[wxqc] temperature errors

[Gerry Creager]

How far above your compisite roof is the radiation shield?  I'm a bit 
concerned that you're seeing a temperature anomaly because you're seeing 
an indication of the roof's radiated heat.

One potential issue with QC analysis that comparison of nearby stations 
can be when there is a combination of no really nearby stations and 
complex topography leading to QC checks showing a Big Rex X (tm) and 
causing concern.

Have you spot-checked temperatures with a good, calibrated thermometer? 
  That'd be be a good first step.

I like this reference for information on siting on/around structures. 
It's mainly designed to allow adequate siting information for 
mesonet-type installations in urban zones but the information about 
siting temperature and anemometry sensors above rooflines is worth 
reading: 
http://www.wmo.ch/web/www/IMOP/publications/IOM-81/IOM-81-UrbanMetObs.pdf

gerry

dbj at capital.net wrote:
> My new Davis Vantage Pro 2 has been operating since the beginning of 
> August 06.  As shown in the link below, on average, the temperature 
> readings have been about 2 degrees F warmer than most other nearby 
> weather stations, with the greatest difference occurring at night.  As 
> shown below from the weather data quality report for this past day, 
> temps. were up to 9 degrees F warmer at my station. 
> 
> I installed a new temp. sensor during the last week of August.  Davis 
> sent me a replacement after the original one malfunctioned by reading 
> -90 F when the humidity reached 100%.  Do I have another sensor problem, 
> a siting problem or is my location warmer for some reason?  Pictures of 
> my site are available at the link below.  The temp. sensor is five feet 
> above the ground but is located near the edge of a steep bank.    
> 
> Thanks for any help.  David Johnson
> 
> http://weather.gladstonefamily.net/site/C6304?tile=10;days=3#Data
> 
> Date UTC SITE Alt (mb) Temp °F DewPt °F Wind Dir Speed knts
> 08-OCT-2006 0457 CW6304 1028.0 +0.15 *46* *-7.62* 40 -2.41 95 -14 1.7 -1.7
> 08-OCT-2006 0517 CW6304 1028.0 +0.15 *47* *-8.62* 40 -2.73 157 -76 0.9 -0.8
> 08-OCT-2006 0527 CW6304 1028.1 +0.05 *47* *-8.62* 40 -2.40 133 -52 0.9 -0.8
> 08-OCT-2006 0537 CW6304 1027.9 +0.25 *47* *-8.62* 40 -2.40 134 -53 0.9 -0.8
> 08-OCT-2006 0558 CW6304 1027.9 -0.09 *46* *-9.11* 40 -3.52 0 +106 0.0 +0.0
> 08-OCT-2006 0619 CW6304 1027.9 -0.09 *46* *-9.11* 40 -3.84 134 +4 0.9 -0.8
> 08-OCT-2006 0629 CW6304 1027.8 +0.01 *44* *-7.11* 40 -3.12 115 +23 1.7 -1.7
> 08-OCT-2006 0646 CW6304 1027.8 +0.01 *44* *-7.11* 40 -3.43 68 +70 2.6 -2.6
> 08-OCT-2006 0657 CW6304 1027.8 -0.02 *44* *-8.06* 40 -4.78 65 +71 2.6 -2.5
> 08-OCT-2006 0717 CW6304 1027.9 -0.12 *43* *-7.06* 40 -4.38 70 +66 2.6 -2.5
> 08-OCT-2006 0726 CW6304 1027.8 -0.02 *43* *-7.06* 40 -4.38 63 +73 2.6 -2.5
> 08-OCT-2006 0746 CW6304 1027.9 -0.12 *43* *-7.06* 40 -4.38 79 +57 1.7 -1.7
> 08-OCT-2006 0756 CW6304 1027.8 +0.05 *43* *-8.09* 40 -5.11 79 +25 1.7 -1.6
> 08-OCT-2006 0817 CW6304 1027.7 +0.15 *44* *-9.09* 40 -5.51 80 +24 1.7 -1.6
> 08-OCT-2006 0827 CW6304 1027.7 +0.15 *44* *-9.09* 40 -5.51 80 +24 0.9 -0.8
> 08-OCT-2006 0847 CW6304 1027.9 -0.05 *43* *-8.09* 40 -5.11 0 +73 0.0 +0.1
> 08-OCT-2006 0857 CW6304 1028.0 -0.13 *42* *-7.65* 39 -4.77 80 -97 0.9 -0.3
> 08-OCT-2006 0907 CW6304 1028.2 -0.33 *42* *-7.65* 40 -5.06 85 -102 0.9 -0.3
> 08-OCT-2006 0927 CW6304 1028.2 -0.33 *41* *-6.65* 39 -4.62 0 -49 0.0 +0.6
> 08-OCT-2006 1116 CW6304 1028.2 +0.23 *40* *-7.23* 39 -5.49 66 +56 4.3 -4.3
> 08-OCT-2006 1126 CW6304 1028.2 +0.23 *40* *-7.23* 38 -5.22 78 +44 3.5 -3.4
> 08-OCT-2006 1146 CW6304 1028.7 -0.27 *41* *-8.23* 40 -6.49 74 +48 0.9 -0.8
> 08-OCT-2006 1156 CW6304 1028.6 +0.05 *42* *-8.66* 40 -5.39 32 +68 0.9 -0.6
> 08-OCT-2006 1217 CW6304 1028.6 +0.05 *42* *-8.66* 40 -4.56 0 +68 0.0 +0.2
> 08-OCT-2006 1227 CW6304 1028.7 -0.05 *42* *-8.66* 40 -5.11 0 +68 0.0 +0.2
> 08-OCT-2006 1247 CW6304 1028.6 +0.05 *43* *-9.66* 41 -6.85 24 +76 0.9 -0.6
> 08-OCT-2006 Errs CW6304 0/95 37/95 0/95 0/95 0/95
> 08-OCT-2006 Smry CW6304 -0.2 0.38 -6 2.31 -1 3.42 +1 80 -1.4 1.4
> 08-OCT-2006 Week CW6304 -0.8 0.61 -3 2.81 -1 1.97 +5 68 -2.1 2.1
> 
> 
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-- 
Gerry Creager -- gerry.creager at tamu.edu
Texas Mesonet -- AATLT, Texas A&M University	
Cell: 979.229.5301 Office: 979.458.4020  FAX 979.862.3983
MAIL:  AATLT, 3139 TAMU
Physical: 1700 Research Parkway, Suite 160,
College Station, TX 77843-3139