Niño 3 is the departure from the 19

Niño 3 is the departure from the 1971-2000 mean of
the SST averaged over the 5°N-5°S, 150°W-90°W
region, where a large variability of the SST
associated with ENSO takes place. Since the early
1980s this region has been considered as a reference
for the strength of the ENSO episodes. Niño 3 index
used in this study was obtained from the website of
NOAA’s Climate Prediction Centre
(http://www.cpc.ncep.noaa.gov/data/indices/).