[gradsusr] handling non-world coordinates

[Jeff Duda]

Jennifer,
Thank you for the reply.  I had tried something very similar to that, but
it didn't work.  Now I can't remember what that was.  Regardless, it works
now.

Thanks!

Jeff

On Wed, Sep 24, 2014 at 6:56 AM, Jennifer Adams <jma at cola.iges.org> wrote:

> Hi, Jeff —
> Your data file has 4 dimensions, so you can map your data’s dimensions to
> the world coordinate grid dimensions and not worry about putting array
> indices in your variable declarations. May I suggest the following:
>
> xdef 803 linear 1 1
> ydef 603 linear 1 1
> zdef 5 linear 1 1
> edef 3 names 1 2 3
> tdef 1 linear 01jan0001 1mo
> vars 2
> forecast_PoP=>fcst  5  e,z,y,x  forecast PoP
> observed_PoP=>obs 5  z,y,x  observed PoP
> endvars
>
> It is more confusing to use T for a dimension that isn’t really a time
> coordinate, so I have left that one unused, with a default time and a size
> of 1.
> —Jennifer
>
>
>
> On Sep 23, 2014, at 11:42 AM, Jeff Duda <jeffduda319 at gmail.com> wrote:
>
> Hello,
> I have some netCDF files that I created using my own FORTRAN code.  I wish
> to display some arrays in those files that have some non-world-coordinate
> dimensions.  For example, my data contain probabilities of precipitation
> from three different ensembles using five different precipitation
> accumulation thresholds.  Therefore, I have two non-world-coordinate
> dimensions.  I see in the documentation how to handle one (see below):
>
> *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 *
>
> *Another option in this example would be to fill the unused Z axis with
> the histogram intervals: *
>
>
>
> * zdef 3 linear 1 1 ... VAR=>hist   3   z,y,x   VAR Histogram*
>
> *In this case, it would appear to GrADS that variable 'hist' varies in Z,
> but the user would have to remember that the Z levels correspond to
> histogram intervals. The latter technique makes it easier to slice through
> the data, but is not the most accurate representation. And if you don't
> have an unsued world-coordinate axis available, then you still have a way
> to access your data.*
> However, I am unsure of how to handle two.  Let alone, if you have no
> "free" world coordinates, how do you reference these other dimensions when
> displaying the grids in Grads?
>
> Here is an ncdump of one of my files:
>
> netcdf \0527_neighborhood_PoP_007200 {
> dimensions:
>         X = 803 ;
>         Y = 603 ;
>         threshold = 5 ;
>         ensemble = 3 ;
> variables:
>         float forecast_PoP(ensemble, threshold, Y, X) ;
>         float observed_PoP(threshold, Y, X) ;
> }
>
> Jeff Duda
> --
> Jeff Duda
> Graduate research assistant
> University of Oklahoma School of Meteorology
> Center for Analysis and Prediction of Storms
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>
> --
> Jennifer M. Adams
> Center for Ocean-Land-Atmosphere Studies (COLA)
> 111 Research Hall, Mail Stop 2B3
> George Mason University
> 4400 University Drive
> Fairfax, VA 22030
>
>
>
>
>
>
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>


-- 
Jeff Duda
Graduate research assistant
University of Oklahoma School of Meteorology
Center for Analysis and Prediction of Storms
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