Name of the Index Data required Data source Reference
Different SPI time scales SPI-1 Monthly precipitation data Iowa Mesonet website (https://mesonet.agron.iastate.edu/rainfall/) and climate data centers (NOAA (McKee et al., 1993)
SPI-3
SPI-6
SPI-12
Different SPEI time scales SPEI-1 Monthly precipitation and temperature data Iowa Mesonet website (https://mesonet.agron.iastate.edu/) and climate data centers (NOAA) (Vicente-Serrano et al., 2010)
SPEI-3
SPEI-6
SPEI-12
PDSI Monthly precipitation and temperature data, soil water holding capacity Iowa Mesonet website (https://mesonet.agron.iastate.edu/) and climate data centers (NOAA) (Palmer, 1965)
EDDI Temperature, relative humidity, wind speed, and solar radiation data Iowa Mesonet website (https://mesonet.agron.iastate.edu/ ) and climate data centers (NOAA) (Hobbins et al., 2016)
CMI Weekly precipitation and temperature data Iowa Mesonet website (https://mesonet.agron.iastate.ed.u/) and climate data centers (NOAA) (Palmer, 1968)
NDVI Satellite imagery data (visible and near-infrared light) Satellite data providers (NASA’s MODIS) (Rouse Jr et al., 1974)