[LDM #JKQ-274656]: NAM data question

Hi Gerry,
re: have you tried comparing sizes of individual fields for the exact same
day/time from the FTP site and in NGRID?

> Yes.  The files available from NCEP are on the order of 26MB, while those
> available via NGRID are ~15MB in size.

OK.

re: can you provide a URL for the FTP site you are referring to?

> ftp://ftpprd.ncep.noaa.gov/pub/data/nccf/com/nam/prod/nam.20120824/nam.t??z.awphys??.grb2.tm00

I just grabbed one of these files: nam.t12z.awphys12.grb2.tm00

Using 'gribinsert' (which is bundled with LDM-6.10.1, but it has to explicitly 
be
built by including --with-gribinsert (or something like this) when running
configure), I see that nam.t12z.awphys12.grb2.tm00 contains 398 GRIB2 messages.
The GRIB2 products in NGRID and CONDUIT are individual fields.  In order
to compare apples to apples, you would need to save a specific field from
NGRID and extract the same field from the file you FTP from ftpprd.ncep.noaa.gov
and compare sizes.  I will bet that the one from NGRID is actually larger
than the one from the FTP download since the one in NGRID is wrapped with
additional data before transmission in the SBN.

Cheers,

Tom
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Ticket Details
===================
Ticket ID: JKQ-274656
Department: Support Datastream
Priority: Normal
Status: Closed