Definitions for "Southern Oscillation Index"
Keywords:  tahiti, darwin, soi, enso, oscillation
This is calculated from the monthly or seasonal fluctuations in the air pressure difference between Tahiti and Darwin. Sustained negative values of the SOI often indicate El Niño episodes. Positive values of the SOI are associated with stronger Pacific trade winds and warmer sea temperatures to the north of Australia, popularly known as a La Niña episode ( BoM 2002).
The Southern Oscillation Index (SOI) is calculated from the monthly or seasonal fluctuations in the air pressure difference between Tahiti and Darwin. Click here for more information
( SOI) is the difference between the seasonally normalized sea level pressures of Darwin, Australia and Tahiti. A negative SOI (also called "low index") usually relates to a weakening of the Trade Winds and a resulting warm event. Conversely a positive SOI ("high index") usually relates to an increase in the Trades and a resulting cool event. [ Table, Plot