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Re: axis order when useing SAVE?
Hi Crystal,
This is a non-standard netCDF file. The coordinate axes (dimensions) in
a netcdf file must have unique names. If the file does not have enough
information or encounters non-standard axis ordering, then Ferret will
use the dimensions in the order in which they are encountered. This
lets you open and look at files which do not meet the standards and
perhaps fix them.
The CF conventions that Ferret adheres to for reading NetCDF files is at
http://www.cgd.ucar.edu/cms/eaton/cf-metadata/CF-1.0.html
And the description of coordinate variables and grids can be found at
http://www.cgd.ucar.edu/cms/eaton/cf-metadata/CF-1.0.html#grids
To see what Ferret is doing with the SAVE statements, look at the header
information of your NetCDF file with ncdump -h.
yes? save/file=my_file.nc Var_a
yes? spawn ncdump -h my_file.nc
! are you redefining axis abc here?
yes? save/append/file=my_file.nc Var_b
yes? spawn ncdump -h my_file.nc
I think you'll see that coordinate variable abc keeps the direction it
had when the file is first written. I would suggest using unique names
for the axes within Ferret, and if you want to change the names for use
in another application, then you could edit the file using NCO operators
after exiting Ferret.
Ansley
Gene-Hua Crystal Ng wrote:
Hi,
How can I save 2 variables to a netCDF file that have grids with the same
axis describing two different axes (e.g. x and y axis)?
For example, I have Var_a defined on a grid with "abc" as the X axis.
I also have Var_b defined on a grid with "abc" as the Y axis. I then use
the following to try to save both to file:
save/file=my_file.nc Var_a
save/append/file=my_file.nc Var_b
Ferret allows me to do this without any error message. However, when I
then try to USE my_file.nc, I get the following message:
*** NOTE: unsupported ordering of axes in variable VAR_B
*** NOTE: The default ordering will be used
When I then look at the data in the file with ferret, everything looks
fine, but I know something isn't right because the model I'm trying to
input the data file to (CLM) gives an error when trying to read the file.
I tried using the command qualifier /order=y with SAVE but am not having
any luck.
Thanks,
Crystal
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