Southern Oscillation Index

This figure displays a time series, in the form of vertical color bars, of the monthly standardized Southern Oscillation Index (SOI) from January 1951 to present.

Red vertical bars represent positive SOI values, and blue vertical bars represent negative SOI values. The SOI is calculated as the standardized difference between standardized Tahiti monthly average sea level pressure anomalies and standardized Darwin monthly average sea level pressure anomalies. The base period used for calculating the anomalies is January 1991 to December 2020.

Dataset Documentation

Monthly SOI data

Standardized difference of standardized Tahiti minus standardized Darwin sea level pressure anomalies
Data Source
NOAA National Centers for Environmental Prediction (NCEP) Climate Prediction Center (CPC) (Monthly Atmospheric and SST Indices: Southern Oscillation Index (SOI))
The standardized difference of standardized Tahiti sea level pressure anomalies minus standardized Darwin sea level pressure anomalies, with 1991-2020 used as the climatological base period


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