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<p>Hi, Dennis,</p>
<p>Thank you for the detailed explanation. <br>
</p>
<p>Ming<br>
</p>
<div class="moz-cite-prefix">On 11/1/19 10:51 AM, Dennis Shea wrote:<br>
</div>
<blockquote type="cite"
cite="mid:CAOF1d_4+9kkjGt5aw928R=9Ut2t0Y0zXoyP82dLUhafgeQu-vQ@mail.gmail.com">
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<div>Generally, for visual purposes, people ignore the fact that
a new grid location would technically require a rotation [rot]
of the interpolated u,v:</div>
<div><br>
</div>
<div> U = ui*cos(rot) + vi*sin(rot) ; ui,vi are
interpolated values<br>
</div>
<div> V = -ui*sin(rot) + vi*cos(rot) ; U,V are after
rotation<br>
</div>
<div><br>
</div>
<div> Generally, the new grid is of about the same resolution so
the rotation angle is 'small'.<br>
</div>
<div>--</div>
<div>If deemed essential, it may be best to <br>
</div>
<div>[a] compute the scalar quantities vorticity and divergence
on the source grid; <br>
</div>
<div>[b] interpolate the scalar quantities to the new grdi; <br>
</div>
<div>[c] derive the rotational [Ur, Vr] and divergent [Ud, Vd]
wind components; <br>
</div>
<div>[d] combine derived components.</div>
<div><br>
</div>
<div> [Ur, Vr] <=== derive from interpolated vorticity</div>
<div> [Ud,Vd] <=== derive from interpolated divergence</div>
<div><br>
</div>
<div> U = Ur + Ud</div>
<div> V = Vr + Vd</div>
<div><br>
</div>
<div><br>
</div>
</div>
<br>
<div class="gmail_quote">
<div dir="ltr" class="gmail_attr">On Fri, Nov 1, 2019 at 9:22 AM
Ming Chen via ncl-talk <<a href="mailto:ncl-talk@ucar.edu"
target="_blank" moz-do-not-send="true">ncl-talk@ucar.edu</a>>
wrote:<br>
</div>
<blockquote class="gmail_quote" style="margin:0px 0px 0px
0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">Hi,<br>
<br>
If I remapp winds on regular lat/lon grids to lambert
projection grids, <br>
the U and V components on the lambert projection grid should
be <br>
grid-relative or they still remain earth-relative?<br>
<br>
Thanks.<br>
<br>
Ming<br>
<br>
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</blockquote>
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</blockquote>
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