CDO

Hi

I would like to calculate the vorticity of the zonal and meridional velocities u and v saved on a Gaussian grid:

$ cdo sinfo test.nc
   File format : netCDF
    -1 : Institut Source   Ttype    Levels Num    Points Num Dtype : Parameter ID
     1 : unknown  Altimetry instant       1   1   1036800   1  I32  : -1            
     2 : unknown  Altimetry instant       1   1   1036800   1  I32  : -2            
   Grid coordinates :
     1 : gaussian                 : points=1036800 (1440x720)  np=0
                              lon : 0 to 359.75 by 0.25 degrees_east  circular
                              lat : 89.8088 to -89.8088 degrees_north
   Vertical coordinates :
     1 : surface                  : levels=1
   Time coordinate :  1 step
     RefTime =  1950-01-01 00:00:00  Units = days  Calendar = standard
  YYYY-MM-DD hh:mm:ss  YYYY-MM-DD hh:mm:ss  YYYY-MM-DD hh:mm:ss  YYYY-MM-DD hh:mm:ss
  1993-12-31 00:00:00

$ ncdump -h test.nc
       int u(time, lat, lon) ;
                u:standard_name = "surface_eastward_geostrophic_sea_water_velocity" ;
                u:long_name = "Absolute geostrophic velocity: zonal component" ;
                u:units = "m/s" ;
                u:grid_type = "gaussian" ;
                u:add_offset = 0. ;
                u:scale_factor = 0.0001 ;
                u:_FillValue = -2147483647 ;
                u:missing_value = -2147483647 ;

Variable v looks similar and yes, there are missing values in the data. If I run cdo uv2dv test.nc test_dv.nc, this error occurs:

cdo uv2dvl (Abort): Missing values unsupported for spectral data!

I could not find any information about that in the cdo manual or in the internet.

Thanks a lot for answer!
Chris