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Create a data.table of CRU CL v. 2.0 climatology elements

Source: R/read_cru_dt.R
read_cru_dt.Rd

Automates importing CRU CL v.2.0 climatology data and from either the CRU server or local files and creates a data.table of the data. If requested, minimum and maximum temperature may also be calculated as described in the data readme.txt file and returned.

Usage

read_cru_dt(
  pre = FALSE,
  pre_cv = FALSE,
  rd0 = FALSE,
  tmp = FALSE,
  dtr = FALSE,
  reh = FALSE,
  tmn = FALSE,
  tmx = FALSE,
  sunp = FALSE,
  frs = FALSE,
  wnd = FALSE,
  elv = FALSE,
  x = NULL
)

Source

pre

https://crudata.uea.ac.uk/cru/data/hrg/tmc/grid_10min_pre.dat.gz

rd0

https://crudata.uea.ac.uk/cru/data/hrg/tmc/grid_10min_rd0.dat.gz

tmp

https://crudata.uea.ac.uk/cru/data/hrg/tmc/grid_10min_tmp.dat.gz

dtr

https://crudata.uea.ac.uk/cru/data/hrg/tmc/grid_10min_dtr.dat.gz

reh

https://crudata.uea.ac.uk/cru/data/hrg/tmc/grid_10min_reh.dat.gz

sunp

https://crudata.uea.ac.uk/cru/data/hrg/tmc/grid_10min_sunp.dat.gz

frs

https://crudata.uea.ac.uk/cru/data/hrg/tmc/grid_10min_frs.dat.gz

wnd

https://crudata.uea.ac.uk/cru/data/hrg/tmc/grid_10min_wnd.dat.gz, areas originally including Antarctica are removed.

elv

https://crudata.uea.ac.uk/cru/data/hrg/tmc/grid_10min_elv.dat.gz, values are converted from kilometres to metres.

This package crops all spatial outputs to an extent of ymin = -60, ymax = 85, xmin = -180, xmax = 180.

Arguments

pre

Read precipitation (millimetres/month) and return it, TRUE. Defaults to FALSE.

pre_cv

Read cv of precipitation (percent) and return it, TRUE. Defaults to FALSE. NOTE. Setting this to TRUE will always results in pre being set to TRUE and returned as well.

rd0

Read wet-days (number days with >0.1 millimetres rain per month) and return it, TRUE. Defaults to FALSE.

tmp

Reads temperature (degrees Celsius) and return it, TRUE. Defaults to FALSE`.

dtr

Read mean diurnal temperature range (degrees Celsius) and return it, TRUE. Defaults to FALSE.

reh

Read relative humidity and return it, TRUE. Defaults to FALSE.

tmn

Calculate minimum temperature values (degrees Celsius) and return it, TRUE. Defaults to FALSE.

tmx

Calculate maximum temperature (degrees Celsius) and return it, TRUE. Defaults to FALSE.

sunp

Read sunshine, percent of maximum possible (percent of day length) and return it, TRUE. Defaults to FALSE.

frs

Read ground-frost records (number of days with ground- frost per month) and return it, TRUE. Defaults to FALSE.

wnd

Read 10 m wind speed (metres/second) and return it, TRUE. Defaults to FALSE.

elv

Read elevation (converted to metres) and return it, TRUE. Defaults to FALSE.

x

An optional local file path where CRU CL v.2.0 .dat.gz files are located. If this is empty, the requested data will automatically be downloaded from the server.

Value

A data.table::data.table object of CRU CL v. 2.0 climatology elements.

Nomenclature and Units

pre

precipitation (millimetres/month)

rd0

wet-days (number days with >0.1 millimetres rain per month)

tmp

mean temperature (degrees Celsius)

dtr

mean diurnal temperature range (degrees Celsius)

reh

relative humidity (percent)

sunp

sunshine (percent of maximum possible (percent of day length))

frs

ground-frost (number of days with ground-frost per month)

wnd

10 metre wind speed (metres/second)

elv

elevation (automatically converted to metres from kilometres)

For more information see the description of the data provided by CRU, https://crudata.uea.ac.uk/cru/data/hrg/tmc/readme.txt

References

New, Mark, et al. "A high-resolution data set of surface climate over global land areas." Climate research 21.1 (2002): 1-25. https://crudata.uea.ac.uk/cru/data/hrg/tmc/new_et_al_10minute_climate_CR.pdf

See also

read_cru_rast.

Author

Adam H. Sparks, adamhsparks@gmail.com

Examples

if (FALSE) { # interactive()
# Create a data frame of temperature from locally available files in the
# tempdir() directory.
library(fs)

f <- path(path_temp(), "grid_10min_tmp.dat.gz")

download.file(
  url = "https://crudata.uea.ac.uk/cru/data/hrg/tmc/grid_10min_tmp.dat.gz",
  destfile = f
)


cru_tmp <- read_cru_dt(tmp = TRUE, x = f)

cru_tmp

# or downloading directly from the CRU server

cru_tmp <- read_cru_dt(tmp = TRUE)

cru_tmp
}