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19990216: satellite data with gempak and mcidas

>From: address@hidden (Kathy Fryberger)
>Organization: sdsmt
>Keywords: 199902161852.LAA09399

>*****************************************************************
>Kathy,
>
>GOES-9 no longer transmits data. In the Unidata/Wisconsin data stream
>you will receive GOES-8 and GOES-10.
>
>If you are decoding the area files from the LDM with the lwtoa3
>action with names like AREA0120 etc., then you can use the
>gempak areaInfo program, and the nsat_links script to maintain
>links to the files in a gempak tree so that Garp and nsat
>can view the names with more useful names.
>
>Verify that you have areaInfo in the $GEMEXE directory and
>that it can properly identify the area files in your McIDAS
>directory:
>
>eg, a GOES 10 VIS image should be found in AREA0120:
>% areaInfo /var/data/mcidasd/AREA0120
>/var/data/mcidasd/AREA0120
>VIS_990216_0000 GOES-10 4km
>
>If areaInfo does not correctly identify this as GOES-10, an instead says "unk"
> ,
>then you would need to update your areaInfo program with the patch I put out 
>last summer when GOES-10 came on line.
>
>Since you say you are not getting GOES-8 links either, then you probably need 
> to
>investigate the nsat_links script to see what is being generated.
>The $NAWIPS/bin/scripts/nsat_links script has some variables at the
>beginning of the script. First, make sure that the script has the 
>appropriate path to source the Gemenviron file. Next, make sure the
>areadir variable is set to the appropriate directory with your
>mcidas AREA files. Lastly, verify that the NSAT directory points
>to your $SAT directory (the directory that nsat and garp look in
>for their images).
>
>If all of the above are ok, then make sure the account that is running the
>nsat_links script has the appropriate permissions to read the area
>files from the mcidas directory and can create the symbolic links in the
>gempak area. Check the links in the gempak area and make sure they
>exist. If they don't exist since January, then make sure the cron which
>is running the nsat_links script can still execute the script. 
>Try running the script by hand to see if it prints out any messages
>which may help diagnose where things are getting fouled up.
>
>Steve Chiswell
>Steve--I checked all these things and everything seems fine except this one
>thing you mentioned:
>"...make sure the cron which is running nsat_links script can still....."
>Oops-----what cron?   How is it executed?  Who should be running it and
>how often?  I think this is my problem.....since the nsat_links script
>runs just fine all by itself.  And I don't remember ever setting up a cron
>for it.   thanks!
>**********************************************************
>address@hidden  kathy fryberger  605-394-2291
>South Dakota School of Mines & Technology
>Rapid City, South Dakota 
>**********************************************************
>

Kathy,

The McIDAS files use the circular naming, like AREA0120-AREA0129 for
the last 10 GOES-10 VIS images. In order to maintain current links from
those file names to the GEMPAK style names like GOES-10/4km/VIS/VIS_990217_1215
the nsat_links script needs to be run at least once per hour, to remove old 
links, and generate new links. Since the McIDAS names are circular and
repeat every 10 hours, the script purges out the old links (eg the KEEP
variable tells the script how many links to keep).

Since GOES-8 and GOES-10 files come in throughout the hour, I run the 
script several times during the hour with a crontab entry such as:
5,15,25,35,45 * * * * /bin/csh /home/gempak/NAWIPS-5.4/bin/scripts/nsat_links 
1>>/dev/null 2>&1

I run the script as the gempak user, but can be run by any user that has the 
permission
to write the symbolic links in the $SAT tree- just make sure the "source 
Gemenviron"
line in the script has the appropriate path so that whatever user is running
the script gets the appropriate gempak environment set.

The script is installed in $NAWIPS/bin/scripts (eg it is copied to that
directory when gempak is built from the $NAWIPS/unidata/scripts directory),
so make sure you preserve your copy after you edit paths if you ever reinstall
gempak.

Steve Chiswell