Djordje,<br>Since cdiff performs a centered difference, if you use the expressions suggested by another Grads user on this thread, you would only want to use dx since 2*dx is already implied in the definition.<br><br>Jeff<br>
<br><div class="gmail_quote">On Thu, Aug 9, 2012 at 1:50 AM, Djordje Romanic <span dir="ltr"><<a href="mailto:djordje8@gmail.com" target="_blank">djordje8@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
Thanks, <br clear="all"><br>Since I only need the pressure gradient, and not the pressure gradient force, I should exclude 1/rho. Just one clarification. When I use cdiff function for pressure (e.g. in LON direction), should I divide it with dx or 2*dx. I believe that 2*dx would be correct. <br>
<br>Regards,<br>Djordje<br>
<br><br><div class="gmail_quote">On Wed, Aug 8, 2012 at 7:08 PM, Jeff Duda <span dir="ltr"><<a href="mailto:jeffduda319@gmail.com" target="_blank">jeffduda319@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
The pressure gradient is simply 1/rho * del(p), where del(p) is the gradient operator, which can be displayed in Grads using the mathematical decomposition of the gradient operator (i.e., derivatives in the x- and y-directions). Use cdiff for those derivatives. Note, you'll have to define your x- and y- grid spacing values as well. See the examples on the <a href="http://www.iges.org/grads/gadoc/gradfunccdiff.html" target="_blank">cdiff help page</a> for how to do that.<br>
<br>Jeff Duda<br><br><div class="gmail_quote"><div><div>On Wed, Aug 8, 2012 at 5:48 AM, Djordje Romanic <span dir="ltr"><<a href="mailto:djordje8@gmail.com" target="_blank">djordje8@gmail.com</a>></span> wrote:<br>
</div></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div><div>
Dear Users, <br><br>I have to calculate the pressure gradient in a given
area (Southeast Europe) and I have a pressure date at 2.5 x 2.5 degrees
(reanalysis data). Does anyone know how to calculate it in GrADS and
how to show the results in the vector form? <br>
<br>Thanks in advance.<br><br>Regards,<br clear="all">Djordje Romanic<br>M.Sc. in Meteorology<br>Cell: <a href="tel:%2B38164%20254%203539" value="+381642543539" target="_blank">+38164 254 3539</a><br><a href="http://www.linkedin.com" target="_blank">www.linkedin.com</a> (Djordje Romanic profile)<br>
<br>
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<br></blockquote></div><span><font color="#888888"><br><br clear="all"><span class="HOEnZb"><font color="#888888"><br>-- <br>Jeff Duda<br>Graduate research assistant<br>University of Oklahoma School of Meteorology<br>Center for Analysis and Prediction of Storms<br>
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<br></blockquote></div><br><br clear="all"><br>-- <br>Jeff Duda<br>Graduate research assistant<br>University of Oklahoma School of Meteorology<br>Center for Analysis and Prediction of Storms<br><br>