On Wed, Apr 20, 2011 at 10:39 AM, Meredith Croke <span dir="ltr"><<a href="mailto:mcroke@airdat.com">mcroke@airdat.com</a>></span> wrote:<br><div class="gmail_quote"><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">
<div lang="EN-US" link="blue" vlink="purple"><div><p class="MsoNormal">Hi Everyone,</p><p class="MsoNormal">I’m looking to plot a contour plot of LFC height, similar to the graphic on the SPC Mesoscale Analysis page, my control file does not output LFC directly, is there anyway I can calculate this in grads?</p>
<p class="MsoNormal"> </p></div></div></blockquote><div><br></div><div>The opengrads bundle includes a GS-udf function to compute the pressure & temperature at the lifiting condensation level (plcl, tlcl):</div><div><br>
</div><div> <a href="http://opengrads.org/doc/udxt/saakeskus/">http://opengrads.org/doc/udxt/saakeskus/</a></div></div><div><br></div><div>(For implementation, see file plcl.gsf/tlcl.gsf under Contents/Resources/Scripts.)</div>
<div><br></div><div>From the LCL, <span class="Apple-style-span" style="font-family: sans-serif; font-size: 13px; line-height: 19px; ">follow the <a href="http://en.wikipedia.org/wiki/Moist_adiabatic_lapse_rate" class="mw-redirect" title="Moist adiabatic lapse rate" style="text-decoration: none; color: rgb(6, 69, 173); background-image: none; background-attachment: initial; background-origin: initial; background-clip: initial; background-color: initial; background-position: initial initial; background-repeat: initial initial; ">moist adiabatic lapse rate</a> until the temperature of the parcel reaches the air mass temperature, at the <a href="http://en.wikipedia.org/wiki/Equilibrium_level" style="text-decoration: none; color: rgb(6, 69, 173); background-image: none; background-attachment: initial; background-origin: initial; background-clip: initial; background-color: initial; background-position: initial initial; background-repeat: initial initial; ">equilibrium level</a> (EL). If the temperature of the parcel along the moist adiabat is warmer than the environment on further lift, one has found the LFC. The wikipedia has some useful information:</span></div>
<div><br></div> <a href="http://en.wikipedia.org/wiki/Level_of_free_convection">http://en.wikipedia.org/wiki/Level_of_free_convection</a><div><br clear="all">If someone comes up with such GS udf for computing the LFC I'd be more than glad to include it in the next opengrads release. Any volunteer?</div>
<div><br></div><div> Good Luck,</div><div><br></div><div> Arlindo</div><div><br></div><div>-- <br>Arlindo da Silva<br><a href="mailto:dasilva@alum.mit.edu">dasilva@alum.mit.edu</a><br>
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