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20050621: Gempak - Decoding ACARS data



Justin,

It seems that FSL has updated/changed the CDL of their file, now
at 1.7 according to your dump.

The decoder is looking for certain known identifiers, and after not finding
"rh_probe" as one of the variables, it is exiting the netcdf routine without 
decoding the data. It would appear that the CDL is now identifying the 
TAMDAR RH as sensor1RelativeHumidity and sensor2RelativeHumidity.

I'll have to update the decoder accordingly.

Steve Chiswell
Unidata User Support





>From: "Justin Sharp" <address@hidden>
>Organization: UCAR/Unidata
>Keywords: 200506212049.j5LKnpB1007873

>Institution: Bonneville Power Administration (DoE)
>Package Version: 2.1
>Operating System: Redhat Linux
>Hardware Information: HP XW 8200 Workstation
>Inquiry: The weather group at BPA has recently been granted access to ACARS da
> ta by FSL.  However, since our machines sit on a DMZ behind a proxy server, w
> e have to use the FSL Madis FTP server, rather than getting the data from FSL
> \'s ldm.
>
>I figured that these files would have the same form as those on the ldm and th
> at I could push them into dcacars to convert them from netCDF to gempak forma
> t.  However, I can\'t seem to get this to work and am now wondering if the fi
> le contents are different.
>
>Do you know if these files will be the same, and if so, have you any idea what
>  I\'m doing wrong?
>
>Here\'s what I\'m doing (from the ~ldm directory):
>decoders/dcacars -v -x -f /tmp/20050621_1600 -e GEMTBL=/usr/local/nawips/gempa
> k/tables -l - data/gempak/acars/YYYYMMDDHH_acars.gem
>
>I\'ve also tried outputing to file test.gem.
>
>Here\'s the log message (with the -v and -x flags):
>Jun 21 20:39:54 dcacars[7027]: Starting up
>        putenv GEMTBL=/usr/local/nawips/gempak/tables
>        will get input from /tmp/20050621_1600
>        decode_acars /tmp/20050621_1600 miss -9999 ier 0 cdfid 3
>        decoding ncacars
>        version name len is 3
>        version type is NC_CHAR 1.7 VAL 1.700000
>        CDF file version is 1.700000
>Jun 21 20:39:54 dcacars[7027]: MADIS ACARS data
>Jun 21 20:39:54 dcacars[7027]: No pressure variable, will calculate
>Jun 21 20:39:54 dcacars[7027]: correctedWVMR not present
>        encrypted name length is 12
>Jun 21 20:39:54 dcacars[7027]: Warning: Tail number exceeds 8 characters, will
>  truncate on storage
>Jun 21 20:39:54 dcacars[7027]: could not get variable information
>Jun 21 20:39:54 dcacars[7027]: could not decode data 0
>Jun 21 20:39:54 dcacars[7027]: Exiting
>
>I\'ve attatched the oldest acars file I could download from fsl (so that nobod
> y gets upset) to see if you can verify if it is compatible with dcacars.  Its
>  a valid netCDF file (viewed it with ncdump).  Of course, I\'m gunzipping it 
> before trying to run dcacars.
>
>Help is much appreciated, as I\'m pulling out what little hair I have left :)
>
>Thanks,
>
>Justin
>
>
>
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