Get CHIRPS precipitation data

Get daily precipitation data from the "Climate Hazards Group". Two server sources are available. The first, "CHC" (default) is recommended for multiple data-points, while "ClimateSERV" is recommended when few data-points are required (~ 50).

Usage

get_chirps(object, dates, server, ...)

# Default S3 method
get_chirps(object, dates, server, as.matrix = FALSE, ...)

# S3 method for class 'SpatVector'
get_chirps(object, dates, server = "CHC", as.raster = TRUE, ...)

# S3 method for class 'SpatRaster'
get_chirps(
  object,
  dates,
  server = "CHC",
  as.matrix = TRUE,
  as.raster = FALSE,
  ...
)

# S3 method for class 'SpatExtent'
get_chirps(object, dates, server = "CHC", as.raster = TRUE, ...)

# S3 method for class 'sf'
get_chirps(object, dates, server, as.sf = FALSE, ...)

# S3 method for class 'geojson'
get_chirps(object, dates, server, as.geojson = FALSE, ...)

# S3 method for class 'SpatExtent'
get_chirps(object, dates, server = "CHC", as.raster = TRUE, ...)

Arguments

object: input, an object of class data.frame (or any other object that can be coerced to data.frame), SpatVector, SpatRaster, sf or geojson
dates: a character of start and end dates in that order in the format "YYYY-MM-DD"
server: a character that represents the server source "CHC" or "ClimateSERV"
...: additional arguments passed to terra or sf methods See details
as.matrix: logical, returns an object of class matrix
as.raster: logical, returns an object of class SpatRaster
as.sf: logical, returns an object of class sf
as.geojson: logical, returns an object of class geojson

Value

A matrix, raster or a data frame of CHIRPS data:

id: the index for the rows in object
dates: the dates from which CHIRPS was requested
lon: the longitude as provided in object
lat: the latitude as provided in object
chirps: the CHIRPS value in mm

Details

Data description at https://data.chc.ucsb.edu/products/CHIRPS-2.0/README-CHIRPS.txt

Additional arguments when using server = "CHC"

resolution: numeric, resolution of CHIRPS tiles either 0.05 (default) or 0.25 degrees

Additional arguments when using server = "ClimateSERV"

dist: numeric, buffer distance for each object coordinate

nQuadSegs: integer, number of segments per buffer quadrant

operation: supported operations for ClimateSERV are:

operation		value
max	=	0
min	=	1
median	=	2
sum	=	4
average	=	5 (default value)

Note

get_chirps() may return some warning messages given by sf, please look sf documentation for possible issues.

References

Funk C. et al. (2015). Scientific Data, 2, 150066.
doi:10.1038/sdata.2015.66

Examples

if (FALSE) { # interactive()
library("chirps")
library("terra")

# Case 1: return as a data.frame
dates <- c("2017-12-15","2017-12-31")
lonlat <- data.frame(lon = c(-55.0281,-54.9857), lat = c(-2.8094, -2.8756))

r1 <- get_chirps(lonlat, dates, server = "CHC")

# Case 2: return a matrix
r2 <- get_chirps(lonlat, dates, server = "CHC", as.matrix = TRUE)

# Case 3: input SpatVector and return raster
f <- system.file("ex/lux.shp", package = "terra")
v <- vect(f)
r3 <- get_chirps(v, dates, server = "CHC", as.raster = TRUE)

# Case 4: input SpatExtent and return a raster within the extent
area <- ext(c(-66, -64, -6, -4))

dates <- c("2017-12-15", "2017-12-31")

r4 <- get_chirps(area, dates, server = "CHC")

# Case 5: using the server "ClimateSERV"
r5 <- get_chirps(lonlat, dates, server = "ClimateSERV")

# Case 6: from "ClimateSERV" and return as a matrix
r6 <- get_chirps(lonlat, dates, server = "ClimateSERV", as.matrix = TRUE)

}