Re: [ferret_users] time axis issue / appending netcdf files

[Hein Zelle <hein.zelle@xxxxxxxxxxxxx>]

Hi Vincent,

> I would like to append two netcdf files that follow up on time, but in
> which t starting index is same:

I've had trouble with this as well.  You could try concatenating the
files with ncrcat, then re-writing the time axis manually with Ferret.
The following may work directly from Ferret (but I'm afraid it won't):

! N:M should span the whole data range
define axis /t=N:M  my_new_common_time_axis      

use data1.nc
! you may have to specify l=N:M   here as well
! N:M would be just the time range in file 1
save /file=new.nc myvar[gt=my_new_common_time_axis]

use data2.nc
! you may have to specify l=N:M   here as well
! N:M would be just the time range in file 2
save /append /file=new,nc myvar[gt=my_new_common_time_axis]


The alternative is (probably the easiest):

ncrcat file1.nc file2.nc catenated.nc

use catenated.nc     ! will probably complain about invalid time axis
define axis /t=blabla  my_new_common_time_axis   ! full time range
save /file=new.nc myvar[gt=my_new_common_time_axis@asn]


A final alternative is to try to re-write each file with ferret to a
common time axis base, then use ncrcat to concatenate them:


! repeat for each file
define axis /t=N:M  /t0="01-jan-1970"  my_new_common_time_axis
use file1.nc
save /file=file1_fixed.nc my_var[gt=my_new_common_time_axis]

! now catenate
ncrcat file*_fixed.nc  catenated_fixed.nc



Kind regards,

     Hein Zelle


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Dr. Hein Zelle
Advisor Meteorology & Oceanography

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