Multivariate ENSO Index (MEI) looks at sea surface temperature and atmospheric pressure related to El Nino Southern Oscillation.
http://www.esrl.noaa.gov/psd/enso/mei/
Here are MEI datasets.
1950 to Present
http://www.esrl.noaa.gov/psd/enso/mei/table.html
1871 to 2005
http://www.esrl.noaa.gov/psd/enso/mei.e ... e.ext.html