<div dir="ltr"><div>I am not sure about "mositure divergence" on WRF grids. To my knowledge, there is no NCL function to compute divergence on some arbitrary WRF grid. As noted by Evelyn Grell in her comments about vorticity, the function would have to make use of map factors.<br><br></div><div>The example you refer to interpolates the u,v components on a WRF (curvilinear) grid to a rectilinear grid of approximately the same resolution. The divergence is calculated on the rectilinear grid using uv2dv_cfd and the reinterpolated back to the WRF grid. As noted in the previous response, this approach is likely adequate for graphical purposes. However, the correct way is to calculate the divergence on the original grid.<br><br></div><div>The following is an example<br></div><div><br><a href="https://www.ncl.ucar.edu/Applications/ESMF.shtml">https://www.ncl.ucar.edu/Applications/ESMF.shtml</a><br></div><div>Example 29<br><br><a href="https://www.ncl.ucar.edu/Applications/Scripts/ESMF_regrid_29.ncl">https://www.ncl.ucar.edu/Applications/Scripts/ESMF_regrid_29.ncl</a><br><br><br></div><div><br> <br></div><div><br></div>Example 5<br><br></div><div class="gmail_extra"><br><div class="gmail_quote">On Fri, Nov 4, 2016 at 1:37 PM, Deng Xu <span dir="ltr"><<a href="mailto:dengxu89@hotmail.com" target="_blank">dengxu89@hotmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
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<p class="MsoNormal">To whom it may concern,<u></u><u></u></p>
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<p class="MsoNormal">Hi, I found some information about calculating moisture divergence in WRF in your previous ncl-talk mailing list. The link is:
<a href="https://www.ncl.ucar.edu/Support/talk_archives/2010/1066.html" target="_blank">https://www.ncl.ucar.edu/<wbr>Support/talk_archives/2010/<wbr>1066.html</a>.<u></u><u></u></p>
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<p class="MsoNormal">I wonder why, after calculating the divergence, I have to <em>
<span style="font-family:"Calibri",sans-serif;font-style:normal">interpolate back to the original WRF coordinates. Is there any example scripts?<u></u><u></u></span></em></p>
<p class="MsoNormal"><em><span style="font-family:"Calibri",sans-serif;font-style:normal"><u></u> <u></u></span></em></p>
<p class="MsoNormal"><em><span style="font-family:"Calibri",sans-serif;font-style:normal">Hope you could help me!<u></u><u></u></span></em></p>
<p class="MsoNormal"><em><span style="font-family:"Calibri",sans-serif;font-style:normal"><u></u> <u></u></span></em></p>
<p class="MsoNormal"><em><span style="font-family:"Calibri",sans-serif;font-style:normal">Thank you in advance!<span class="HOEnZb"><font color="#888888"><u></u><u></u></font></span></span></em></p><span class="HOEnZb"><font color="#888888">
<p class="MsoNormal"><em><span style="font-family:"Calibri",sans-serif;font-style:normal">Xu Deng</span></em><i><u></u><u></u></i></p>
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