Create a List of Raster Stack Objects From CRU CL v. 2.0 Climatology Variables on Local Disk

This function automates importing CRU CL v. 2.0 climatology data into R from locally available data files and creates a list of raster stacks of the data. If requested, minimum and maximum temperature may also be automatically calculated as described in the data readme.txt file. This function can be useful if you have network connection issues that mean automated downloading of the files using R does not work properly. In this instance it is recommended to use an FTP client (e.g., FileZilla), web browser or command line command (e.g., wget or curl) to download the files, save locally and use this function to import the data into R.

Nomenclature and units from readme.txt:

pre

precipitation (millimetres/month)

rd0

wet-days (number days with >0.1mm 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 windspeed (metres/second)

elv

elevation (automatically converted to metres)

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

create_CRU_stack(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, dsn = "")

Arguments

pre	Logical. Create a raster stack of precipitation (millimetres/month) from local files? Defaults to FALSE.
pre_cv	Logical. Create a raster stack of cv of precipitation (percent) from local files? Defaults to FALSE.
rd0	Logical. Logical. Create a raster stack of wet days (number days with >0.1 millimetres rain per month) from local files? Defaults to FALSE.
tmp	Logical. Create a raster stack of temperature (degrees Celsius) from local files? Defaults to FALSE.
dtr	Logical. Create a raster stack of mean diurnal temperature range (degrees Celsius) from local files? Defaults to FALSE.
reh	Logical. Create a raster stack of relative humidity from local files? Defaults to FALSE.
tmn	Logical. Calculate minimum temperature values (degrees Celsius) and return it in a raster stack? Requires tmp and dtr files to be locally present. Defaults to FALSE.
tmx	Logical. Calculate maximum temperature values (degrees Celsius) and return it in a raster stack? Requires tmp and dtr files to be locally present. Defaults to FALSE.
sunp	Logical. Create a raster stack of sunshine, percent of maximum possible (percent of day length) from local files? Defaults to FALSE.
frs	Logical. Create a raster stack of ground-frost records (number of days with ground-frost per month) from local files? Defaults to FALSE.
wnd	Logical. Create a raster stack of 10m wind speed (metres/second) from local files? Defaults to FALSE.
elv	Logical. Create a raster layer of elevation (converted to metres) from local files? Defaults to FALSE.
dsn	Local file path where CRU CL v. 2.0 .dat.gz files are located.

Value

A list of raster stack objects of CRU CL v. 2.0 climatology elements

Note

This package automatically converts elevation values from kilometres to metres.

This package crops all spatial outputs to an extent of ymin = -60, ymax = 85, xmin = -180, xmax = 180. Note that the original wind data include land area for parts of Antarctica, these data are excluded in the raster stacks generated by this function.

See also

get_CRU_stack

Examples

# Create a raster stack of precipitation and temperature from pre and tmp
# files in the Downloads directory.
# NOT RUN {
CRU_pre_tmp <- create_CRU_stack(pre = TRUE, tmp = TRUE, dsn = "~/Downloads")
# }