Variable Grid possible?

[Jennifer Adams]

That kind of data grid (with 2-dimensional coordinate variables)
doesn't fit the current gridded data model in GrADS. We have talked
about implementing a new data model, quasi-regular data, that would
fall somewhere in between regular grids and station data. But that is
not likely to be implemented any time soon. For now, interpolating to
a regular grid with PDEF is the only way to handle that kind of data
directly using GrADS.
--Jennifer

On Sep 10, 2009, at 11:37 AM, Christopher Lynnes wrote:

> Jennifer,
>   The PDEF GENERAL capability looks quite useful, but made me wonder
> if GrADS does or will support variable grids in netCDF, where the data
> are defined according to the CF-1 convention for two-dimensional
> latitude and longitude coordinate variables (http://cf-pcmdi.llnl.gov/documents/cf-conventions/1.4/cf-conventions.html#id2984605
> ).
>   We have a service to convert our AIRS swath data to netCDF files
> with this convention, which allows tools such as IDV and McIDAS-V to
> read and project them.  However, attempting an sdfopen in grads
> 2.0.a7.1 leads to the "no discernable X coordinate" error.
>   An example file can be obtained via the URL:
> http://aurapar2u.ecs.nasa.gov/airspar1/daac-bin/OTF/HTTP_services.cgi?FILENAME=%2Fdata%2Fs4pa%2FAqua_AIRS_Level2%2FAIRX2RET.005%2F2006%2F161%2FAIRS.2006.06.10.202.L2.RetStd.v5.0.14.0.G07345043455.hdf&LABEL=AIRS.2006.06.10.202.L2.RetStd.v5.0.14.0.G07345043455.nc&SHORTNAME=AIRX2RET&SERVICE=NetCDF&VERSION=1.02
>
> On Sep 10, 2009, at 7:58 AM, Jennifer Adams wrote:
>
>> You can use the PDEF GENERAL (aka PDEF FILE) option to tell GrADS
>> how to map each grid point in your 1-D vector into a 2-D lat/lon
>> grid. Please see http://www.iges.org/grads/gadoc/pdef.html
>> The example at the bottom of the page does something very similar to
>> what you'd like to do.
>> --Jennifer
>>
>> On Sep 9, 2009, at 7:03 AM, Reto Stauffer wrote:
>>
>>> Hy there
>>>
>>> I try to plot some Satellite-Data with Grads. It was "no problem"
>>> to produce a
>>> netCDF file wich i can import into GrADS and display the test-
>>> dataset.
>>>
>>> But now i have a question up to you. Normaly GrADS plots only onto
>>> a linear
>>> Grid. My netCDF-File only contains a one-line-vector with longitude
>>> and
>>> latitude boundries.
>>>
>>> Is there any possibility to import long/lat as a 2-D matrix wich
>>> discribes my
>>> own grid? I cannot found any good information about that.
>>>
>>> Test-Dataset, int [0;10] with own colormap:
>>> http://dudecom.ch/satpress/wp-content/uploads/2009/09/20090909_grads_colormapexample-543x400.png
>>>
>>> If anyone has an idea it wold be great to send me a request.
>>>
>>> Best regards
>>> Reto, Austria
>>
>> --
>> Jennifer M. Adams
>> IGES/COLA
>> 4041 Powder Mill Road, Suite 302
>> Calverton, MD 20705
>> jma at cola.iges.org
>>
>>
>>
>
> --
> Christopher Lynnes             NASA/GSFC, Code 610.2
> 301-614-5185

--
Jennifer M. Adams
IGES/COLA
4041 Powder Mill Road, Suite 302
Calverton, MD 20705
jma at cola.iges.org



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