Quinn, et al. El Nino Index, 1525-1987

The University of Washington Joint Institute for the Study of the Atmosphere and Ocean (JISAO) offers an El Nino Index covering the years 1525-1987. Please link to the dataset homepage for documentation and to download the data. The information on this WWW page is taken from Quinn, W. H., V. T. Neal, and S. E. Antunez de Mayolo, 1987: El Nino occurrences over the past four and a half centuries. J. Geophys. Res., 92, 14449-14461. The authors based their El Nino identification on a broad range of subjective and objective measures, which are described below. Quinn et al. employed the following six categories. Note that they only began identifying moderate El Ninos (categories 1-3) in 1806. 0 neutral or cold 1 weak moderate 2 moderate 3 &moderate +& 4 strong 5 &strong +& 6 very strong The first data value is for 1525 and it is &strong.& Quinn et al. only began identifying weak-moderate, moderate and &moderate +& El Ninos in 1806. [Summary extracted from the JISAO home page]