Cross section using maskout for terrain

[Charles Seman]

Dan,

Found a file containing a script "orog.gs" posted to the Listserv by
Wesley Ebisuzaki (attached).

I hope this helps,
Chuck

Dan Leins wrote:
> Bill,
>
> Thanks for the suggestion. I attempted to set up a mask using the
> difference between hgtprs and hgtsfc. Unfortunately this produced
> similar "boxy" results like the images I attached initially.
>
> What routine does maskout use to "mask out" the negative areas? Is
> there a way for it to use the same smooth routine used when contouring?
>
> Dan
>
> On Wed, Jul 2, 2008 at 11:18 AM, Bill Bua <Bill.Bua at noaa.gov
> <mailto:Bill.Bua at noaa.gov>> wrote:
>
>     Dan --
>
>     I suspect it's because you're using lev, which is discretized into
>     layers, and shading, resulting in 'boxy' plots to the nearest
>     level set
>     up in your control file and "masking out" anything that has a value of
>     your variable t1pm1-lev < 0.  The plot of t1pm1-lev is smooth
>     because of
>     the plotting routine used for contours.
>
>     I'm not sure if this will work better, but perhaps you can use the
>     model
>     topographic height if it's available and subtract the height of the
>     'lev' pressure surfaces as an alternative.  Your mask might look more
>     like the topography than the levels if you do so.
>
>     Hope this helps.
>
>     Bill Bua
>
>     Dan Leins wrote:
>
>         All,
>
>         I am attempting to draw a simple cross section showing temperature
>         across a model domain and I would like to maskout the area below
>         ground. I have seen some traffic on this issue. I see that I
>         should be
>         able to define the terrain by subtracting pressfc/100 from
>         lev, with
>         all negative values being areas that are underground. Then using
>         maskout, I can do the following:
>
>         d maskout(tmpprs,t1pm1-lev)
>
>         This gives me something in the ballpark of what I'm looking for
>         (image1.png), but the shaded area looks very gridded in
>         nature. When I
>         simply plot a contoured plot of 't1pm1-lev', it doesn't look
>         gridded
>         at all and appears nice and smooth (image2.png). The model grid
>         spacing is 4km and I'm covering about 500km in my cross
>         section so I'm
>         guessing things should appear relatively smooth.
>
>         Why does maskout produce results that look so gridded?   Is
>         there any
>         other way I can maskout the underground areas but still have a
>         nice
>         crisp outline of the terrain?
>
>         Thanks!
>         Dan Leins
>
>
>         ------------------------------------------------------------------------
>
>
>         ------------------------------------------------------------------------
>
>

--

Please note that Charles.Seman at noaa.gov should be considered my NOAA
email address, not cjs at gfdl.noaa.gov.

********************************************************************
 Charles Seman                                Charles.Seman at noaa.gov
 U.S. Department of Commerce / NOAA / OAR
 Geophysical Fluid Dynamics Laboratory         voice: (609) 452-6547
 201 Forrestal Road                              fax: (609) 987-5063
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