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Environmental Information Data Centre

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This dataset provides Standardised Precipitation Index (SPI) values for Integrated Hydrological Units (IHU) groups in the United Kingdom, published by the Environmental Information Data Centre. SPI is a drought index derived from the probability of precipitation over a given accumulation period, calculated here for 1, 3, 6, 12, 18 and 24-month periods for each calendar month, using a gamma distribution fitted to the 1961-2010 standard period. The dataset spans 1961-2012. Monthly and longer-period time series may exhibit autocorrelation. It is based on methods from Kral et al. (2015) and McKee et al. (1993), useful for hydrological and drought analysis.Standardised Precipitation Index (SPI) data for Integrated Hydrological Units (IHU) groups (Kral et al. [1]). SPI is a drought index based on the probability of precipitation for a given accumulation period as defined by McKee et al. [2]. SPI is calculated for different accumulation periods: 1, 3, 6, 12, 18, 24 months. Each of these is in turn calculated for each of the twelve calendar months. Note that values in monthly (and for longer accumulation periods also annual) time series of the data therefore are likely to be autocorrelated. The standard period which was used to fit the gamma distribution is 1961-2010. The dataset covers the period from 1961 to 2012. [1] Kral, F., Fry, M., Dixon, H. (2015). Integrated Hydrological Units of the United Kingdom: Groups. NERC-Environmental Information Data Centre https://doi.org/10.5285/f1cd5e33-2633-4304-bbc2-b8d34711d902 [2] McKee, T. B., Doesken, N. J., Kleist, J. (1993). The Relationship of Drought Frequency and Duration to Time Scales. Eighth Conference on Applied Climatology, 17-22 January 1993, Anaheim, California. Full details about this dataset can be found at https://doi.org/10.5285/dfd59438-2170-4472-b810-bab33a83d09f.