Cross section using maskout for terrain

[Dan Leins]

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> 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
>>
>>
>> ------------------------------------------------------------------------
>>
>>
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>>
>>
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