cmsaf (version 1.9.5)

multimonsum: 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, infile, outfile, nc34)

Arguments

var

Name of NetCDF variable (character).

month

Months, which should be summed, in form of a comma seperated 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=4 the output file will be in NetCDFv4 format (numeric). Default output is NetCDFv3.

Value

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

Examples

# NOT RUN {
## 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('2000-01-01'), 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(21,21,132))

## 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('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('rain',c(6,7,8,9),'CMSAF_example_file.nc', 
   'CMSAF_example_file_multimonsum.nc')
# }