<html><head></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><div><span class="Apple-style-span" style="font-size: 18px;">Hi TJ,</span></div><div><span class="Apple-style-span" style="font-size: 18px;"><br></span></div><div><span class="Apple-style-span" style="font-size: 18px;">I admit I've never understood this resource very well. Dave Brown is out of the office, but here's an explanation from him (modified slightly to make sense in this context) that he sent to another user:</span></div><div><span class="Apple-style-span" style="font-size: 18px;"><br></span></div><div><span class="Apple-style-span" style="font-size: 18px;">By default, the vector direction is mapped into the coordinate space defined by the coordinate variables. This is appropriate for horizontal vectors drawn on a map, but not for vectors in a vertical space where the Y axis and the X Axis have completely unrelated units. To fix this you should set the resource vcMapDirection to False. However, it also has the effect of always making the positive Y direction from bottom to top. If the vertical component is positive from top to bottom of the atmosphere, then you will need to multiply the vertical component by -1.0 to get the result you are looking for.</span><div><span class="Apple-style-span" style="font-size: 18px;"><br></span></div></div><div><span class="Apple-style-span" style="font-size: 18px;">--Mary</span></div><div><span class="Apple-style-span" style="font-size: 18px;"><br></span></div><div><br></div><div><div>On Aug 3, 2011, at 11:54 PM, wxtofly wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite">
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<font size="+1"><tt>I am confused by this resource as the examples
are not consistent with its use and I don't really understand
what it does in the absence of an underlying map as on the
attached windgram plots.<br>
<br>
I have attached two of my windgrams, one produced without any
mention of vcMapDirection which therefore would use the true
default, and the other with<br>
uv_res@vcMapDirection=false. As you can see they are nearly but
not exactly identical. (gwenview or something similar next
prev to rock between them)<br>
<br>
On the NCAR site, the 1 special example meteo.ncl uses
uv_res@vcMapDirection=false. The 5 wrf_meteo(1-5).ncl omit the
resource. Which is "correct." <br>
What would I expect the effects to be?<br>
<br>
Thanks for you help.<br>
<br>
TJ Olney<br>
<br>
</tt></font>
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