Southern Oscillation Index (SOI)

The data are here.

The Southern Oscillation Index (SOI) is the difference between the standardized Tahiti Sea Level Pressure (SLP) and the standardized Darwin SLP measurements. They are provided by the CAC climate bulletin:

This is an important index for measuring ENSO.

The climate bulletin runs from 1951 through the present.

We also have the standardized SOI from 1881-present here. The earlier data was furnished by Judy Cole.