(Aka El Nino Southern Oscillation)
An irregular oscillation of the Pacific ocean's climate system. It is linked to high sea-surface temperatures off Peru's coast — i.e. El Nino coupled with a change in the atmospheric pressure regime (the Southern Oscillation)
The ENSO song
Two irregularly oscillating southern women sing a paen to the atmospheric pressure regime.
Example Usages -
1. "Likewise, in a 2006 test of reliability, William Merryfield used 15 GCMs to predict future El Niño-Southern Oscillations (ENSO) in a green- house-warmed climate, and found that, “Under CO2 doubling, 8 of the 15 models exhibit ENSO amplitude changes that significantly (p<0.1) exceed centennial time scale variability within the respective control runs. However, in five of these models the amplitude decreases whereas in three it increases; hence there is no consensus as to the sign of change.”
So of 15 GCMs, seven predicted no significant change, 5 predicted a weaker ENSO, and 3 predicted a stronger ENSO. This result is exactly equivalent to ‘don’t know.’ The 15 GCMs tested by Merryfield were the same ones used by the IPCC to produce its Fourth Assessment Report"
(Source: A Climate of Belief by Patrick Frank )