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[IDV #JRS-727215]: Rotated regular Lat Lon grids

Hi Breo-

Thanks for testing this.  I'm going to move this over to the grib support staff 
to look
into.  I'm sure the dx,dy of 0 is causing some problems.  I also see an issue 
with
the time range indicator not being recognized:

PDS: Time Range Indicator 13 is not yet supported

You should be hearing from them soon.

Thanks for the sample files.

Don

> I've tried to open the COSMO files with the beta version 2.7b3 and the
> result is the same as with the version 2.6r2. IDV is able to list the
> variables but not able to plot any field. To this mail I've have
> attached you two files from two different COSMO model grid with a
> single Tsfc field.
> 
> cosmo_lme_tsfc.grib: This covers all european continent
> cosmo_lmk_tsfc.grib: Higher resolution grid over Germany
> 
> The is something regarding this files that may be important. When
> reading the ouput of the command "wgrib -V file", you will noticed that
> fields "dx" and "dy" are equal to "0". The reason for this is that GRIB
> coding only allows for 3 digit decimals and the smallest domain has a
> resolution of 0.0000. The modeling section has decided to specify the
> resolution with two opposite corners of the model grid and the number
> of points ((latmax-latmin)/(Ny-1)), and leave "dx" and "dy" fields to
> "0". There is an specific bit in the grib description section (GDS 9,
> BIT 7) that accounts for this. It should be "1" when you want to
> specify the resolution in this indirect way.
> 
> Here is the piece of the code from our models that checks for this bit
> and calculates the resolution in case is not specified.
> 
> ------------------------------------------------------------------------------------>
>     ! igds is an integer array for the grid description section
> 
> 
>     ! Check, whether the resolutions are given or not
> 
>     IF (IBITS(igds(9),7,1) /= 0) THEN
> 
>       zdlat_grib   = REAL(igds(13), ireals)*0.001_ireals
> 
>       zdlon_grib   = REAL(igds(12), ireals)*0.001_ireals
> 
>     ELSE
> 
>       zdlat_grib   = REAL(igds(10)-igds( 7), ireals)*0.001_ireals /
> (jedim-1)
> 
>       IF (igds(11)-igds( 8) < 0.0_ireals) THEN
> 
>         ! If the area is located around the 180-Meridian,
> igds(11)-igds(8)
> 
>         ! will be negative and 360 degrees have to be added
> 
>         zdlon_grib   = (REAL(igds(11)-igds( 8), ireals)*0.001_ireals
> +    &
> 
>                        360.0_ireals) / (iedim-1)
> 
>       ELSE
> 
>         zdlon_grib   = REAL(igds(11)-igds( 8), ireals)*0.001_ireals /
> (iedim-1)
> 
>       ENDIF
> 
>     ENDIF
> 
> ------------------------------------------------------------------------------------>
> 
> I don't know if this may be important or not but, just in case, I've
> preferred to include it.
> 
> I hope this will be useful for you.
> 
> All the best.
> 
> Breo
> 
> 
> Unidata IDV Support wrote:
> 
> Hi Breogan-
> 
> 
> 
> My name is Breogan Gomez and I am currently working in the data
> assimilation section of the DWD (German Weather service). I have
> recently started to play around with the IDV and its advanced features
> but our models have particular grids that are not contemplated in this
> software.
> 
> This is the case of our local model, COSMO, that uses a rotated regular
> lat/lon grid (equivalent to the GFS grid but with the north pole in a
> different place). The output format is GRIB1.
> 
> I have tried to open the file and IDV is able to recognize the inventory
> of the file, but is no able to plot the fields. Do you know if this type
> of grid is available for ploting?
> 
> 
> 
> Which version of the IDV are you using?  There were some fixes made recently 
> for the
> rotated lat/lon grids made in the underlying grib decoding software.  If it 
> does not
> work with the latest beta version (2.7b3):
> 
> http://www.unidata.ucar.edu/downloads/idv/test
> 
> please upload a sample file to:
> 
> http://motherlode.ucar.edu/repository/alias/idvupload
> 
> and we'll look into this.
> 
> Don Murray
> 
> Ticket Details
> ===================
> Ticket ID: JRS-727215
> Department: Support IDV
> Priority: Normal
> Status: Open
> 
> 
> 
> 
> 
> 
> 
> 


Ticket Details
===================
Ticket ID: JRS-727215
Department: Support netCDF Java
Priority: Normal
Status: Open