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<div class=Section1>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>I’m confused about zinterp and pinterp. What I want to do
is return a height given variable pressure levels.<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>So I have LCL pressures for all the grid points, but I want to
translate that into a height AGL. My understanding is that you need to have one
static layer (IE all 850mb) to return heights from a pressure level given
zinterp.<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>Is that correct…is there another way to do it?<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>I came up with this function but I’m getting errors. I’m
sure I don’t have to reinvent the wheel:<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>function getheight(Pressure)<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>*FIND THE NEAREST PRESSURE LEVEL ABOVE<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>'define apres = Pressure'<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>while (math_fmod(apres,25) != 0)<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'> 'apres = apres - 1'<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>endwhile<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>*FIND THE NEAREST PRESSURE LEVEL BELOW<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>'bpres = apres + 25'<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>'Set LEV bpres'<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>"define l2="HGTprs<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>'Set LEV apres'<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>"define l1="HGTprs<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>'Percent = (Pressure - apres) / 25'<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>'Distance = l1 - l2'<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>if (Distance < 0) ; 'Distance = 0' ; endif<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>"define height ="nint(l1 - (Distance * Percent))<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>return (height)<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<div style='border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0in 0in 0in'>
<p class=MsoNormal><b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'>From:</span></b><span
style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'>
gradsusr-bounces@gradsusr.org [mailto:gradsusr-bounces@gradsusr.org] <b>On
Behalf Of </b>Arlindo da Silva<br>
<b>Sent:</b> Monday, April 25, 2011 8:14 PM<br>
<b>To:</b> GrADS Users Forum<br>
<b>Subject:</b> Re: [gradsusr] zinterp.gs<o:p></o:p></span></p>
</div>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>On Fri, Apr 22, 2011 at 1:43 PM, Jeffrey Duda <<a
href="mailto:jdduda@iastate.edu">jdduda@iastate.edu</a>> wrote:<o:p></o:p></p>
<div>
<blockquote style='border:none;border-left:solid #CCCCCC 1.0pt;padding:0in 0in 0in 6.0pt;
margin-left:4.8pt;margin-right:0in'>
<p class=MsoNormal style='margin-bottom:12.0pt'>Meredith,<br>
I know the way Grads scripting works can be confusing with the quoting of
commands and calling of functions. That's all you're doing wrong.
I've attached an edited version of your <a href="http://zinterp.gs"
target="_blank">zinterp.gs</a> file to show you how to do it. Notice that
I only changed the top few lines. To work this, you need to run the <a
href="http://zinterp.gs" target="_blank">zinterp.gs</a> script. Your <a
href="http://test3.gs" target="_blank">test3.gs</a> script would work but you
need to remove the call from any quotes and you need the actual code that makes
up the function to be located within the script file. Unfortunately Grads
doesn't know that your function is sitting in some other .gs file, even if it
is in the same directory.<o:p></o:p></p>
</blockquote>
<div>
<p class=MsoNormal><o:p> </o:p></p>
</div>
<div>
<p class=MsoNormal>If you are using an opengrads build, another possibility is
to implement <a href="http://zinterp.gs">zinterp.gs</a> as a GS udf as
explained here:<o:p></o:p></p>
</div>
<div>
<p class=MsoNormal><o:p> </o:p></p>
</div>
<div>
<p class=MsoNormal> <a
href="http://opengrads.org/doc/udxt/gsudf/">http://opengrads.org/doc/udxt/gsudf/</a><o:p></o:p></p>
</div>
<div>
<p class=MsoNormal><o:p> </o:p></p>
</div>
<div>
<p class=MsoNormal>Better yet, the opengrads bundle comes with zinterp()
implemented as an extension:<o:p></o:p></p>
</div>
<div>
<p class=MsoNormal><o:p> </o:p></p>
</div>
<div>
<p class=MsoNormal> <a
href="http://opengrads.org/doc/udxt/libbjt/libbjt.html#zinterp_field_zgrid_zlev__l_s_p__">zinterp(FIELD,ZGRID,ZLEV,[-l|-s|-p])</a><o:p></o:p></p>
</div>
<div>
<p class=MsoNormal><o:p> </o:p></p>
</div>
<div>
<p class=MsoNormal> so just use it.<o:p></o:p></p>
</div>
<div>
<p class=MsoNormal><o:p> </o:p></p>
</div>
<div>
<p class=MsoNormal> Arlindo<o:p></o:p></p>
</div>
<div>
<p class=MsoNormal><o:p> </o:p></p>
</div>
<div>
<p class=MsoNormal><o:p> </o:p></p>
</div>
<div>
<p class=MsoNormal><o:p> </o:p></p>
</div>
<div>
<p class=MsoNormal><o:p> </o:p></p>
</div>
</div>
<p class=MsoNormal><br clear=all>
<br>
-- <br>
Arlindo da Silva<br>
<a href="mailto:dasilva@alum.mit.edu">dasilva@alum.mit.edu</a><o:p></o:p></p>
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