SPEI Global Drought Monitor

Information

The SPEI products of the drought monitoring system are using the Thortnthwaite equation to obtain the PET. This is due to the lack of the necessary global information to calculate PET by means of the FAO-56 Penman-Monteith at the real-time. Only monthly precipitation and mean temperature observations are globally available at the necessary real time to be used in a drought monitoring system. Real-time mean monthly temperature is obtained at a resolution of 0.5º from the NOAA NCEP CPC GHCN_CAMS gridded dataset, which is updated the first week of each month (ftp://ftp.cpc.ncep.noaa.gov/wd51yf/GHCN_CAMS/). The necessary monthly precipitation is obtained from the Global Precipitation Climatology Centre (GPCC), which provides the monthly precipitation sums around the 5th day of the following month (ftp://ftp-anon.dwd.de/pub/data/gpcc/first_guess/). The SPEI global drought monitor provides SPEI time-scales of 1- to 48-months. It allows downloading time series of specific points and the complete dataset in netCDF format. This dataset is a different product that the SPEIbase v.2. It may be less accurate for scientific studies since climate inputs of the CRU TS3.10.01 dataset, from which the SPEIbase v.2 is obtained, are carefully quality controlled and homogenized, and they allow obtaining the PET by means of the FAO-56 Penman-Monteith model. Nevertheless, the data available from the drought monitoring system may allow having updated SPEI series each month, which may be useful for different purposes.