Pooran,
Error codes for the fortran 90 interface are missing from the netCDF
on-line documentation. You can look them up in the library source code
here:
https://github.com/Unidata/netcdf-fortran/blob/master/fortran/netcdf_constants.f90
The code for "attribute not found" is "nf90_enotatt". Always use the
symbolic name in your code, never the numeric value. Since you are new to
using fortran, I will also mention that you must declare "use netcdf" at
the top of each program or subroutine that directly accesses any part of
the netCDF fortran 90 interface.
--Dave
On Mon, Apr 15, 2019 at 9:56 AM Dave Allured - NOAA Affiliate <
dave.allured@xxxxxxxx> wrote:
> Pooran,
>
> It looks like your user function cf90_get_att is ignoring the netCDF
> function status code. You need to add some code to check for the existence
> of scale_factor and add_offset attributes. An easy way to do this is to
> call nf90_get_att and check the returned netCDF status code. There is a
> specific error code for "attribute does not exist". See documentation for
> that function.
>
> Use the status information to automatically decide how to handle scale and
> offset corrections, as Daniel described.
>
> --Dave
>
>
> On Mon, Apr 15, 2019 at 9:15 AM Daniel Neumann <
> daniel.neumann@xxxxxxxxxxxxxxxxx> wrote:
>
>> Dear Pooran,
>>
>> the scale_factor and add_offset attributes are optional. They are used
>> for packing data (search for "netcdf packing data" for details) and for
>> similar purposes. If they do not exist, you can consider scale_factor to be
>> 1.0 and add_offset 0.0 (or you just ignore them and use the data as they
>> are).
>>
>> Cheers,
>> Daniel
>>
>>
>> On 15.04.19 07:02, Pooran khedri wrote:
>>
>> Hi everybody,
>> I have a piece of a code to read meteorological forcing from ECMWF
>> database in a NetCDF format, Here is some of my piece code to read this
>> file
>>
>> !reading atmospheric pressure
>>
>> CALL cf90_get_att(iunit, atmpID, "scale_factor", scale_factor)
>> CALL cf90_get_att(iunit, atmpID, "add_offset", offset)
>> CALL cf90_get_var(iunit, atmpID, atmpindat(:,:), filepars%timerec)
>> atmpindat = atmpindat*scale_factor + offset
>>
>> but I have downloaded the new meteorological file from another database
>> in a NetCDF format , this new file is different from ECMWF file and it does
>> not have add_offset and scale_factor in its attribute and my code does
>> not read it and I have got many errors.
>> I think I have to add the add_offset and scale_factor to the new
>> NetCDF file or I have to modify the FORTRAN code that scaling is not
>> used for this variable, but I do not know how to do them☺ ,I am new to
>> using the NetCDF files and FORTRAN .
>> I would be grateful if you could explain to me How to solve my problem.
>>
>> Pooran
>>
>>
