Indices soi standardized sea level pressure difference
Important Note:As of 2100 UTC on 27 Aug 2012, the SOI data in this dataset were fully replaced with data from CPC whose anomalies were calculated with respect to the 1981-2010 base period. Before this date, SOI data values in this dataset before January 2011 contained anomalies calculated with respect to the 1971-2000 base period, and data from January 2011 onward contained anomalies calculated with respect to the 1981-2010 base period.The data are available here as a dataset, including an interactive data viewer and downloadable data files.
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.