Re: grib reading in IDV

Hi Brian-

We were tied up in the IDV training workshop the past two days,
so sorry for the delay in responding.

Brian Blanton wrote:

I have unstructured (i.e. finite element) ocean model output that I format
in GRiB on a regular grid for quick visualization.

When stuffing the GRiB into IDV, I notice that IDV does not like the center=0 specification (grib1 pds octet # 5). So, I chose "center=3", which is an un-used
center designation, as far as the NCEP Office Note 388 is concerned.
IDV doesn't like that either.

I'm a bit reluctant to use center=7, since that's NCEP's designation,
and these are definitely not NCEP files.

The java error, with center=0,  is :
NotSupportedException : ucar.grib.NotSupportedException: table for center: 0 subCenter: 0 number: 2
ERROR: An error has occurred:
There was an error loading the data:

So, since I know zip about jar files, and zip about java for that matter,
can you tell me where to edit the java code to get around this?
I can probably figure out what to do (in java, to insert the needed table),
but I have no idea where to look in the jar files.

Thanks very much,
and IDV is really interesting and VERY useful. We are using it as a viz system for
a hurricane storm-surge project to viz the hurricane wind fields and the
ocean's water level response (storm surge).

If you are using the 1.2RC1 (or later) release, you can specify
pointers to your own grib tables without having to write code.
This will be documented in the 1.2 release.

The IDV will look for a file named "grib1lookuptable.lst" in
your IDV resources directories (user path, site path, application
path).  The user path is typically located in the
.metapps/DefaultIdv directory of your home directory.

The format of this file would be:

center: subcenter:  table_id:  param_table_location

a -1 will match all (for subcenter, table_id).  The default
location for tables is /resources/grib/tables and the default
NCEP parameter list is nceptab_2.tab.

So, for your particular situation, you could create
the table that looks like:

3:-1:-1:/resources/grib/tables/nceptab_2.tab

to point to the one in the distribution.

If you need to create your own parameter table, you can
point to that (paths are relative to the location of the
grib1lookuptable.lst).  The format of the parameter table is:

        NUMBER:NAME:DESCRIPTION [UNIT]

(wgrib format)

So, for example, the NCEP table looks like:

0:var0:undefined
1:PRES:Pressure [Pa]
2:PRMSL:Pressure reduced to MSL [Pa]
3:PTEND:Pressure tendency [Pa/s]
4:PVORT:Pot. vorticity [km^2/kg/s]
5:ICAHT:ICAO Standard Atmosphere Reference Height [M]
6:GP:Geopotential [m^2/s^2]
7:HGT:Geopotential height [gpm]
8:DIST:Geometric height [m]
9:HSTDV:Std dev of height [m]
10:TOZNE:Total ozone [Dobson]
11:TMP:Temperature [K]
12:VTMP:Virtual temperature [K]
13:POT:Potential temperature [K]
14:EPOT:Pseudo-adiabatic pot. temperature [K]
15:TMAX:Max. temperature [K]
16:TMIN:Min. temperature [K]
17:DPT:Dew point temperature [K]
18:DEPR:Dew point depression [K]
......

Let me know if you have any problems with this.

Don
*************************************************************
Don Murray                               UCAR Unidata Program
dmurray@xxxxxxxxxxxxxxxx                        P.O. Box 3000
(303) 497-8628                              Boulder, CO 80307
http://www.unidata.ucar.edu/staff/donm
        "Time makes everyone interesting, even YOU!"
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