This metadata record describes the annual average number of occurrences of dry and wet events during the 30-year period 1981-2010 for the conterminous United States. A wet event is defined as a period
Summary: The Global Precipitation Climatology Centre drought index (GPCC_DI) is a combination of the Standardized Precipitation Index (SPI; McKee et al., 1993) with the DWD modification according to P