ccdfvar : computes the spatial variance of field (2D or 3D)

Computes the spatial variance of a 2D or 3D field. This is the wrapping around the native cdfmean operator assuming its usage is:

cdfmean  IN-file IN-var T|U|V|F|W **[imin imax jmin jmax kmin kmax]**
... **[-full]** [-var] [-zeromean]

CliMAF optional arguments are the ones surrounded with ‘**’.

If a spatial window is specified, the spatial variance is computed only in this window. See also:

  • ccdfvar_profile for getting a vertical profile of spatial variance for each level for 3D fields

References :

Provider / contact : climaf at meteo dot fr for the wrapping

Inputs (in the order of CliMAF call):

  • any dataset (but only one)

Mandatory argument:

  • pos_grid : position of cdfvar on the C-grid : T|U|V|F|W

Optional arguments:

  • imin, imax, jmin, jmax, kmin, kmax : for defining spatial windows
  • opt : may be used to pass key -full (compute the mean for full steps, instead of default partial steps)

Required files: Files,, must be in the current directory (use function fixed_fields() for that; see example below).


  • main output : a netcdf file (variable : var_3D_cdfvar)

Climaf call example:: For more examples which are systematically tested, see

>>> # How to get required files for cdftools cdfmean binary
>>> fixed_fields('ccdfvar',
 ... ('',    '/data/climaf/${project}/${model}/'),
 ... ('','/data/climaf/${project}/${model}/'),
 ... ('','/data/climaf/${project}/${model}/'))
>>> duo=ds(simulation="PRE6CPLCr2alb", variable="uo", period="199807", realm="O") # some dataset, with whatever variable
>>> my_cdfvar=ccdfvar(duo,pos_grid='U')
>>> cfile(my_cdfvar) # to compute the spatial variance and get a filename with the result
>>> my_cdfvar2=ccdfvar(duo,pos_grid='U',opt='-full')
>>> cfile(my_cdfvar2)
>>> my_cdfvar3=ccdfvar(duo,pos_grid='U',imin=100,imax=102,jmin=117,jmax=118,kmin=1,kmax=2)
>>> cfile(my_cdfvar3)

Implementation: The operator is implemented as a binary using cdftools cdfmean operator.