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. We used the definition in Ropelewski 1987 MWR. Surface pressure at the grid points nearest to Tahiti and Darwin represent the timeseries at those two locations. Each timeseries is first standardized using the 1981-2010 monthly climatology. Th e Tahiti minus Darwin timeseries is calculated. This timeseries is then re-normalized using the entire time period for the standardization.

Time Interval: Monthly
Time Coverage: 1871 to 2010
Update Status: None

Get Data:

SOI: Standard PSL Format (What is standard format?)

Source:
Data is from PSL from the 20CR dataset
References:

1. Ropelewski, C.F. and Jones, P.D., 1987: An extension of the Tahiti-Darwin Southern Oscillation Index. Monthly Weather Review, 115, 2161-2165.
2. NOAA/NCEP Climate Prediction Center (CPC) SOI monitoring data

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