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20020618: Garp

>From: Pavel Byles-Howard University Engineering <address@hidden>
>Organization: UCAR/Unidata
>Keywords: 200206181903.g5IJ34611529

>Steve:
>Do I have to download the LDM-McIDAS decoder to view *.wmo data coming in 
>from the ldm data download?
>And how do I let Garp view the data? For example if I wanted to view 
>satellite data would I set the dir to .../Gempak/gempak/data/images/sat?
>
>If not how then?
>Thanx
>
>-- 
>Pavel Byles
>Sent using Pine ver. 4.4
>on RedHat Linux 7.3
>http://138.238.177.225
>

Pavel,

The only programs you would need from the  ldm-mcidas decoders package are
pnga2area and pngg2area. These are used to uncompress the satellite imagery
in the MCIDAS data feed. Examples of pqact.conf actions for the LDM are shown:
http://www.unidata.ucar.edu/packages/gempak/tutorial/pqact/images.tbl

Typically, if your LDM was installed in ~ldm, then you have a ~ldm/data
directory where your ldm.pq lives. For ease of use, I generally
assume that your GEMDATA directory will be the data/gempak directory
under your ~ldm account (you can replace ~ldm with wherever
the LDMHOME directory on your system is).

You can define GEMDATA in the Gemenviron script. The satellite data is 
defined by the $SAT environmental variable in Gemenviron, and is set to
be $GEMDATA/images/sat. So, create your ~ldm/data/gempak/images/sat
directory and, from the web page examples I mentioned above, 
to store the GOES Visible imagery, you would use a pqact.conf line
such as:
MCIDAS  ^pnga2area Q1 (U[^ACXY1]) (.*) (.*)_IMG (0.65)um (.*) (........) (....)
        PIPE    -close
        pnga2area -l /usr/local/ldm/logs/ldm-mcidas.log
        /usr/local/ldm/data/gempak/images/sat/\3/\5/VIS/VIS_\6_\7


In the above, ~ldm is /usr/local/ldm....but may be elsewhere on your system)

For the WMO data that you are receiving, all of the decoders that 
place the data into GEMPAK format files are included in the $GEMEXE
directory. These are the programs whicth names starting with "dc".
Typically, you can create a ~ldm/decoders directory and either
copy the dc* programs to that directory, or link the programs there.

Under $NAWIPS/ldm/etc in the gempak distribution, I have a script called
gen_pqact.csh which can be run (after sourcing the Gemenviron file).
To use, change directory to $NAWIPS/ldm/etc and run the gen_pqact.csh
script. This will produce a pqact.gempak file. The data file
locations reference by the decoders will be replaced by your environmental
variables $GEMTBL, $GEMDATA, $GEMPAK, etc. You can use the pqact.gempak
file as your pqact.conf file, or incorporate pieces from it for your site.

For many of the decoders, you should make the directory that they will write 
in ahead of time. For example, the METAR decoder which decodes surface 
observations
is dcmetr.

The pqact.conf line for dcmetr will look like:
#
# US and Canadian sfc obs and specials
#
WMO     ^S[AP].* .... ([0-3][0-9])([0-2][0-9])
        PIPE    decoders/dcmetr -v 2 -a 500 -m 72 -s sfmetar_sa.tbl
        -d data/gempak/logs/dcmetr.log
        -e GEMTBL=/home/GEMPAK5.6/gempak/tables
        data/gempak/surface/YYYYMMDD_sao.gem


This entry assumes that your dcmetr decoder is found in the ~ldm/decoders/
directory. The GEMTBL directory will  be wherever the $GEMTBL environmental
variable normally points on your system. The decoded data will be written
to the data/gempak/surface directory under your ~ldm account, so make sure 
that directory exists and is writable by the LDM. Lastly, log information
is being written to the ~ldm/data/gempak/logs directory- so again, make
sure that directory exists.

Once you have the decoder creating surface files in $GEMDATA/surface,
Garp will be able to find them when you click on the surface data
icon and select the METAR data type. Similarly for other data sets including
the satellite data.

As I have provided the GEMPAK distribution, once you define the GEMDATA
environmental variable, and set up your pqact.conf for the LDM account,
tghe GUI programs will be able to find the data as long as you follow the
directory names in the examples I have provided.

Steve Chiswell