<div dir="ltr">Hi, Steve.<div><br></div><div>I've tested the fndlvl function this way:</div><div><a href="http://prntscr.com/h6m908">http://prntscr.com/h6m908</a><br></div><div><br></div><div>and it worked very well, as you can see in the display. <b>Results in hPa</b>.</div><div><br></div><div>I got the same result for:</div><div> define H=fndlvl(tmpprs,const(tmpprs,273.16),lev=1000,lev=400)<br></div><div>d H</div><div><br></div><div>With shaded:</div><div><a href="http://prntscr.com/h6mb2j">http://prntscr.com/h6mb2j</a><br></div><div><br></div><div>As you say you want "<span style="font-size:12.8px">to determine the freezing level in meters (or feet)", my guess is tath your data is in meters (or some other similar linear vertical grid), while the fndlvl function needs the gridded data in pressure vertical levels.</span></div><div><span style="font-size:12.8px"><br></span></div><div><span style="font-size:12.8px">P.S.: If you have grid data in pressure levels, after calculating the freezing level in hPa, you can convert the result from pressure to meters (for example, using the hypsometric equation). </span></div><div><span style="font-size:12.8px"><br></span></div><div><span style="font-size:12.8px">Hope this helps.</span></div><div><span style="font-size:12.8px">Regards, </span></div><div><br></div></div><div class="gmail_extra"><br clear="all"><div><div class="gmail_signature" data-smartmail="gmail_signature"><div dir="ltr"><br style="color:rgb(0,0,0);font-family:"times new roman","new york",times,serif;font-size:16px"><span style="color:rgb(0,0,0);font-family:"times new roman","new york",times,serif;font-size:16px">-- </span><br style="color:rgb(0,0,0);font-family:"times new roman","new york",times,serif;font-size:16px"><div style="color:rgb(0,0,0);font-family:"times new roman","new york",times,serif;font-size:16px"><span name="x"></span>Prof. Ricardo Hallak<br>Laboratório de Meteorologia de Mesoescala - LMM<br>Departamento de Ciências Atmosféricas<br>Instituto de Astronomia, Geofísica e Ciências Atmosféricas<br>Universidade de São Paulo<br><br>Phone: +55(11)3091-4698</div></div></div></div>
<br><div class="gmail_quote">2017-11-04 14:37 GMT-02:00 Steve Young <span dir="ltr"><<a href="mailto:shy9@earthlink.net" target="_blank">shy9@earthlink.net</a>></span>:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div lang="EN-US" link="#0563C1" vlink="#954F72"><div class="m_2711428274072055521WordSection1"><p class="MsoNormal">I am trying to use GrADS to determine the freezing level in meters (or feet). I can use the following to determine the upper air surface where T=273.16 but am unable to figure out how to calculate/extract/determine HGT(LEV=H). This command gives an error of invalid expression. I welcome any suggestions.<u></u><u></u></p><p class="MsoNormal"><u></u> <u></u></p><p class="MsoNormal">'set gxout shaded'<u></u><u></u></p><p class="MsoNormal">'H=fndlvl(air, const(air, 273.16), Lev=1000, lev=400)'<u></u><u></u></p><p class="MsoNormal">'d H'<u></u><u></u></p><p class="MsoNormal">'run cbar'<u></u><u></u></p></div></div><br>______________________________<wbr>_________________<br>
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