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20040812: Composite Radar Problems? (cont.)

>From: Tom McDermott <address@hidden>
>Organization: SUNY Brockport
>Keywords: 200408122329.i7CNTOaW008533 IDD FNEXRAD

Tom,

re: Which composite radar product(s) are you having problems with?

>The problems are with all the  PNG compressed FNEXRAD image (AREA) files,
>which I decode as:
>
>FNEXRAD        ^pnga2area Q5 (..) (...) RADAR (....) (.*) (........) (....)
>       PIPE    -close
>       pnga2area -vl logs/ldm-mcidas.log
>       -a etc/SATANNOT -b etc/SATBAND
>       data/gempak/nexrad/RADAR/\4/\3/\3_\5_\6
>
>The error message I'm getting with GARP is:
>
>GEMPAK: [IM 1]  No image type entry for file
>/weather/ldm/data/gempak/nexrad/RADAR/6km/BREF/BREF_20040812_2341
>
>After I sent the 1st message, I recalled that there was a problem with
>composite generation on the atm nsf server several weeks ago, and because
>yesterday (and today) the ldm server there seemed to be having problems
>(would not respond to ldmpings, but responded to pings), I switched my
>FNEXRAD feed from atm.geo.nsf.gov to unidata2.ssec.wisc.edu about the same
>time you did the NOTIFYME on my server, but I still cant see the
>images, so I guess that that's not it.

The PNG compressed FNEXRAD radar images are created by a McIDAS GRIB to
AREA conversion routine (GRIB2IMG).  This routine uses GRIB tables to
add a calibration to the resultant AREA file.  The GRIB tables that
were being used were lost at the same time the problems surfaced on the
machine generating the products (motherlode.ucar.edu, not
atm.geo.nsf.gov; atm simply relays the products).  Yesterday, I worked
on a code update to the GRIB to AREA conversion routine that is more
general in its ability to get GRIB parameter information for the
calibration of the resultant images, and that update seems to work with
no problems.

Evidently, some modification to the base code being used by the GRIB to
AREA conversion routine is now having an unintended and, quite frankly,
bewildering effect on two distinctly different things:

- the navigation for the 1 km floater composite which is now flipped
  east to west

- the AREA file header value that GARP tables are using to know
  what the images are so they can be correctly colorized, etc.

I was unaware of the second item until this email from you.  I had a
suspicion of the first item, but I was unable to attend to it today.

I will be working on the first problem now; I will need to talk with
Steve Chiswell to see what AREA file header parameter changed so that
GARP configuration tables are no longer working.

Tom
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