<html><head></head><body bgcolor="#FFFFFF"><div><br></div><div><br>On Nov 10, 2011, at 12:13 PM, Jeff Duda <<a href="mailto:jeffduda319@gmail.com">jeffduda319@gmail.com</a>> wrote:<br><br></div><div></div><blockquote type="cite">
<div>Mason,<br>There is a good example of how to code temperature advection in the page for the cdiff command: <a href="http://www.iges.org/grads/gadoc/gradfunccdiff.html">http://www.iges.org/grads/gadoc/gradfunccdiff.html</a><br>
The reason for all of the crazy manipulations is because the data points on your grid are not uniformly spaced on the globe. Thus corrections have to be made to get the correct distance between individual grid points.<br>
<br></div></blockquote><div><br></div><div>If you have opengrads, the BJT extensions include very accurate advection functions, see</div><div><br></div><a href="http://opengrads.org/doc/udxt/libbjt/">http://opengrads.org/doc/udxt/libbjt/</a><div>
<br></div><div>These functions use Bott's 4-level scheme for evaluating advection.</div><div><br></div><div> Arlindo<br><div><br></div><br><blockquote type="cite"><div>Jeff<br><br><div class="gmail_quote">On Thu, Nov 10, 2011 at 11:00 AM, Wesley Ebisuzaki <span dir="ltr"><<a href="mailto:Wesley.Ebisuzaki@noaa.gov">Wesley.Ebisuzaki@noaa.gov</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">
Mason,<br>
<br>
I think that you've discovered the "private" commands used by nomads<br>
plot software for defining new variables<br>
and custom plots. The nomads plot package is a wrapper for GrADS. It<br>
has the ability to run grads .gs files that<br>
are embedded within the ctl files.<br>
<br>
<br>
<a href="http://www.cpc.ncep.noaa.gov/products/wesley/ncep_data/plot_doc.htmlhttp://www.cpc.ncep.noaa.gov/products/wesley/ncep_data/plot_doc.html" target="_blank">http://www.cpc.ncep.noaa.gov/products/wesley/ncep_data/plot_doc.htmlhttp://www.cpc.ncep.noaa.gov/products/wesley/ncep_data/plot_doc.html</a><br>
<br>
Ask NCDC for a copy of the .gs files.<br>
<div class="im"><br>
> Has anyone done this before with grads?<br>
</div>How do you expect the developers to debug the scripts?<br>
<font color="#888888"><br>
Wesley<br>
</font><div><div></div><div class="h5"><br>
<br>
<br>
Rowell, Mason D. wrote:<br>
> All,<br>
><br>
> I noticed ample comments toward the end of the ctl files available on the nomads servers from the NARR page, with a description of how to implement these in grads scripting. I tried to take this to plot temperature advection but it didn't work, b/c the last line of the comments calls for some function never provided. Has anyone done this before with grads?<br>
><br>
> Mason<br>
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</div></div></blockquote></div><br><br clear="all"><br>-- <br>Jeff Duda<br>Grad student - PhD, Meteorology<br>University of Oklahoma School of Meteorology - Center for Analysis and Prediction of Storms<br><br>
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