Niño1+2

The Niño1+2 SST anomaly index is an indicator of far eastern tropical Pacific El Niño conditions, off the coasts of Peru and Chile. It is calculated with SSTs in the box 90°W - 80°W, 10°S - 0°.

Data source

The index is calculated using the Reynolds OIv2 SST analysis, made available through the IRI Data Library, and is updated weekly (last update 26-OCT-2016). get series (netcdf 24kB) » get error (netcdf 24kB) »

Calculation

The anomaly is calculated relative to a climatological seasonal cycle based on the years 1982-2005. The weekly series was linearly interpolated to a daily series to calculate the climatological seasonal cycle with daily resolution. The leap day (29 February) was treated as a special case and linearly interpolated between the climatology of 28 February and 1 March. Spatial averaging of the gridded analysis was weighted by surface area. The standard deviation of the index over the period 1982-2005 is indicated on the plot.

Uncertainty

The uncertainty in the estimate of the index is shown in gray, surrounding the zero x-axis, and is based on the uncertainty estimate of the analysis. For the surface indices, it is generally small compared to the value of the index. more details »

OOPC Secretariat - IOC/UNESCO - 1 rue Miollis - 75732 Paris cedex 15 - France