Gridded Standardized Precipitation Index (SPI) using gamma distribution with standard period 1961-2010 for Great Britain [SPIgamma61-10]

1km and 5km gridded Standardised Precipitation Index (SPI) data for Great Britain, which is a drought index based on the probability of precipitation for a given accumulation period as defined by McKee et al. (1993). 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.

英国1公里和5公里网格分辨率的标准化降水指数（Standardised Precipitation Index, SPI）数据，该指数是一种干旱指数，基于特定累积期降水概率计算，由McKee等人（1993）定义。SPI针对不同累积期计算：1、3、6、12、18、24个月。每种累积期又针对十二个日历月分别计算。请注意，该数据的月度（对于较长累积期还包括年度）时间序列值可能存在自相关（autocorrelated）。拟合伽马分布（gamma distribution）所用的标准期为1961-2010年。该数据集的时间覆盖范围为1961-2012年。