<div dir="ltr"><div><div>LB,<br></div>My suggestion is to use the method of the code in zinterp and convert it to tinterp where you interpolate to isothermal surfaces. You'd probably have to create a rule to select which height in the event that a threshold is crossed multiple times, as would happen with temperature levels. Maybe take the highest one or something. It probably wouldn't take that much extra coding. Just go through <a href="http://zinterp.gs">zinterp.gs</a> and understand what each and every command does (perhaps by entering them line by line at the command prompt and evaluating the result before moving to the next step). That should provide the insight you'd need to code up a tinterp script.<br><br></div>Jeff<br></div><div class="gmail_extra"><br><div class="gmail_quote">On Mon, Feb 22, 2016 at 1:38 PM, L.B. <span dir="ltr"><<a href="mailto:bcbass2989@gmail.com" target="_blank">bcbass2989@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr">Anyone have any ideas for calculating a field which contains the -20C isotherm heights in meters?<div><br></div><div>I have thought of a few ways, but they are only giving me pressure levels. I tried using the fndlvl function:</div><div><br></div><div>define m20lev = fndlvl (tmpprs, const(tmpprs,253.15), z=1, z=80) </div><div><br></div><div>This just gives me the pressure levels of the -20C isotherm. I suppose I could use teh hypsometric equation after using the fndlvl function. <br><br>I also thought of using the <a href="http://zinterp.gs" target="_blank">zinterp.gs</a> script, but again, this wants me to input the pressure level to interpolate to heights. My pressure levels vary, so this will not work. I fell like I'm missing something really obvious, but I can't put my finger on it.<br clear="all"><div><div><div dir="ltr"><div><div dir="ltr"><div><b>-------</b></div>William (L.B.) LaForce<br>Meteorologist<div><a href="http://www.tornadoinsanity.com" target="_blank">www.tornadoinsanity.com</a></div></div></div></div></div></div>
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<br></blockquote></div><br><br clear="all"><br>-- <br><div class="gmail_signature">Jeff Duda<br>Graduate research assistant<br>University of Oklahoma School of Meteorology<br>Center for Analysis and Prediction of Storms<br></div>
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