multimonsum {cmsafops}R Documentation

Determine multi-monthly sums

Description

The function determines multi-monthly sums from data of a single CM SAF NetCDF input file. The months are given as a vector of integers from 1 to 12. This allows sums of user-defined seasons.

Usage

multimonsum(
  var,
  month = c(1),
  infile,
  outfile,
  nc34 = 4,
  overwrite = FALSE,
  verbose = FALSE,
  nc = NULL
)

Arguments

var

Name of NetCDF variable (character).

month

Months which should be averaged, in form of a comma separated vector of integer values from 1 to 12 (integer).

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 nc34 = 3 the output file will be in NetCDFv3 format (numeric). Default output is NetCDFv4.

overwrite

logical; should existing output file be overwritten?

verbose

logical; if TRUE, progress messages are shown

nc

Alternatively to infile you can specify the input as an object of class ncdf4 (as returned from ncdf4::nc_open).

Value

A NetCDF file including a time series of multi-monthly sums is written.

See Also

Other monthly statistics: mon.anomaly(), mon_num_above(), mon_num_below(), mon_num_equal(), monavg(), mondaymean(), monmax(), monmean(), monmin(), monpctl(), monsd(), monsum(), monvar(), multimonmean(), ymonmax(), ymonmean(), ymonmin(), ymonsd(), ymonsum()

Examples

## 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(10, 15, 0.5)
lat <- seq(50, 55, 0.5)
time <- seq(as.Date("2000-01-01"), as.Date("2010-12-31"), "month")
origin <- as.Date("1983-01-01 00:00:00")
time <- as.numeric(difftime(time, origin, units = "hour"))
data <- array(0:150, dim = c(11, 11, 132))

## 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("rain", "mm", list(x, y, t), -1, prec = "short")
vars <- list(var1)
ncnew <- nc_create(file.path(tempdir(),"CMSAF_example_file.nc"), vars)
ncvar_put(ncnew, var1, data)
ncatt_put(ncnew, "lon", "standard_name", "longitude", prec = "text")
ncatt_put(ncnew, "lat", "standard_name", "latitude", prec = "text")
nc_close(ncnew)

## Determine the sum of the monsoon seas from June to September of the
## example CM SAF NetCDF file and write the output to a new file.
multimonsum(var = "rain", month = c(6, 7, 8, 9), infile = 
 file.path(tempdir(),"CMSAF_example_file.nc"), outfile =
 file.path(tempdir(),"CMSAF_example_file_multimonsum.nc"))

unlink(c(file.path(tempdir(),"CMSAF_example_file.nc"), 
 file.path(tempdir(),"CMSAF_example_file_multimonsum.nc")))

[Package cmsafops version 1.3.0 Index]