deviationThroughTime: Calculating deviation through time

In climateStability: Estimating Climate Stability from Climate Model Data

Calculating deviation through time

Description

A function that reads time-slice rasters of data for a given climate (typically processed data from a climate model run, such as the results of an analysis using PaleoView (Fordham, *et al.* 2017, Ecography)) in a given directory and calculates average deviation per year across time slices.

Usage

deviationThroughTime(variableDirectory, timeSlicePeriod, fileExtension = "asc")

Arguments

variableDirectory	A directory containing at least two time slice rasters for a given climate variable.
timeSlicePeriod	Either a single number, in years, representing the time period elapsed between temporally-even climate variable raster slices, or a vector corresponding to periods, in years, between temporally-uneven time slices.
fileExtension	a character that describes a fileExtension corresponding to one of the suported drivers in gdal

Details

Make sure that files in the 'variableDirectory' are read into 'R' in order.

If you are specifying temporally-uneven time slices with 'timeSlicePeriod', make sure that each number corresponds to the number of years elapsed *between* time slices, *in the same order as the files were read into 'R'*. There should be one less number than the number of files, and you must have at least three files in the directory.

See 'precipDeviation.asc' and 'temperatureDeviation.asc' for examples of rasters created using this function. See reference for data source details.

Value

A raster showing the geographic distribution of climate deviation through time for a particular climate variable.

References

Owens, H.L., Guralnick, R., 2019. climateStability: An R package to estimate climate stability from time-slice climatologies. Biodiversity Informatics 14, 8–13. https://doi.org/10.17161/bi.v14i0.9786

Examples

# Generate sample data
td <- tempdir()
suppressWarnings(x <- terra::rast(nrows=20, ncols=20,
                                  xmin=0, xmax=10, ymin=0, ymax=10,
                                  vals = c(10,10,10,10,20)))
x2 <- x * 1.01
rastStack <- c(x, x2, x)
terra::writeRaster(rastStack, filename = paste0(td, "/raster",
                                                1:terra::nlyr(rastStack), ".tif"),
                   overwrite = TRUE)

# Even time slices
testResult <- deviationThroughTime(td, timeSlicePeriod = 100,
                                   fileExtension = "tif")

# Uneven time slices
testResult <- deviationThroughTime(variableDirectory = td,
                                   timeSlicePeriod = c(25, 100),
                                   fileExtension = "tif")
# Delete temporary files
unlink(td)

climateStability documentation built on Oct. 1, 2022, 9:05 a.m.