Maps of the monthly self-calibrating Palmer drought severity index (SCPDSI) have been calculated for the period 1901–2002 for the contiguous United States (20°–50°N and 130°–60°W) and Europe (35°–70°N, 10°W–60°E) with a spatial resolution of 0.5° × 0.5°
National Center for Atmospheric Research Staff (Eds). Last modified 11 Feb 2014. "The Climate Data Guide: CRU sc-PDSI (self-calibrating PDSI) over Europe & North America." Retrieved from https://climatedataguide.ucar.edu/climate-data/cru-sc-pdsi-self-calibrating-pdsi-over-europe-north-america.