Re: plotting NARR data

From: Clint Rowe <crowe_at_nyahnyahspammersnyahnyah>
Date: Wed, 06 Aug 2008 14:03:21 -0500

Dave and Mary,

Thanks for your replies. I was, in fact, referring to the slivers
along the sides of the map. I found the reference powerpoint your
mentioned, Dave, a little while ago and determined that was the issue.

Thanks again for your help.
Clint

On Wed, 2008-08-06 at 12:56 -0600, Dave Allured wrote:
> Clint,
>
> Are you referring to the small slivers of missing data in three
> corners as seen on this page?
>
> http://www.ncl.ucar.edu/Applications/narr.shtml
>
> The original NARR Eta-12 model grid is regridded to NCEP standard
> grid 221 for public distribution, Lambert conformal conic, which you
> see here.
>
> There is a slight mismatch between the chosen grid boundaries,
> resulting in the slivers of missing data. This is discussed on
> pages 39, 41, 42 of this early Powerpoint summary from NCEP (2005).
> Page 42 is the picture that speaks a thousand words:
>
> http://www.emc.ncep.noaa.gov/mmb/rreanl/narr.ppt
>
> Dave Allured
> CU/CIRES Climate Diagnostics Center (CDC)
> http://cires.colorado.edu/science/centers/cdc/
> NOAA/ESRL/PSD, Climate Analysis Branch (CAB)
> http://www.cdc.noaa.gov/
>
> Clint Rowe wrote:
> > I'm trying to plot NARR data (GRIB format) and am able to reproduce the
> > examples shown on the NCL website. I have a question about the maps
> > that are produced, however. If the data are on a native grid and the
> > map is specified by the data in the GRIB file (corners, true parallels,
> > central meridian, etc) then why does the data not fill the entire
> > rectangular box plotted by NCL? Specifically, why are edges of the data
> > area curved?
> >
> > Clint
>
> _______________________________________________
> ncl-talk mailing list
> ncl-talk_at_ucar.edu
> http://mailman.ucar.edu/mailman/listinfo/ncl-talk

On Wed, 2008-08-06 at 12:18 -0600, Mary Haley wrote:
> Hi Clint,
>
> In order to plot data on a native grid, you have to do two things:
>
> 1) Get the map projection exactly right.
> 2) Set res_at_tfDoNDCOverlay = True
>
> Of course, you must also be certain that your data is actually on the
> native grid that you believe it is on. Are you doing #2, and still
> seeing the same results?
>
> If so, perhaps you can try something else. If you have the
> corresponding
> 2D lat/lon values associated with your data, then attach them to your
> data as "lat2d" and "lon2d":
>
> data_at_lat2d = LAT
> data_at_lon2d = LON
>
> "LAT" and "LON" need to be replaced with whatever these 2D arrays are
> called
> in your script, and "data" should be the name of the data variable
> you are plotting.
>
> Then, make sure res_at_tfDoNDCOverlay is either not set at all, or is
> set to False.
>
> --Mary
>

-- 
====================================================================
Clinton M. Rowe
Associate Professor
Meteorology/Climatology Program                  phone:(402)472-1946
Department of Geosciences                          fax:(402)472-4917
University of Nebraska-Lincoln                        crowe1_at_unl.edu
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Received on Wed Aug 06 2008 - 13:03:21 MDT

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