[gradsusr] netcdf point (station) datasets in grads

Ghansham Sangar ghanshamsangar at gmail.com
Wed Oct 30 12:59:19 EDT 2013


I have another query related to satellite data.
I have geostationary satellite data with 2-dimensional lat/lon coordinate
variables with cold space included where lat/lon values are undefined
(pretty much expected). How do we handle such datasets in grads. I am
following cf conventions for gridded data here. I hope I am able to
communicate properly.

Regards
ghansham

On Wednesday, October 30, 2013, James T. Potemra wrote:

>
> Sorry if I misread the initial question, but you're right having multiple
> stations in a single file will not work.  On the other hand if you have a
> single station in a single file, and this file is CF-1.6, you can access
> this via GrADS with an appropriate control file.  And yes, IDV can
> recognize the new CF-1.6 discrete geometry, but other client tools may need
> a work-around for the missing lat/lon dimensions.
>
> Jim
>
> On 10/30/13 2:18 AM, Jennifer Adams wrote:
>
> There is no interface in GrADS for handling station data in netcdf format.
> There has been no demand or need for it because no standard existed for
> representing station data with the netcdf data/metadata framework. The CF
> discrete sampling geometry convention was put forward by Unidata in order
> to establish a standard for the community, but data providers and software
> developers have not rushed to adopt/implement this standard. That sort of
> effort generally requires dedicated funding. Unidata is doing its part by
> supporting the convention in the netcdf java library and in IDV. If you
> want to look at this data with GrADS, you will have to write some external
> code to convert it to the GrADS station data format.
>
>  In some cases, you can try to map your station data into the gridded
> data interface in GrADS, but that is awkward -- X becomes the dimension for
> station id, lat and lon become data variables, and you cannot display an
> aggregation of stations in lat/lon space. The relative success of this
> strategy would depend on the way the metadata is presented in your data
> file.
>
>  --Jennifer
>
>
>  On Oct 29, 2013, at 1:47 PM, Ghansham Sangar wrote:
>
> R/Sir
> Is it possible to open point datasets in netcdf format following CF
> conventions (see discrete sampling geometry in cf metedata conventions1.6
> document available online). I could not find online documentation regarding
> same. I am using grads 2.0.2. The dataset is satellite derived wind vectors
> having relevant fields (ucomp,  vcomp, wind speed, Windows direction,
> latitude, longitude,  date/time of each observation).
> Ghansham
>
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