0

I usually calculate monthly or 3-monthly Standardized Precipitation Index (SPI) using spreadsheet, based on daily rainfall from weather station. Attached is the spreadsheet example link.

And now I would like to use satellite precipitation estimate (raster data) to calculate the SPI. The problem is in the spreadsheet I use some function like: FREQUENCY, GAMA.DIST, NORMSINV.

Is there any similar above function in ArcGIS Desktop?

Improve this question

2 Answers 2

Reset to default
2

Here you can find ArcGIS toolbox for calculating SPI. This toolbox was made with the same algorithm in the spreadsheet.

https://github.com/Hyun-Woo-Jo/CalculateSPI/releases/tag/v1.0

Improve this answer
5
1

There was a discussion at GeoNet titled How to calculate Standard Precipitation Index (SPI) using ArcGIS which suggests that there is a way to "calculate the SPI using monthly CHIRPS CHG - Data" using the Cell Statistics tool in the Spatial Analyst toolbox.

Improve this answer
2
  • Yes thank you, I answered that question. At that time, I found that was the simple approach to calculate the SPI using the long-term average and stdev. Then recently I found that method is not perfectly correct, we need to calculate the gamma distribution. So thats why I ask above question in here.
    – user97103
    Commented Dec 5, 2019 at 11:10
  • 1
    @user97103 You should probably have mentioned this in the question, no?
    – Vince
    Commented Dec 5, 2019 at 12:28

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.