SPEI Global Drought Monitor

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The SPEI Global Drought Monitor offers near real-time information about drought conditions at the global scale, with a 0.5 degrees spatial resolution and a monthly time resolution. SPEI time-scales between 1 and 48 months are provided. The calibration period for the SPEI is January 1950 to December 2010.

The dataset is updated during the first days of the following month based on the most reliable and updated sources of climatic data. Mean temperature data are obtained from the NOAA NCEP CPC GHCN_CAMS gridded dataset. Monthly precipitation sums data are obtained from the Global Precipitation Climatology Centre (GPCC). Data from the 'first guess' GPCC product, with an original resolution of 1º, are interpolated to the resolution of 0.5º.

Currently, the SPEI Global Drought Monitor is based on the Thortnthwaite equation for estimating potential evapotranspiration, PET. This is due to the lack of real-time data sources for computing more robust PET estimations which have larger data requirements. The main advantage of the SPEI Global Drought Monitor is thus its near real-time character, a characteristic best suited for drought monitoring and early warning purposes. For long-term analysis, however, other datasets are to be preferred that rely on more robust methods of PET estimation. Use of the SPEIbase dataset, which is based on the FAO-56 Penman-Monteith model, is thus recommended for climatological studies of drought.


The data from SPEI Global Drought Monitor is made available under the Open Database License. Any rights in individual contents of the database are licensed under the Database Contents License.

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