Yaqiang,<br>You are exactly correct.<br><br>Jeff Duda<br><br><div class="gmail_quote">On Sun, Nov 14, 2010 at 9:22 PM, Yaqiang Wang <span dir="ltr"><<a href="mailto:yaqiang.wang@gmail.com">yaqiang.wang@gmail.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;">The GrADS documentation said that the cdiff function may be used to<br>
duplicate the calculation done by the hcurl function:<br>
<br>
define dv = cdiff(v,x)<br>
define dx = cdiff(lon,x)*3.1416/180<br>
define du = cdiff(u*cos(lat*3.1416/180),y)<br>
define dy = cdiff(lat,y)*3.1416/180<br>
display (dv/dx-du/dy)/(6.37e6*cos(lat*3.1416/180))<br>
<br>
But there is no description of hdivg function. I guess hdivg function<br>
could be duplicated using cdiff function as following. Please anybody<br>
tell me if it is correct or not. Thanks!<br>
<br>
define dv = cdiff(v,x)<br>
define dx = cdiff(lon,x)*3.1416/180<br>
define du = cdiff(u*cos(lat*3.1416/180),y)<br>
define dy = cdiff(lat,y)*3.1416/180<br>
display (du/dx+dv/dy)/(6.37e6*cos(lat*3.1416/180))<br>
<br>
Yaqiang Wang<br>
<br>
Chinese Academy of Meteorological Sciences<br>
<font color="#888888"><a href="mailto:yaqiang.wang@gmail.com">yaqiang.wang@gmail.com</a><br>
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</font></blockquote></div><br><br clear="all"><br>-- <br>Jeff Duda<br>Iowa State University<br>Meteorology Graduate Student<br>3134 Agronomy Hall<br><a href="http://www.meteor.iastate.edu/~jdduda">www.meteor.iastate.edu/~jdduda</a><br>