Parameter Tree:
EARTH SCIENCE > CLIMATE INDICATORS > ATMOSPHERIC/OCEAN INDICATORS > SEA SURFACE TEMPERATURE INDICES > EXTREME EASTERN TROPICAL PACIFIC SST

Definition:
The Niño1+2 SST anomaly index is an indicator of far eastern tropical Pacific El Niño conditions, off the coasts of Peru and Chile. It is calculated with SSTs in the box 90°W - 80°W, 10°S - 0°.

Reference:
Ocean Observations Panel for Climate (OOPC):
http://ioc3.unesco.org/oopc/state_of_the_ocean/sur/pac/nino1+2.php