[ncl-talk] Convert unpacked netCDF file to packed one

[Setareh Rahimi]

Dear Dave,
Many thanks for your help and advice. And, appreciate the time you consider
to guide me.
Best wishes,

On Mon, Jan 11, 2021 at 11:15 PM Dave Allured - NOAA Affiliate <
dave.allured at noaa.gov> wrote:

> I see.  I suggest the best solution would be a simple upgrade to the model
> code, so that it could read both packed and unpacked air temp files.  This
> will enable the model to use future data updates without extra processing.
>
> In fortran, this would be an if statement to check whether there is a
> scale_factor attribute.  If not, then skip reading scale_factor and
> add_offset, also skip the unpacking statement or loop that converts packed
> data values to unpacked.  Just read in the unpacked values directly.  You
> would need two read statements, the original one for the packed data type,
> and a new one for the unpacked data type (fortran real).
>
> If something prevents you from changing the model code, then just convert
> the air temp file to packed using the NCL *pack_values* function.  See
> the general documentation for how to read and write a netcdf file.
>
>
> On Mon, Jan 11, 2021 at 12:00 PM Setareh Rahimi <setareh.rahimi at gmail.com>
> wrote:
>
>> Dear Dave,
>> Thank you for your reply. Yes I am sure, because the model I am running
>> only accept packed nc file with scale factor.
>> Please have a look at attached file showing the error I face while
>> running the model with mentioned nc file.
>> Best regard
>>
>> On Mon, Jan 11, 2021 at 22:20 Dave Allured - NOAA Affiliate <
>> dave.allured at noaa.gov> wrote:
>>
>>> That file is already compressed to 31% of its natural array size, using
>>> netcdf-4 internal compression.  Are you sure you want to do that?  If yes,
>>> then use the NCL function *pack_values*.
>>>
>>>
>>> On Mon, Jan 11, 2021 at 11:07 AM Setareh Rahimi via ncl-talk <
>>> ncl-talk at mailman.ucar.edu> wrote:
>>>
>>>> Dear all,
>>>> I need to convert an unpacked netCDF file to a packed one (
>>>> ftp://ftp2.psl.noaa.gov/Datasets/ncep.reanalysis2/pressure/air.2019.nc),
>>>> I wonder if this possible using NCL?
>>>> Many thanks in advance,
>>>> Best wishes,
>>>> --
>>>> S.Rahimi
>>>>
>>>

-- 
S.Rahimi
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