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[GEMPAK #ASD-921184]: Ensemble Functions

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  • Subject: [GEMPAK #ASD-921184]: Ensemble Functions
  • Date: Thu, 21 Sep 2006 11:01:18 -0600
James,

The ENS_ functions described in the GFUNC help pages use the GDFILE={} syntax to
reference files for the ensemble functions.

Here is one way to use this functionality:

1) Decode the individual ensemble members to separate files so that the
parameters can be decoded without the PDS extension (eg nagrib PDSEXT=no). 
Eg, you want all members named HGHT. To decode them into a single file, you 
would
want to use the PDS extension for unique names (eg HGHTC001, HGHTP001, etc),
but then those names won't match the function name in your GDPFUN.

As a file naming example, my $MODEL/ens directory has 24 hour forecast files:
gec00_2006092100f024.gem
gep01_2006092100f024.gem
gep02_2006092100f024.gem
gep03_2006092100f024.gem
gep04_2006092100f024.gem
gep05_2006092100f024.gem
gep06_2006092100f024.gem
gep07_2006092100f024.gem
gep08_2006092100f024.gem
gep09_2006092100f024.gem
gep10_2006092100f024.gem

These follow the control and perturbation ge[cp]?? as the ftpprd.ncep.noaa.gov 
server
has (eg data/nccf/com/gens/prod/gefs.20060921/00/pgrb2a). I'm using these since 
it is what will be
added to the CONDUIT data feed in the upcoming week.

My datatype.tbl file has:
! NCEP Global ensemble members
GEFS         $MODEL/ens                gep*_YYYYMMDDHHfFFF.gem .....

In gdplot2, I can plot the 24 hour ensemble average of the 500 mb HGHT 
perturbation fields with:
 GDFILE   = {gefs}
 GDATTIM  = 0000f024
 GLEVEL   = 500
 GVCORD   = pres
 GDPFUN   = ens_savg(hght)

The GDFILE = {gefs} uses the set of files that would be referred to 
individually as
gefs:01, gefs:02, gefs:03, gefs:04.....

The :## in the GDFILE name is what will replace the "*" character in the 
datatype.tbl template.

Steve Chiswell
Unidata User Support



> Hi,
> 
> I'm trying to create plots of GFS ensemble mean 500mb hghts(individually
> for each model forecast time). The description for gparm indicates using
> "ens_savg(scalar variable)" to accomplish this. However, when I attempt
> via a program such as gdplot2,  I get errors of
> 
> [DE -5]  No ensemble file referenced in ensemble diagnostic.
> [DG -70]  Ensemble field cannot be computed.
> [GDPLOT 2]  The requested scalar/vector cannot be computed.
> 
> I set GDPFUN   = ENS_SAVG(HGHT)
> 
> I've obviously mis-interpreted the help explanation, and would
> appreciate help in what I need to input correctly.
> 
> James
> 
> --
> ----------------------------------------------
> James Murakami
> Staff Meteorologist/Student Affairs
> Department of Atmospheric and Oceanic Sciences
> University of California, Los Angeles
> 405 Hilgard Ave.
> Los Angeles, CA  90095-1565
> 
> 
> e-mail:  address@hidden
> telephone:  310-825-2418
> Fax:  310-206-5219
> -----------------------------------------------
> 
> 


Ticket Details
===================
Ticket ID: ASD-921184
Department: Support GEMPAK
Priority: Normal
Status: Closed