How do I add a dimension to a netCDF?

[Mark A Ohrenschall <Mark.A.Ohrenschall@xxxxxxxx>]

Hello,

I have a netCDF file with this description:

[mao@panther dods]$ ncdump -h ims2003097.cdf
netcdf ims2003097 {
dimensions:
        cols = 2500 ;
        rows = 1250 ;
variables:
        float MyData(rows, cols) ;
                MyData:TITLE = "ims2003097" ;
}
I'd like to add cols and rows coordinate variables, plus a time dimension
(with one element) and make MyData a 3-D grid. I tried this in ferret:
yes? use ims2003097.cdf
yes? define axis/x=-179.856:179.856/npoints=2500 cols
yes? define axis/y=89.856:-89.856/npoints=1250 rows
yes? define axis/t=12149:12149:1/npoints=1/units=days time
yes? save/file=ims2003097.nc/clobber mydata[GX=cols,GY=rows,GT=time]
 LISTing to file ims2003097.nc
yes?
resulting in this netCDF file description:
[mao@panther dods]$ ncdump -h ims2003097.nc
netcdf ims2003097 {
dimensions:
        COLS = 2500 ;
        ROWS = 1250 ;
variables:
        double COLS(COLS) ;
                COLS:point_spacing = "even" ;
        double ROWS(ROWS) ;
                ROWS:point_spacing = "even" ;
        float MYDATA(ROWS, COLS) ;
                MYDATA:missing_value = -1.e+34f ;
                MYDATA:_FillValue = -1.e+34f ;
                MYDATA:long_name = "MYDATA" ;
                MYDATA:long_name_mod = "regrid: 0.14 delta on X, 0.14 delta on Y" ;
                MYDATA:history = "From ims2003097" ;

// global attributes:
                :history = "FERRET V5.40   28-May-03" ;
}
So I created the cols and rows coordinate variables just fine, but failed
to add a time coordinate variable and make MYDATA a 3-D grid.

How do I do this?

Thanks in advance,

Mark