Pixel-wise Standardized Precipitation Index (SPI) calculation of monthly rainfall raster in R

Asked Dec 06 '19 at 13:22

Active Dec 08 '19 at 15:47

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I want to calculate Standardized Precipitation Index (SPI) of monthly rainfall raster in R. I have seen one question related to this in SO (R Standardized Precipitation Index .nc file), but it was not having any answers. So, I am putting a new question. I have downloaded the monthly rainfall data from the following source https://crudata.uea.ac.uk/cru/data/hrg/cru_ts_4.03/cruts.1905011326.v4.03/pre/

I have read it in R using raster package.

library(raster)
file <- "cru_ts4.03.1901.2018.pre.dat.nc"
rain <- brick(file)

I know it can be done using calc function of raster package and for SPI calculation many packages are available in R (e.g. spi, SPEI, precintcon). I am able to calculate SPI for point data. But I am unable to use the calc function for SPI calculation of raster data. Now my question is how to calculate SPI on this raster at different time scales (1, 2, 3, 6, 12, 24)?

asked Dec 06 '19 at 13:22

UseR10085

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Did you find a solution to your problem yet? I need to calculate SPI for a raster. – avocado1 Feb 28 '20 at 16:47
No not yet..... – UseR10085 Feb 29 '20 at 01:49
@BappaDas why don't you extract the values of each pixel as a vector and then do the standardized estimation? – Felix Phl Jul 21 '20 at 10:16
@FelixPhl Can you please provide sample code? – UseR10085 Jul 21 '20 at 10:27
@BappaDas I checked the above linked SO thread and there is an answer that does exactly what you want – Felix Phl Jul 21 '20 at 10:37

Pixel-wise Standardized Precipitation Index (SPI) calculation of monthly rainfall raster in R

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