Crops:
United States Department of Agriculture (USDA)- National Agricultural Statistics Service (NASS) https://www.nass.usda.gov/Quick_Stats/
ERSST:
Boyin Huang, Peter W. Thorne, Viva F. Banzon, Tim Boyer, Gennady Chepurin, Jay H. Lawrimore, Matthew J. Menne, Thomas M. Smith, Russell S. Vose, and Huai-Min Zhang (2017): NOAA Extended Reconstructed Sea Surface Temperature (ERSST), Version 5. [global]. NOAA National Centers for Environmental Information. doi: 10.7289/V5T72FNM [2019].
GPCC Precipitation:
GPCC Precipitation data provided by the NOAA/OAR/ESRL PSD, Boulder, Colorado, USA, from their Web site at https://www.esrl.noaa.gov/psd/
IMERG Precipitation:
Huffman, G.J., E.F. Stocker, D.T. Bolvin, E.J. Nelkin, Jackson Tan (2019), GPM IMERG Final Precipitation L3 1 month 0.1 degree x 0.1 degree V06, Greenbelt, MD, Goddard Earth Sciences Data and Information Services Center (GES DISC), Accessed: [June 2019], 10.5067/GPM/IMERG/3B-MONTH/06
NCEP/NCAR Temperature:
NCEP Reanalysis data provided by the NOAA/OAR/ESRL PSD, Boulder, Colorado, USA, from their Web site at https://www.esrl.noaa.gov/psd/
NDVI:
Didan, K. (2015). MOD13C2 MODIS/Terra Vegetation Indices Monthly L3 Global 0.05Deg CMG V006 [MOD13C2]. NASA EOSDIS Land Processes DAAC. doi: 10.5067/MODIS/MOD13C2.006
PDSI:
Dai, Aiguo & National Center for Atmospheric Research Staff (Eds). Last modified 18 Jul 2019. “The Climate Data Guide: Palmer Drought Severity Index (PDSI).” Retrieved from https://climatedataguide.ucar.edu/climate-data/palmer-drought-severity-index-pdsi.
River Flow: https://www.bafg.de/GRDC/EN/02_srvcs/21_tmsrs/riverdischarge_node.html
SPEI:
Vicente‐Serrano, S. M., S. Begueria, J. I. Lopez‐Moreno, M. Angulo, and A. El Kenawy (2010b), A new global 0.5 degrees gridded dataset (1901–2006) of a multiscalar drought index: Comparison with current drought index datasets based on the Palmer Drought Severity Index, J. Hydrometeorol., 11, 1033–1043, doi:10.1175/2010JHM1224.1.