<div dir="ltr">Hi John,<div><br></div><div>I think you have a units problem. According to the documentation (<a href="http://www.ncl.ucar.edu/Document/Functions/WRF_arw/wrf_user_vert_interp.shtml">http://www.ncl.ucar.edu/Document/Functions/WRF_arw/wrf_user_vert_interp.shtml</a>), the vertical coordinate type of "ght_agl" is in units of [km]. Try running your code again with height_levels = (/ 1.0, 2.0, 3.0, 4.0 /) and see if that fixes it. I have no idea why they wanted the interp_levels argument in units of [km], but that's what the underlying Fortran routine expects.</div><div><br></div><div>If that doesn't help, I'll try to dig in a little further.</div><div><br></div><div>Hope this helps,</div><div><br></div><div>Bill</div></div><div class="gmail_extra"><br><div class="gmail_quote">On Tue, May 2, 2017 at 9:03 AM, Trostel, John M. <span dir="ltr"><<a href="mailto:john.trostel@gtri.gatech.edu" target="_blank">john.trostel@gtri.gatech.edu</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 style="font-family:Calibri,Arial,Helvetica,sans-serif;font-size:16px">I am trying to use the wrf utility "wrf_user_vert_interp" to interpolate some WRF output to heights AGL<br>
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<blockquote style="font-family:Calibri,Arial,Helvetica,sans-serif;font-size:16px;margin:0px 0px 0px 40px;border:none;padding:0px">
<div> u = wrf_user_getvar(a,"ua",-1) ; u averaged to mass points</div>
<div> v = wrf_user_getvar(a,"va",-1) ; v averaged to mass points</div>
<div> z = wrf_user_getvar(a, "z",-1) ; grid point height</div>
<div> printVarSummary(u)</div>
<div> printVarSummary(v)</div>
<div><br>
</div>
<div>; The specific height levels that we want the data interpolated to.</div>
<div>; And interpolate to these levels</div>
<div> height_levels = (/ 1000., 2000., 3000., 4000. /) ; height levels to plot - in meter</div>
<div> nlevels = dimsizes(height_levels) ; number of height levels</div>
<div><br>
</div>
<div> u_plane = wrf_user_vert_interp( a,u,"ght_agl",height_levels,<wbr>False)</div>
<div> v_plane = wrf_user_vert_interp( a,v,"ght_agl",height_levels,<wbr>False)</div>
</blockquote>
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<br>
When I try to plot the new wind vectors at these levels I get the error:<br>
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<div style="font-family:Calibri,Arial,Helvetica,sans-serif;font-size:16px">
"warning:VectorPlotInitialize: no valid values in vector field; VectorPlot not possible"<br>
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<br>
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and get an empty vector plot (the contour plot is fine). Any clue why this happens?<br>
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<br>
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<blockquote style="font-family:Calibri,Arial,Helvetica,sans-serif;font-size:16px;margin:0px 0px 0px 40px;border:none;padding:0px">
<div>do level = 0,nlevels-1 ; LOOP OVER LEVELS</div>
<div><br>
</div>
<div> height = height_levels(level)</div>
<div> height = height*3.2084</div>
<div><br>
</div>
<div> ; Add some level into to the plot</div>
<div> res@PlotLevelID = height + " ft"<br>
</div>
<div><br>
</div>
<div> opts = True ; Set some Basic Plot options<br>
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<div><br>
</div>
<div> ter = wrf_user_getvar(a,"HGT_M",0) ; Read the variable to memory</div>
<div> ter_zoom = ter(y_start:y_end,x_start:x_<wbr>end) ; need (:, for z-data</div>
<div><br>
</div>
<div> ter_zoom = ter_zoom*3.2084</div>
<div><br>
</div>
<div> ter_zoom@units = "feet"</div>
<div><br>
</div>
<div> opts@cnFillOn = True ; Create a color fill plot</div>
<div> opts@ContourParameters = (/ 0., 10000., 200. /) ; Set the levels</div>
<div><br>
</div>
<div> contour_zoom = wrf_contour(a,wks,ter_zoom,<wbr>opts)</div>
<div> delete(opts)</div>
<div><br>
</div>
<div> ; Plotting options for Wind Vectors </div>
<div> opts = res </div>
<div> opts@FieldTitle = "Wind" ; overwrite Field Title</div>
<div> opts@NumVectors = 50 ; wind barb density</div>
<div> vector = wrf_vector(a,wks,u_plane(it,{<wbr>height_levels(level)},y_start:<wbr>y_end,x_start:x_end),v_plane(<wbr>it,{height_levels(level)},y_<wbr>start:y_end,x_start:x_end),<wbr>opts)</div>
<div> delete(opts)</div>
<div><br>
</div>
<div><br>
</div>
<div> ; MAKE PLOTS </div>
<div> plot = wrf_map_overlays(a,wks,(/<wbr>contour_zoom,vector/),pltres,<wbr>mpres)</div>
<div><br>
</div>
<div><br>
</div>
<div> end do ; END OF LEVEL LOOP</div>
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<br>
<br>
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<p><br>
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<div id="m_6156552649197808351Signature">
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--
<div>John Trostel<br>
Director - Severe Storms Research Center<br>
Georgia Tech Research Institute<br>
Atlanta, GA 30332-0857</div>
</div>
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