Mapping meteorological drought hazard, Mapping hydrological drought hazard

Guttman, N. B., 1999: Accepting the standardized precipitation index: A calculation algorithm. J. Amer. Water Resour. Assoc., 35, 311-322. Haylock, M. R., N. Hofstra, A. M. G. Klein Tank, E. J. Klok, P. D. Jones and M. New, 2008: A European daily high-resolution gridded dataset of surface temperature and precipitation. J. Geophys. Res. (Atmospheres), 113, D20119, doi:10.1029/2008JD10201 McKee, T. B., J. Nolan, and J. Kleist, 1993: The relationship of drought frequency and duration to time scales. Preprints, Eighth Conf. on Applied Climatology, Anaheim, CA, Amer. Meteor, Soc., 179- 184. McKee, T. B., J. Nolan, and J. Kleist, 1995: Drought monitoring with multiple time scales. Preprints, Ninth Conf. on Applied Climatology, Dallas, TX, Amer. Meteor. Soc., 233-236.

None

eng

Europe

Europe

Mapping meteorological drought hazard, Mapping hydrological drought hazard

Data requirements to use: None;

Data used: SYNOP, GPCC, E-OBS precipitation estimates/observations;

Data format: N/A;

Data access: website;

Concise description:

Computation of the SPI involves fitting a probability density function to a given frequency distribution of precipitation totals for a station or grid point and for an accumulation period. For EDO we use the gamma probability density function. The statistics for the frequency distribution are calculated on the basis of a reference period of at least 30 years (see point 2.b). - 4 - DESERT Action – LMNH Unit SPI Factsheet The parameters of the probability density function are then used to find the cumulative probability of the observed precipitation for the required month and temporal scale. This cumulative probability is then transformed to the standardized normal distribution with mean zero and variance one, which results in the value of the SPI. The procedure of transforming the observed rainfall via the cumulative distribution functions (CDF) of the Gamma distribution and the standardized normal variable to the SPI is illustrated in Figure 1:

eng

European Drought Observatory -Standardized Precipitation Index

ISO 19115:2003/19139

1.0

http://edo.jrc.ec.europa.eu/edov2/php/index.php?id= 1111