Determine means of selected grid boxes
The function determines means of selected grid boxes from data of a single CM SAF NetCDF input file.
gridboxmean( var, lonGrid, latGrid, infile, outfile, nc34 = 4, overwrite = FALSE, verbose = FALSE )
var |
Name of NetCDF variable (character). |
lonGrid |
INTEGER Number of grid boxes in x direction |
latGrid |
INTEGER Number of grid boxes in y direction |
infile |
Filename of input NetCDF file. This may include the directory (character). |
outfile |
Filename of output NetCDF file. This may include the directory (character). |
nc34 |
NetCDF version of output file. If |
overwrite |
logical; should existing output file be overwritten? |
verbose |
logical; if TRUE, progress messages are shown |
A NetCDF file including a time series of means of selected grid boxes is written.
Other grid boxes statistics:
gridboxmax(),
gridboxmin(),
gridboxrange(),
gridboxsd(),
gridboxsum(),
gridboxvar()
## Create an example NetCDF file with a similar structure as used by CM
## SAF. The file is created with the ncdf4 package. Alternatively
## example data can be freely downloaded here: <https://wui.cmsaf.eu/>
library(ncdf4)
## create some (non-realistic) example data
lon <- seq(5, 15, 0.5)
lat <- seq(45, 55, 0.5)
time <- seq(as.Date("2000-03-01"), as.Date("2000-05-31"), "month")
origin <- as.Date("1983-01-01 00:00:00")
time <- as.numeric(difftime(time, origin, units = "hour"))
data <- array(250:350, dim = c(21, 21, 3))
## create example NetCDF
x <- ncdim_def(name = "lon", units = "degrees_east", vals = lon)
y <- ncdim_def(name = "lat", units = "degrees_north", vals = lat)
t <- ncdim_def(name = "time", units = "hours since 1983-01-01 00:00:00",
vals = time, unlim = TRUE)
var1 <- ncvar_def("SIS", "W m-2", list(x, y, t), -1, prec = "short")
vars <- list(var1)
ncnew_1 <- nc_create(file.path(tempdir(), "CMSAF_example_file.nc"), vars)
ncvar_put(ncnew_1, var1, data)
ncatt_put(ncnew_1, "lon", "standard_name", "longitude", prec = "text")
ncatt_put(ncnew_1, "lat", "standard_name", "latitude", prec = "text")
nc_close(ncnew_1)
## Determine the means of selected grid boxes of the example CM SAF NetCDF file
## and write the output to a new file.
gridboxmean(var = "SIS", lonGrid = 4, latGrid = 4, infile = file.path(tempdir(),
"CMSAF_example_file.nc"), outfile = file.path(tempdir(),
"CMSAF_example_file_gridboxmean.nc"))
unlink(c(file.path(tempdir(), "CMSAF_example_file.nc"), file.path(tempdir(),
"CMSAF_example_file_gridboxmean.nc")))Please choose more modern alternatives, such as Google Chrome or Mozilla Firefox.