Variable Grid possible?

Christopher Lynnes Chris.Lynnes at NASA.GOV
Thu Sep 10 11:37:15 EDT 2009


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



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