[ncl-talk] Save output as a NetCDF or tiff file

[Dennis Shea]

By netCDF definition, a coordinate variable must be one-dimensional:

The XLAT, XLONG variables are three dimensional.

Time | 24] x [south_north | 229] x [west_east | 219]

As with the WRF files, these must be written as regular variables.

     ncdf->XLAT     = XLAT
     ncdf->XLONG = XLONG

Most commonly, the XLAT/XLONG variables do not vary with time. Hence some
users just write the initial values as a two-dimensional variable

     ncdf->XLAT     = XLAT(0,:,:)
     ncdf->XLONG = XLONG(0,:,:)



On Mon, Nov 13, 2023 at 1:21 AM Setareh Rahimi <setareh.rahimi at gmail.com>
wrote:

> Thanks Dennis, but the page is not available!
>
> On Mon, Nov 13, 2023 at 2:58 AM Dennis Shea <shea at ucar.edu> wrote:
>
>> See copy_VarCoords
>>
>> On Fri, Nov 10, 2023 at 1:39 PM Setareh Rahimi <setareh.rahimi at gmail.com>
>> wrote:
>>
>>> Thank you so much for your help. How can I assign lat/lon to the AOD,
>>> please?
>>> I used the below lines in the script but received the following error: " fatal:(XLAT)
>>> is not a named dimension in variable (a2)".
>>>
>>>
>>>
>>>        system("/bin/rm -f AOD550_2D.nc")    ; remove any pre-existing
>>> file
>>>
>>>        ncdf = addfile("AOD550_2D.nc" ,"c")  ; open output netCDF file
>>>
>>>
>>>     ;===================================================================
>>>
>>>     ; create global attributes of the file (optional)
>>>
>>>     ;===================================================================
>>>
>>>        fAtt               = True            ; assign file attributes
>>>
>>>        fAtt at title         = "Derived AOD"
>>>
>>>        fAtt at creation_date = systemfunc ("date")
>>>
>>>
>>>        fileattdef( ncdf, fAtt )            ; copy file attributes
>>>
>>>
>>>     ;===================================================================
>>>
>>>     ; make time an UNLIMITED dimension; recommended  for most
>>> applications
>>>
>>>     ;===================================================================
>>>
>>>        filedimdef(ncdf,"time",-1,True)
>>>
>>>
>>>     ;===================================================================
>>>
>>>     ; output variables directly; NCL will call appropriate functions
>>>
>>>     ; to write the meta data associated with each variable
>>>
>>>     ;===================================================================
>>>
>>>        ncdf->AOD550_2D  = AOD550_2D
>>>
>>>
>>>       ncdf->a2  = a2(0,:,:,:)
>>>
>>>       AOD550_2D!0    = "lat"
>>>
>>>       AOD550_2D!1    = "lon"
>>>
>>>              AOD550_2D&lat  = a2&XLAT
>>>
>>> ===========================================================================================
>>> here is printVarSummary of "a2"
>>>
>>> Variable: a2
>>>
>>> Type: float
>>>
>>> Total Size: 144434880 bytes
>>>
>>>             36108720 values
>>>
>>> Number of Dimensions: 4
>>>
>>> Dimensions and sizes: [Time | 24] x [bottom_top | 30] x [south_north |
>>> 229] x [west_east | 219]
>>>
>>> Coordinates:
>>>
>>>             Time: [   0..  23]
>>>
>>> Number Of Attributes: 6
>>>
>>>   coordinates : XLONG XLAT XTIME
>>>
>>>   stagger :
>>>
>>>   units : ?
>>>
>>>   description : bin 2 layer optical thickness
>>>
>>>   MemoryOrder : XYZ
>>>
>>>   FieldType : 104
>>>
>>>
>>>
>>> On Fri, Nov 10, 2023 at 8:17 PM Dennis Shea <shea at ucar.edu> wrote:
>>>
>>>> netCDF operator  'ncks' to extract a variable from a netCDF file and
>>>> copy it to another
>>>>
>>>> %> ncks -v xxx Model.nc XXX.nc
>>>>
>>>> where 'xxx' is the name of the variable on the model file
>>>> ===============================
>>>>     AOD
>>>>
>>>>        *system* <https://www.ncl.ucar.edu/Document/Functions/Built-in/system.shtml>("/bin/rm -f AOD.nc")    ; remove any pre-existing file
>>>>        ncdf = *addfile* <https://www.ncl.ucar.edu/Document/Functions/Built-in/addfile.shtml>("AOD.nc" ,"c")  ; open output netCDF file
>>>>
>>>>     ;===================================================================
>>>>     ; create global attributes of the file (optional)
>>>>     ;===================================================================
>>>>        fAtt               = True            ; assign file attributes
>>>>        fAtt at title         = "Derived AOD"
>>>>        fAtt at creation_date = *systemfunc* <https://www.ncl.ucar.edu/Document/Functions/Built-in/systemfunc.shtml> ("date")
>>>>        *fileattdef* <https://www.ncl.ucar.edu/Document/Functions/Built-in/fileattdef.shtml>( ncdf, fAtt )            ; copy file attributes
>>>>
>>>>     ;===================================================================
>>>>     ; make time an UNLIMITED dimension; recommended  for most applications
>>>>     ;===================================================================
>>>>        *filedimdef* <https://www.ncl.ucar.edu/Document/Functions/Built-in/filedimdef.shtml>(ncdf,"time",-1,True)
>>>>
>>>>     ;===================================================================
>>>>     ; output variables directly; NCL will call appropriate functions
>>>>     ; to write the meta data associated with each variable
>>>>     ;===================================================================
>>>>        ncdf->AOD  = AOD
>>>>
>>>> ================================
>>>> See
>>>> *https://www.ncl.ucar.edu/Applications/method_1.shtml
>>>> <https://www.ncl.ucar.edu/Applications/method_1.shtml>*
>>>>
>>>> On Fri, Nov 10, 2023 at 1:02 AM Setareh Rahimi via ncl-talk <
>>>> ncl-talk at mailman.ucar.edu> wrote:
>>>>
>>>>> Dear all,
>>>>> I have calculated Aerosol Optical Depth (AOD) from WRF-Chem output
>>>>> using "TAUAER2" and "TAUAER3" variables (script attached). Instead of using
>>>>> the created AOD to plot it, I would like to save the AOD as a NetCDF or
>>>>> tiff file. So how can I do this, please?
>>>>> I have another question. How can I extract one variable from the model
>>>>> output and save it as a NetCDF or tiff file?
>>>>> Please help me with these issues.
>>>>> Kind regards,
>>>>>
>>>>> --
>>>>> S.Rahimi
>>>>>
>>>>> _______________________________________________
>>>>> ncl-talk mailing list
>>>>> ncl-talk at mailman.ucar.edu
>>>>> List instructions, subscriber options, unsubscribe:
>>>>> https://mailman.ucar.edu/mailman/listinfo/ncl-talk
>>>>>
>>>>
>>>
>>> --
>>> S.Rahimi
>>>
>>>
>
> --
> S.Rahimi
>
>
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