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20010928: Decoding AVN data available from the NCEP FTP site



>From: Owen Cooper <address@hidden>
>Organization: NOAA Aeronomy Laboratory
>Keywords: 200109281630.f8SGUC126986 NCDP AVN FTP IDD nic McIDAS

Owen,

>[Sorry if this message has already been sent, but we've had problems today
>with our e-mail software]

This is the only copy we got.

>I have two questions for you:
>
>1) How do I find out the resolution of the AVN data broadcast from
>NOAAport?

One quick way is to do an expanded listing of the grids after they have
been decoded into McIDA GRID files:

GRDLIST RTGRIDS/AVN FORM=ALL

>I need the 1 x 1 degree northern hemisphere data set, at 50 mb
>intervals.  I know that these data are available from the NCEP ftp site,
>but it would be nice if we could get them through the LDM.

The data from the NCEP FTP site are what is in the CONDUIT IDD feed.
I wish I could simply advise you to signup for this feed, but it has been
very unreliable due to a network bottleneck back at/near the source.

>We run the LDM
>here at the NOAA Aeronomy Lab like a black box, and we need to learn more
>about it.  The AVN data that we are decoding are not available every 50
>mb.

Right.  The ones in NOAAPORT are more coarse than the ones available from
the NCEP FTP site.

>So we are wondering if the data are really coming in, but maybe we're
>not decoding all of the levels.

You are most likely decoding everything that comes in the IDD.  One would
have to go out of his/her way to not decode all levels in McIDAS-XCD.

>I've spent 40 minutes hunting around on
>the MCIDAS and NOAAport web pages but can't find the info. I need. So if
>you can point me in the right direction, I would really appreciate it.

If the right info you are looking for is how to get the data on the IDD,
you would need to request the CONDUIT feed.  The volume in this feed
is HUGE, so one has to be careful at the onset to make sure that disk
storage and network resources do not get exhausted.  Again, I hate to
say that the CONDUIT feed is not very reliable - we want it to be reliable,
but there are factors at work here that are beyond our control.  I can
initiate the connection if you decide that you want to try it anyway.

>2) My second question is contingent upon the first.  If I do have to
>resort to ftp'ing the AVN data from the NCEP site, where do I go to learn
>how to feed the GRIB data into the MCIDAS decoders?

The second piece of bad news for you today is that the McIDAS decoders do
not yet handle the 1x1 AVN data.  I believe that someone at SSEC is looking
into grid decoding, but I am not 100% sure.  Since you are not the first user
that as asked about this data, it may be time for me to dig into the code
and get things working for the higher resolution data from the NCEP FTP
site.

>Thank you for any info. you can send my way,

I will see what is going on at SSEC in this regard and see if I need to
launch off on a development wag.

Tom


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