Computing yourself when a Drought occurs
The Standard Precipitation Index
allows you to assess whether a drought is evolving. It is the most common index used to alert for the onset of a disaster.
With this program you can compute every month at a resolution of 1 decimal degree the so-called Standard Precipitation Index (SPI) for the whole terrestial earth. We provide you three programs and three NetCDF databases to acomplish this.
The programs use the OpenSource software R to compute the Index and if you want to use the a Spatial Database in addition to the NetCDF files you can synchronize the results with a PostgreSQL/PostGIS database. First you must install R with the following libraries: ncdf4, genkern, lmomco, chron and optionally ROBBC if you want to use the database.
- Program to download monthly rainfall data and integrate them in the NetCDF and/or Spatial Database
- Program to compute the SPI
- Program to upload the results to the Spatial Database (Optional)
- NetCDF database with First Guess monthly Rainfall data
- NetCDF database with higher quality Monitoring Monthly Data
- NetCDF database with longterm average from 1981 to 2010
- NetCDF database with SPI output results
- GRID 1 decimal degree reference table (Optional)
- Rainfall Monthly Downloaded data table (Optional)
- Rainfall SPI results table (Optional)
How to proceed:
First download the input NetCDF databases for first guess and monitoring data. Place them in a directory called for example spi\input.
Then download the reference NetCDF databases (for every timestep 1) and place them in a directoy \spi\ref_1981_2010
Then download the result database (again for every timestep 1 dataset) in place them in a directory \spi\output
Now you can download the 3 programs. The first program comes without parameters. In R a screen will open allowing you to upload monthly data, either first guess or monitoring. Usually monitoring data arrive of the 25th day of the month, valid for 2 months earlier. At the 4th of the month the first guess data of the previous month arrive. You upload both and on the 5th of every month you can do the computation.
In the computation program you will have to adapt the paths to the 3 sets of NetCDF files to the reality of the PC or Mac you are using. You can check the MapServer of Scado or GDO whether your results are compliant. Also sources provided can be freely adapted to your own needs. Whenever using it please make a reference to SCADO and it websites.