NINO3.4 region. They are based on the same definition of warm and cool ENSO events that NOAA uses for its Oceanic NINO Index (ONI). That is, all data are first smoothed with a 3-month running-average filter. An El Niño event is highlighted in red and identified with an “EN” in the far-right column if the 3-month average of NINO3.4 SST anomalies remained equal to or above 0.5 deg C for 5 consecutive 3-month periods. Likewise, a La Niña event is represented by blue and identified with a “LN” if the 3-month average of NINO3.4 SST anomalies remained equal to or below -0.5 deg C for 5 consecutive 3-month periods. And the same base years were used as the ONI Index, 1971 to 2000.

Since ENSO events typically peak in boreal winter, the second to last column reflects the two years of event evolution and decay. ENSO events typically develop during one year and decay the next—except, obviously, when an El Niño or La Niña event spans multiple years. The response of global temperatures lags the tropical Pacific and would typically be seen in the year of the decay. The same thing holds true for La Niña events. The two-year designation in the table should help avoid the confusion over an “El Niño year” or a “La Niña year” because it identifies the evolution and decay years.

Due to the length of the table, I had to break it into two parts.
###########################

http://i56.tinypic.com/i3850k.jpg
Long-Term ONI-Like Table Of El Niño and La Niña Events – 1900 to 1949
################################
http://i56.tinypic.com/npmbkg.jpg
Long-Term ONI-Like Table Of El Niño and La Niña Events – 1950 to 2010

The table allows for quick comparisons. Example:

Global sea surface temperature anomalies rose from 1910 to 1944, dropped from 1945 to 1975, and rose again from 1976 to present. Keying off the development year, during the period from 1910 to 1944, there were 10 El Niño events and 6 La Niña events. (For this simple comparison, if an El Niño or La Niña event extends from one winter to the next, it would be considered two events.) From 1945 to 1975, there were only 7 El Niño events, compared to 11 La Niña events. And from 1976 to present, El Niño events dominated again. There were 12 El Niño events but only 8 La Niña events.

NOTES

The tables have been formatted similar to the ONI Index, but that doesn’t mean one should subscribe to the notion that global temperatures only respond to the 3-month average of NINO3.4 SST anomalies if they are beyond the threshold used in the tables.

SOURCE

HADISST NINO3.4 SST anomalies are available through the KNMI Climate Explorer Monthly climate indices webpage.