Standardized Climate Indices Such as SPI, SRI or SPEI

Description

Functions for generating Standardized Climate Indices (SCI). SCI is a transformation of (smoothed) climate (or environmental) time series that removes seasonality and forces the data to take values of the standard normal distribution. SCI was originally developed for precipitation. In this case it is known as the Standardized Precipitation Index (SPI).

Details

Package: SCI
Type: Package
Version: 1.0-2
Date: 2016-05-02
License: GPL (>= 2)

Author(s)

Lukas Gudmundsson & James Stagge

Maintainer: Lukas Gudmundsson <lukas.gudmundsson@env.ethz.ch>

References

Stagee, J.H. ; Tallaksen, L.M.; Gudmundsson, L.; van Loon, A.; Stahl, K.: Candidate Distributions for Climatological Drought Indices (SPI and SPEI), 2015, International Journal of Climatology, 35, 4027-4040, doi:10.1002/joc.4267.

Stagee, J.H. ; Tallaksen, L.M.; Gudmundsson, L.; van Loon, A.; Stahl, K.: Response to comment on "Candidate Distributions for Climatological Drought Indices (SPI and SPEI)", 2016, International Journal of Climatology, 36, 2132-2138, doi:10.1002/joc.4564.

Examples

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## create artificial data, resembling precipitation
set.seed(101)
n.years <- 60
date <- rep(1:n.years,each=12) + 1950 + rep((0:11)/12,times=n.years)
PRECIP <- (0.25*sin( 2 * pi * date) + 0.3)*rgamma(n.years*12, shape = 3, scale = 1)
PRECIP[PRECIP<0.1] <- 0

## apply SCI transformation
spi.para <- fitSCI(PRECIP,first.mon=1,time.scale=6,distr="gamma",p0=TRUE)
spi <- transformSCI(PRECIP,first.mon=1,obj=spi.para)
plot(date,spi,t="l")