The daily precipitation data was extracted as .NC files from the CPC global unified gauge-based analysis of precipitation provided by the 
NOAA/OAR/ESRL PSL, Boulder, Colorado, USA (https://psl.noaa.gov/). 

This type of file can be opened and the data extracted in a number of different programs. 

R statistical software was used in our study. The following online links might be useful if R statistical software is going to be used:

https://pjbartlein.github.io/REarthSysSci/netCDF.html

https://www.rpubs.com/boyerag/297592

https://rpubs.com/markpayne/358146

https://stackoverflow.com/questions/50204653/how-to-extract-the-data-in-a-netcdf-file-based-on-a-shapefile-in-r