19990311: Y2K

>From: Mike Trexler <address@hidden>
>Organization: .
>Keywords: 199903112129.OAA25959

>This question regards the IDD feed, and LDM and how they are
>set up for Y2K compliance.  Will there be new distributions that
>need to be installed or what?  And I suppose this question also
>branches over to Gempak as well, since the realtime decoders
>might choke for a 00 year.  Can you give me an update on what
>is anticipated?
>
>Thanks
>Mike Trexler
>
>
>
>--
>__________________________________________________
>**************************************************
>******          C. Michael Trexler          ******
>******      N C State Univ. - Box 8208      ******
>******  Dept. of Mar/Earth/Atmos. Sciences  ******
>******        Research III   Rm. 100        ******
>******        Raleigh, NC 27695-8208        ******
>******        (919) 515-1447  Phone         ******
>******         (919) 515-1683  Fax          ******
>**************************************************
>--------------------------------------------------
>******        address@hidden       ******
>__________________________________________________
>
>
>

Mike,
The LDM uses unix system time (seconds since 1970), so you won't run
into any problems until at least 2038 with a 32 bit number representing
the number of seconds. 

In terms of WMO headers, they aren't even month" compliant, eg
WWUS35 KRDU 111200 means 1200Z on the 11th. no month or year
implied, so nothing there would be effected by "00".

Gempak represents dattim as YYMMDD/HHMM. The CC portion not shown
is assumed to be 19 when YY > 20, and CC=20 for YY<21.

GRIB data contains the century within the bulletin. Note that
yesr 2000 is still the 20th century (100th year). 2001 is the
first year of the 21st century. Grib gives YEAR and Century
fields (currently year=99, century=20), in year 2000,
century =20, year = 100, and in 2001, century=21 year = 1.
Therefore grib date YYYY = (century - 1)*100 + year.
The above expression will not fail according to the grib documentation.

The most likely area to expect problems would be local scripts
which archive data, create gifs, scour data, etc.

Steve Chiswell