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<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>Apologies to those who know this better
than I do, but this is an interesting question…<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>Unless you do something fancy, the WRF
outputs instantaneous grid-point values, regardless of your output
interval. Those values are filtered non-trivially by some function of
implicit and explicit diffusion in the model (think physics, damping, time and
space discretization, etc). Therefore there is no one answer to your
question. <o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>In practice (I believe) most people just
compare directly to 10-min averaged wind obs (WMO standard), or 2-min averaged
wind obs (USA) but in my opinion 2 minutes is usually too short to be fair.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>One approach to getting at the averaging in
the model is through data assimilation and statistical consideration of
observation error levels when the error may be dominated by representativeness
error (difference between scales represented in obs and model). Others
have looked in spectral space to get an idea of the averaging scales.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>The other thing that you might consider,
if you have the data to do it, is to compare WRF forecasts with obs averaged over
many different time lengths (or alternatively band-pass filtered). Then
you can get a more complete picture of what time scales it can or cannot
predict with skill, and decide whether it is doing what you hope.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>That said, I’d be interested in
hearing any other comments from the community and especially our verification
gurus – is there any “conventional” wisdom or rules of thumb
that folks are using or that have recently shown promise, empirically?
Have I missed something?<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>Sorry that there is no simple answer.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>Josh<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
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face="Times New Roman"><span style='font-size:12.0pt'>
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<p class=MsoNormal><b><font size=2 face=Tahoma><span style='font-size:10.0pt;
font-family:Tahoma;font-weight:bold'>From:</span></font></b><font size=2
face=Tahoma><span style='font-size:10.0pt;font-family:Tahoma'>
wrf-users-bounces@ucar.edu [mailto:wrf-users-bounces@ucar.edu] <b><span
style='font-weight:bold'>On Behalf Of </span></b>Juan Gonzalez<br>
<b><span style='font-weight:bold'>Sent:</span></b> Tuesday, January 26, 2010
12:33 PM<br>
<b><span style='font-weight:bold'>To:</span></b> wrf-users@ucar.edu<br>
<b><span style='font-weight:bold'>Subject:</span></b> [Wrf-users] Comparing U,V
10 meters to observations</span></font><o:p></o:p></p>
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<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>Hi everyone,<o:p></o:p></span></font></p>
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<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'><o:p> </o:p></span></font></p>
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<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>I am interested on validating the WRF 10m wind forecast with
observational data. I would like to know what is the corresponding average
scale for the WRF 10m winds, that is, do the correspond to 1-minute, 10-minute
average winds or what kind of average, if any?<o:p></o:p></span></font></p>
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<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'><o:p> </o:p></span></font></p>
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<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>My WRF configuration outputs wind every 3 hours.<o:p></o:p></span></font></p>
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<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'><o:p> </o:p></span></font></p>
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<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>Thanks for your help, <o:p></o:p></span></font></p>
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<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>Juan Gonzalez <br clear=all>
<br>
-- <br>
Juan O. Gonzalez<br>
Research Assistant - Caribbean Integrated Coastal Ocean Observing System<br>
<br>
Graduate Student - Physical Oceanography<br>
Marine Sciences Department<br>
University of Puerto Rico - Mayaguez Campus<o:p></o:p></span></font></p>
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