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19990205: oabsnd

This archive contains answers to questions sent to Unidata support through mid-2025. Note that the archive is no longer being updated. We provide the archive for reference; many of the answers presented here remain technically correct, even if somewhat outdated. For the most up-to-date information on the use of NSF Unidata software and data services, please consult the Software Documentation first.

  • Subject: 19990205: oabsnd
  • Date: Fri, 5 Feb 1999 09:44:43 -0700
John,

Mandatory levels below surface report height, but shouldn't have
temperature, dewpoint, and winds.

When gridding the data, the height values exist at those levels and
will be taken in to account. TMPC, DWPC, SPED, DRCT should be -9999.
so are not used.

When displaying levels, even from models like the RUC which
have gridpoint values below ground, it is possible to
construct a 1/0 mask (or 1/-9999) to multiply the data values by
so that the below ground levels are effectively removed from
the display. I showed how to do this several times in the
GEMPAK email archives (search on "mask" in the support archive)-
http://www.unidata.ucar.edu/glimpse/gempak/1427

In the case in the URL above, I was using the surface hght grid
from the eta, but you can grid level=sfc, parm=hght in aobsnd
to create a surface hght grid as well.

Steve Chiswell
Unidata User Support

On Fri, 5 Feb 1999 address@hidden wrote:

> Steve,
> 
> How does oabsnd handle levels that are below the lowest observed
> level (e.g., 1000 mb at DEN)?
> 
> Thanks,
> John C.
>