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19990611: decoding U/A files manually

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  • Subject: 19990611: decoding U/A files manually
  • Date: Fri, 11 Jun 1999 13:41:24 -0600
>From: Robert Mullenax <address@hidden>
>Organization: .
>Keywords: 199906111831.MAA26814

>I received some raw upper air files (*.wmo) and
>want to decode them using dcuair to make *.gem files.
>I tried cat 99060112_upa.wmo | dcuair PACK 990601_upa.gem
>but get no headers processed with DC -11 error.  Whta
>am I doing wrong?
>
>Thanks
>Robert Mullenax
>

Robert,

When decoding archived data, you need to use the "-c" flag to set the
"current" time for dcuaur rather than using the system clock for current time.

The dc decoders use the "current" time to ascertain if the data they are seeing
is valid- for example, if a station mistakenly sends yesterday's observation
then the decoder will detect this, and if it is greater than "-b hours" old
the data will be discarded. The "-b" flag tells the decoder how far before
the "current" time to allow reports.

For decoding Jun 1 data that is stored in hourly files, try:
cat 990601*_upa.wmo | dcuair -c 990602/0000 -b 30 PACK YYMMDD_upa.gem

The dc decoders rely on the time in the data in metar and upperair for
determining the YYMMDDHH templates rather than just assuming the WMO day/hour 
on the input is correct. Otherwise, you's see spurious files often a month
old being created when old data or bad data get on the GTS.

Steve Chiswell