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Western Tropical Indian Ocean (WTIO) SST index

The WTIO SST anomaly index is an indicator of the surface temperatures in a cross-equatorial region spanning the western tropical Indian Ocean. It is one half of the Dipole Mode Index, an indicator of the east-west gradient in sea surface temperatures in the Indian Ocean. It is calculated with SSTs in the box 50°E - 70°E, 10°S - 10°N.

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 »