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<p class=MsoNormal><b><font size=2 color=black face=Tahoma><span
style='font-size:10.0pt;font-family:Tahoma;color:windowtext;font-weight:bold'>From:</span></font></b><font
size=2 color=black face=Tahoma><span style='font-size:10.0pt;font-family:Tahoma;
color:windowtext'> wxqc-bounces@lists.gladstonefamily.net [mailto:wxqc-bounces@lists.gladstonefamily.net]
<b><span style='font-weight:bold'>On Behalf Of </span></b>Dave Helms<br>
<b><span style='font-weight:bold'>Sent:</span></b> Thursday, August 18, 2005
10:03 PM<br>
<b><span style='font-weight:bold'>To:</span></b> Discussion of data quality
issues<br>
<b><span style='font-weight:bold'>Cc:</span></b> kenneth.labas@noaa.gov; Nolan
Doesken; jim.allsopp@noaa.gov<br>
<b><span style='font-weight:bold'>Subject:</span></b> Re: [wxqc] Temperature
Measurement Problems</span></font><font color=black><span style='color:windowtext'><o:p></o:p></span></font></p>
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<p class=MsoNormal><font size=3 color=black face="Times New Roman"><span
style='font-size:12.0pt'>Hi Jefferey,<br>
<br>
I looked at your neighbors data and your recent reports. <br>
<a href="http://www.findu.com/cgi-bin/wxpage.cgi?call=CW4066&last=720">http://www.findu.com/cgi-bin/wxpage.cgi?call=CW4066&last=720</a><br>
<br>
Its been warm and the sun is still relatively high inclination for your
latitude which causes at least some elevated temperatures in stations receiving
direct sun, particularly those which have passively aspirated radiation shields
(which is the norm for most weather stations). Russ references a study
made by Gearld Gill (e.g. the "Gill" shield) that documented elevated
temps in passively aspirated shields here: <a
href="http://www.wxqa.com/shields.html">http://www.wxqa.com/shields.html</a><br>
<br>
The other issue you picked up on is the proximity to the trees. Its been
dry in your area, <a href="http://www.drought.unl.edu/dm/monitor.html">http://www.drought.unl.edu/dm/monitor.html</a>,
and outside of the tree canopy, the soil is getting baked dry and holding more
and more summer heat. However in your local area, the combination of
shade and resulting moderated soil temperatures help moderate your local
temperatures. We also see situations where stations in the outter ring of
city suburban regions appear to be (are in fact) cooler than stations closer to
the city heat islands (this is the case with my station with corn fields
to my north and the DC metro concrete jungle to my south). <br>
<br>
So in my opinion, you are very accurately measuring temperature for your local
area. This is exactly the type of micro-climate we want to characterize
with very dense CWOP station network. I know the MADIS QCMS statistics
show your station as having mean temperature too cool, but I believe your
"cool" bias is real so I would not be concerned about the
difference. As your area gets stronger winds and lower sun angles with
the advance of the fall season, your cool bias will be reduced and you will get
a "green check". <br>
<br>
For not knowing much, you seem to have figured out great deal!<br>
<br>
Dave<br>
CW0351<br>
<br>
Jeffrey Mack wrote: <o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=black face=Arial><span style='font-size:
10.0pt;font-family:Arial'><u1:SmartTagType namespaceuri="urn:schemas-microsoft-com:office:smarttags" name="City"><u1:SmartTagType namespaceuri="urn:schemas-microsoft-com:office:smarttags" name="PlaceType"><u1:SmartTagType namespaceuri="urn:schemas-microsoft-com:office:smarttags" name="PlaceName"><u1:SmartTagType namespaceuri="urn:schemas-microsoft-com:office:smarttags" name="place"></u1:SmartTagType></u1:SmartTagType></u1:SmartTagType></u1:SmartTagType>I
recently installed a Davis Vantage Pro2 aspirated weather station and began
collecting data and feeding it to CWOP. So far, my temperature data is not
meeting the CWOP quality goals determined by comparing my measures with
predicted values for my location. The neighborhood we live in has many tall oak
trees and our yard backs up to a wooded forest preserve area. I situated the <st1:City u2:st="on"><st1:place u2:st="on">Davis</st1:place></st1:City>
temperature and humidity sensors on a 5’ post approximately 50 feet from
the edge of the wooded area and about 35’ from our house. The anemometer
is attached to a tv antenna mast on our roof about 30’ feet up. Presently
this site is in full sunlight from approximately 10 AM to about 3:30 PM. In the
morning hours the site is shaded by our house and in the afternoon it is shaded
by the woods.<u1:p></u1:p></span></font><o:p></o:p></p>
<p class=MsoNormal><font size=2 color=black face=Arial><span style='font-size:
10.0pt;font-family:Arial'><u1:p> </u1:p></span></font><o:p></o:p></p>
<p class=MsoNormal><font size=2 color=black face=Arial><span style='font-size:
10.0pt;font-family:Arial'>Our temperature readings are consistently below the
predicted values with a noticeably bigger difference that often occurs
beginning around 12 noon local time. However the nearest other reporting
site (1 ½ miles away), <st1:place u2:st="on"><st1:PlaceName u2:st="on">DuPage</st1:PlaceName>
<st1:PlaceType u2:st="on">Airport</st1:PlaceType></st1:place>, reports
temperature that follow our readings noticeably closer than the predicted
values. How are the predicted data in the analysis calculated? And are my
readings possibly more accurate due to the use of an aspirated temperature
shield vs. nearby stations using non-aspirated shields which may tend to
maintain more heat as the day goes on? Or am I simply being affected adversely
by the proximity of the wooded area. But if that be the case, why is DuPage
closer to my readings than to the predicted readings? <u1:p></u1:p></span></font><o:p></o:p></p>
<p class=MsoNormal><font size=2 color=black face=Arial><span style='font-size:
10.0pt;font-family:Arial'><u1:p> </u1:p></span></font><o:p></o:p></p>
<p class=MsoNormal><font size=2 color=black face=Arial><span style='font-size:
10.0pt;font-family:Arial'>I am curious about how one assesses the quality of a
temperature reading in general. If one measures temperature in an area where
there are numerous trees, is this reading any less accurate than one taken in
area without trees? <u1:p></u1:p></span></font><o:p></o:p></p>
<p class=MsoNormal><font size=2 color=black face=Arial><span style='font-size:
10.0pt;font-family:Arial'><u1:p> </u1:p></span></font><o:p></o:p></p>
<p class=MsoNormal><font size=2 color=black face=Arial><span style='font-size:
10.0pt;font-family:Arial'>Here are links for several days to our data and
analyses:<u1:p></u1:p></span></font><o:p></o:p></p>
<p class=MsoNormal><font size=2 color=black face=Arial><span style='font-size:
10.0pt;font-family:Arial'><u1:p> </u1:p></span></font><o:p></o:p></p>
<p class=MsoNormal><font size=2 color=black face=Arial><span style='font-size:
10.0pt;font-family:Arial'><a
href="http://weather.gladstonefamily.net/qchart/C4066?date=20050817&addnl=KDPA&Add+to+charts=Add+to+charts&.cgifields=addnl">http://weather.gladstonefamily.net/qchart/C4066?date=20050817&addnl=KDPA&Add+to+charts=Add+to+charts&.cgifields=addnl</a><u1:p></u1:p></span></font><o:p></o:p></p>
<p class=MsoNormal><font size=2 color=black face=Arial><span style='font-size:
10.0pt;font-family:Arial'><u1:p> </u1:p></span></font><o:p></o:p></p>
<p class=MsoNormal><font size=2 color=black face=Arial><span style='font-size:
10.0pt;font-family:Arial'><a
href="http://weather.gladstonefamily.net/qchart/C4066?date=20050816&addnl=KDPA&Add+to+charts=Add+to+charts&.cgifields=addnl">http://weather.gladstonefamily.net/qchart/C4066?date=20050816&addnl=KDPA&Add+to+charts=Add+to+charts&.cgifields=addnl</a><u1:p></u1:p></span></font><o:p></o:p></p>
<p class=MsoNormal><font size=2 color=black face=Arial><span style='font-size:
10.0pt;font-family:Arial'><u1:p> </u1:p></span></font><o:p></o:p></p>
<p class=MsoNormal><font size=2 color=black face=Arial><span style='font-size:
10.0pt;font-family:Arial'><a
href="http://weather.gladstonefamily.net/qchart/C4066?date=20050815&addnl=KDPA&Add+to+charts=Add+to+charts&.cgifields=addnl">http://weather.gladstonefamily.net/qchart/C4066?date=20050815&addnl=KDPA&Add+to+charts=Add+to+charts&.cgifields=addnl</a><u1:p></u1:p></span></font><o:p></o:p></p>
<p class=MsoNormal><font size=2 color=black face=Arial><span style='font-size:
10.0pt;font-family:Arial'><u1:p> </u1:p></span></font><o:p></o:p></p>
<p class=MsoNormal><font size=2 color=black face=Arial><span style='font-size:
10.0pt;font-family:Arial'><a
href="http://weather.gladstonefamily.net/qchart/C4066?date=20050814&addnl=KDPA&Add+to+charts=Add+to+charts&.cgifields=addnl">http://weather.gladstonefamily.net/qchart/C4066?date=20050814&addnl=KDPA&Add+to+charts=Add+to+charts&.cgifields=addnl</a><u1:p></u1:p></span></font><o:p></o:p></p>
<p class=MsoNormal><font size=2 color=black face=Arial><span style='font-size:
10.0pt;font-family:Arial'><u1:p> </u1:p></span></font><o:p></o:p></p>
<p class=MsoNormal><font size=2 color=black face=Arial><span style='font-size:
10.0pt;font-family:Arial'><a
href="http://weather.gladstonefamily.net/qchart/C4066?date=20050813&addnl=KDPA&Add+to+charts=Add+to+charts&.cgifields=addnl">http://weather.gladstonefamily.net/qchart/C4066?date=20050813&addnl=KDPA&Add+to+charts=Add+to+charts&.cgifields=addnl</a><u1:p></u1:p></span></font><o:p></o:p></p>
<p class=MsoNormal><font size=2 color=black face=Arial><span style='font-size:
10.0pt;font-family:Arial'><u1:p> </u1:p></span></font><o:p></o:p></p>
<p class=MsoNormal><font size=2 color=black face=Arial><span style='font-size:
10.0pt;font-family:Arial'>I’m sure there’s a lot that I don’t
understand about what is happening here so I will appreciate any help and
suggestions to improve both the quality of data that I am providing and my understanding
of the science.<u1:p></u1:p></span></font><o:p></o:p></p>
<p class=MsoNormal><font size=2 color=black face=Arial><span style='font-size:
10.0pt;font-family:Arial'><u1:p> </u1:p></span></font><o:p></o:p></p>
<p class=MsoNormal><font size=2 color=black face=Arial><span style='font-size:
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style='font-size:10.0pt'><o:p> </o:p></span></font></pre><pre
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style='font-size:10.0pt'><o:p> </o:p></span></font></pre><pre><font
size=2 color=black face="Courier New"><span style='font-size:10.0pt'>_______________________________________________<o:p></o:p></span></font></pre><pre><font
size=2 color=black face="Courier New"><span style='font-size:10.0pt'>wxqc mailing list<o:p></o:p></span></font></pre><pre><font
size=2 color=black face="Courier New"><span style='font-size:10.0pt'><a
href="mailto:wxqc@lists.gladstonefamily.net">wxqc@lists.gladstonefamily.net</a><o:p></o:p></span></font></pre><pre><font
size=2 color=black face="Courier New"><span style='font-size:10.0pt'><a
href="http://pond1.gladstonefamily.net:8080/mailman/listinfo/wxqc">http://pond1.gladstonefamily.net:8080/mailman/listinfo/wxqc</a><o:p></o:p></span></font></pre><pre><font
size=2 color=black face="Courier New"><span style='font-size:10.0pt'><o:p> </o:p></span></font></pre><pre><font
size=2 color=black face="Courier New"><span style='font-size:10.0pt'>The contents of this message are the responsibility of the author.<o:p></o:p></span></font></pre></div>
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