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[IDV #FOS-898337]: IDV - netcdf CF1.0 - vertical grid system

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  • Subject: [IDV #FOS-898337]: IDV - netcdf CF1.0 - vertical grid system
  • Date: Tue, 24 Apr 2007 09:58:27 -0600
Hi Guido-

> Institution: cesi ricerca
> Package Version: 2.0
> Operating System: win 2000
> Hardware Information: pentium 4
> Inquiry: Dear support team,
> I'm trying to manage netCDF files derived from CAMx chemical transport model.
> Depending on the meteorological driver (RAMS or MM5/WRF) the vertical 
> coordinate
> system can be defined -following CF1.0 convention- in two ways:
> "atmosphere_hybrid_height_coordinate" to replicate RAMS sigma-z or
> "atmosphere_sigma_coordinate" to replicate MM5/WRF grid system.
> ...I've troubles in both cases...
> - with RAMS sigma-z, IDV displays "flat" horizontal slices, while they should 
> be "terrain following"
> - With MM5 sigma levels IDV correctly displays a "terrain following" grid 
> structure, but
> it fails when I try to create cross sections, vertical profiles or 
> time-height sections

Thanks for these test cases.  They have uncovered several issues 
with both the IDV and the underlying netCDF-Java library.  The
good news is that we have been able to fix most of them.

Here is a rundown of the issues:

- Versions of IDV after 2.0 no longer worked  on the 
atmosphere_sigma_coordinate when there was a time dimension.
This has been fixed in the latest development version of 
netCDF-Java and the nightly build of the IDV.

- There is currently no support for the "atmosphere_hybrid_height_coordinate"
in the netCDF-Java or IDV.  I'm in the process of adding support
for this, but am not sure when that will be available in the
nightly build. 

- There was a problem doing cross sections through grids
with dimensionless vertical coordinates.  This has been fixed and
is in the latest nightly build of the IDV.

- There was a problem displaying the cross section selector with
the MM5 sigma grid,  which has been fixed in the nightly release.

> In attach there are a couple of files written with both vertical grid systems.
> 
> P.s. errors seem not to be depending on horizontal grid system...
> 
> many thanks in advance for your attention
> With the best regards

If you want to check out the status so far, you can download
the nightly build from:

http://www.unidata.ucar.edu/software/idv/release/nightly

The outstanding issue is support for the atmosphere_hybrid_height_coordinate
which we should have a fix for in the next couple of days.

Don

Ticket Details
===================
Ticket ID: FOS-898337
Department: Support IDV
Priority: Urgent
Status: Open