The timeseries is calculated from the HadISST and the NCEP OI SST Datasets. It is the standardized Nino 12 minus the Niño 4 with a 5 month running mean applied which is then standardized using the 1950-1979 period. There is now a version that just uses the HadISST. This avoids the issue where the OI SST doesn't match the HadISST.

Time Interval: Monthly
Time Coverage: 1870 to present
Update Status: updated monthly

Get Data:

TNI: Standard PSL Format (What is standard format?)
TNI HadISST1.1: Standard PSL Format (What is standard format?)

Source:
Data is from NOAA PSL using the HadISST dataset. Index was originally developed by Kevin Trenberth of NCAR/CGD. PSL is updating the index each month. This version is based on the latest HADISST and NCEP OI datasets.

References:

1. Kevin E. Trenberth and David P. Stepaniak: J. Climate, 14, 1697-1701.

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