d3.contours from a netCDF file, after Patrick Brockmann
R/ncdfV4toV3.R
converts the CMORPH data to the proper .nc classic format. Currently, GitHub Actions run the script daily at 10am UTC. See the Observable notebook for the live version of the globe.
For more information on the CMORPH SPI dataset, see drought.gov. Thanks to Chad Small for the assist!