The SOI is defined as the normalized pressure difference between Tahiti and Darwin. There are several slight variations in the SOI values calculated at various centres. Here we supply the SOI (from CRU) which is based on the method given by Ropelewski and Jones (1987).

Time Interval: Monthly
Time Coverage: 1866 to Apr 2012
Update Status: Periodically updated

Get Data:

SOI: Standard PSD Format (What is standard format?)
SOI: Original Format

Source:
Data is from CRU via the page http://www.cru.uea.ac.uk/cru/data/soi/.
References:

1. Allan, R.J., Nicholls, N., Jones, P.D. and Butterworth, I.J., 1991: A further extension of the Tahiti-Darwin SOI, early SOI results and Darwin pressure. J. Climate, 4, 743-749.
2. Ko"nnen, G.P., Jones, P.D., Kaltofen, M.H. and Allan, R.J., 1998: Pre-1866 extensions of the Southern Oscillation Index using early Indonesian and Tahitian meteorological readings. J. Climate, 11, 2325-2339.
3. Ropelewski, C.F. and Jones, P.D., 1987: An extension of the Tahiti-Darwin Southern Oscillation Index. Monthly Weather Review, 115, 2161-2165.

This page hosted by: NOAA ESRL Physical Sciences Division Document maintained by Cathy Smith (cathy.smith@noaa.gov) Updated: Apr 23, 2013 14:51:03 MDT http://esrl.noaa.gov/psd/gcos_wgsp/Timeseries/SOI/index.html