Standardized Precipitation Index (SPI) for Global Land Surface (1949-2012)

It was produced for a study to determine the relationship between climate variability and armed conflict in Sub-Saharan Africa (O'Loughlin et al. 2012). The precipitation data (1949-2012) are resampled from the original University of East Anglia Climate Research Unit (CRU) global time series, TS3.21, monthly 0.5 degree by 0.5 degree grids to the study unit of analysis, 1.0 degree by 1.0 degree grids, thereby facilitating regression with environmental and socioeconomic variables.

The Standardized Precipitation Index (SPI) is commonly used to monitor drought and anomalous wet periods. It was formulated by Tom McKee, Nolan Doesken, and John Kleist of the Colorado Climate Center, Colorado State University (McKee et al. 1993). The SPI at a given location is based only on the long-term precipitation record for a desired period.