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20010620: GDATTIM=first

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  • Subject: 20010620: GDATTIM=first
  • Date: Wed, 20 Jun 2001 19:47:33 -0600
>From: Clint Rowe <address@hidden>
>Organization: UCAR/Unidata
>Keywords: 200106202253.f5KMrp118853

>Chiz,
>
>I don't know if this is a well-known "feature" in gempak, but when I specify 
>GDATTIM=first. I get the first time in the last day of data in the file
>when the file has data from more than one date in it.  I just noticed this
>today, and it wasn't what I expected.  I expected "first" to mean the first
>(i.e., earliest) date/time in the file.
>
>Clint
>
>====================================================================
>Clinton M. Rowe
>Associate Professor 
>Meteorology/Climatology Program                  phone:(402)472-1946
>Department of Geosciences                          fax:(402)472-4917
>University of Nebraska-Lincoln                        address@hidden
>
>

Clint, 
Yes, FIRST and LAST in GDATTIM refer to the latest run time in the file.
Typically, if you wanted to generate a loop for all the forecast times
for a specific run, you could use GDATTIM=FIRST-LAST in specific programs.

You will also find other GDATTIM abbreviations like ALLF000 for example
which will give you all the F000 times in the file.

When using file templates now, such as GDFILE=eta, the GDATTIM abbreviations 
will
refer to the forecast times for the most recent file.

The alternative to what you indicate above would be for "analysis" grids, such 
as if
you run oabsfc on a series of observations. In this case, the GDATTIM is just 
YYMMDD/HHMM
(eg no Fhhh time). 

Steve Chiswell