Does Grads support 5D data?

[Jennifer Adams]

On Dec 10, 2007, at 12:19 PM, Wenli Yang wrote:

> Hello,
>
> Does Grads support 5D data?  I saw Jennifer and some other people
> were discussing 5D data in grads about a year ago (http://
> www.cgd.ucar.edu/pipermail/cf-metadata/2006/001207.html).
The support for 5D grids is in version 2.0, soon to be available as
an alpha release.

> We produced some 5D data in CF-netCDF in the following dimension
> order: Orbit * Time * Pressure * Latitude * Longitude
> where the orbit dimension records number of satellite orbits the
> data may contain, ranging from 1 to 14, and Time and Pressure are
> mostly just one, such as the following: 10 * 1 * 1 * 180 * 360.
> We correctly named T/Z/Y/X for the last for dimensions and didn't
> set the "axis" attribute to the first "orbit" dimension.  We seem
> not be able to display such data in Grads.  I am not sure if it's
> our data problem or Grads still does not support 5D.
You could look at this data with version 1.9 by putting non-negative
integers array indices in the units field of the variable
declaration. From the docs:

If your data file contains a variable that also varies in a non-world-
coordinate dimension (e.g. histogram interval, spectral band,
ensemble number) then you can put a non-negative integer in the list
of varying dimensions that will become the array index of the extra
dimension. For example:

       VAR=>hist0   0   0,y,x   First historgram interval for VAR
       VAR=>hist1   0   1,y,x   Second historgram interval for VAR
       VAR=>hist2   0   2,y,x   Third histogram interval for VAR

I have not tested this option with 5D data, I don't think it will
work if VAR also varies in Z and T.


>
> A more general question is perhaps: does Grads support high
> dimensional data in the following form:
>   D1 * D2 * ... Dn * T * Z * Y * X
GrADS has a 4D (soon to be 5D) environment for grids -- it won't read
data with more dimensions than that. HDF is a more general format,
doesn't limit the number of dimensions an array can have. GrADS can
handle some, but not all, HDF gridded files.

>
> I use HDFview to display multidimensional HDF data.  HDFView allows
> users to specify which dimension is horizontal, vertical, etc.  Can
> this also be done in Grads?
>
> Many Thanks,
>
> Wenli Yang

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



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