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20020218: ldm user e-mail list and CONDUIT grid decoding



>From: Owen Cooper <address@hidden>
>Organization: NOAA Aeronomy Laboratory
>Keywords: 200202181908.g1IJ8Dx01947 LDM email

Owen,

re: what is the problem with the Unidata-Wisconsin (LDM feed type MCIDAS)
datastream?

>Thanks for the ldm e-mail info. There's no problem right now with the
>datastream,

Phew!  I've got enough on my plate just now...

>as far as I know, but I will be producing several MCIDAS
>products for a field study in April and May and I'll need to know of any
>problems with the real-time datastream.

Please remember that you can _always_ get access to these images through
a number of different ADDE servers.  So, if the LDM ingest of the images
was down at your site for some reason but still up at others, you could
get the data you need with a simple ADDE IMGCOPY.

re: mods to gribdec that allow decoding of non-ensemble CONDUIT grids
including the 1x1 degree AVN

>Tom, this is fantastic news!  I was just thinking today how nice it would
>be for me to overlay the 1x1 AVN on some water vapor images. Just let me
>know when the tarfile is ready.

Will do.

Again, in order to completely work with McIDAS, you will have to load
the latest addendum (the thing that is not yet available) and rebuild
your distribution.  The main reason for this is that the size of grids
allowed by the current release is too small for some of the grids that
you may want to decode.  In particular, we (Steve Chiswell using
GEMPAK) are producting base reflectivity composites that get sent in
the IDD FNEXRAD feed as grib messages.  Those gribs contain grids that
are greater than the maximum size currently allowed by McIDAS, so a
couple of include files (grib.h and gridparm.inc) need to be updated
(as does makefile) and then a make all done.  Along with those mods, I
have several for XCD that will allow it to decode the NEXRAD composite
grib messages.

Today, I am working on a grib to image converter specifically for the
radar composites.  When finished, I will be using it to populate ADDE
datasets that everyone will be allowed access to.  Stay tuned...

>So how will this work?  Do I run the ldm in an off-line mode and feed the
>archived AVN 1x1 files into the ldm and then just let it do the decoding?

The standalone gribdec package can be used to read from disk files of
grib messages and write McIDAS GRID files.  

The invocation syntax looks like:

gribdec.k input_grib_file_pathame NNNN NUM=n

where:

input_grib_file_pathame - fully qualified pathname of file containing grib
                          message(s) to be converted to McIDAS GRID

NNNN                    - McIDAS GRID file number (0001 - 9999)

n                       - number of grib messages to be decoded

Now, if your site is also getting CONDUIT data, those grib messages
could be piped to the XCD process in ~ldm/etc/pqact.conf and XCD will
decode them like all of the other grib messages.

>Well, no need to give a detailed response here if this info. will be
>included in the tarfile.

Do you get the CONDUIT data?  I don't think so, but you may want to check
with Hsie.

>Thanks!

No worries.  Talk to you later...

Tom


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