SPI standard precipitation index

• T. B. McKee, N. J. Doesken and J. Kleist: THE RELATIONSHIP OF DROUGHT FREQUENCY AND DURATION TO TIME SCALES. Eighth Conference on Applied Climatology, 17-22 January 1993, Anaheim, California
• T. B. McKee, N. J. Doesken and J. Kleist, “Drought Monitoring with Multiple Time Scales,” Proceedings of the 9th Conference on Applied Climatology, 15-20 January 1995, Dallas, TX, American Meteorological Society, pp. 233-236.

• https://github.com/e-baumer/standard_precip

$ unzip standard_precip-master.zip
$ cd standard_precip-master/examples/
$ cp -pr ../standard_precip ./
$ jupyter-notebook example_use.ipynb

• https://climate-indices.readthedocs.io/en/latest/