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

Automates importing CRU CL v.2.0 climatology data and creates a stack 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. Fetch precipitation (millimetres/month) from server and return in the data frame? Defaults to `FALSE`.
pre_cv	Logical. Fetch cv of precipitation (percent) from server and return in the data frame? Defaults to `FALSE`. NOTE. Setting this to `TRUE` will always results in pre being set to `TRUE` and returned as well.
rd0	Logical. Fetch wet-days (number days with >0.1millimetres rain per month) and return in the data frame? Defaults to `FALSE`.
tmp	Logical. Fetch temperature (degrees Celsius) and return it in the data frame? Defaults to `FALSE`.
dtr	Logical. Fetch mean diurnal temperature range (degrees Celsius) and return it in the data frame? Defaults to `FALSE`.
reh	Logical. Fetch relative humidity and return it in the data frame? Defaults to `FALSE`.
tmn	Logical. Calculate minimum temperature values (degrees Celsius) and return it in the data frame? Defaults to `FALSE`.
tmx	Logical. Calculate maximum temperature (degrees Celsius) and return it in the data frame? Defaults to `FALSE`.
sunp	Logical. Fetch sunshine, percent of maximum possible (percent of day length) and return it in data frame? Defaults to `FALSE`.
frs	Logical. Fetch ground-frost records (number of days with ground- frost per month) and return it in data frame? Defaults to `FALSE`.
wnd	Logical. Fetch 10m wind speed (metres/second) and return it in the data frame? Defaults to `FALSE`.
elv	Logical. Fetch elevation (converted to metres) and return it in the data frame? 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.

Author

Adam H. Sparks, adamhsparks@gmail.com

Examples