[wxqc] Balancing Daytime and Night Temperature Readings

[Gerry Creager]

Realize that siting can affect this, and siting takes on a lot of 
considerations.  It's possible that your readings reflect a valid 
microclimate for where you're located.  Seeing errors in this analysis 
doesn't automatically imply that your system is giving bad readings.  It 
does give you the opportunity to determine if there's something worth 
changing, or to satisfy yourself that it really is all OK.

For what it's worth, MY report from last night looks like this:
    DATE     UTC   *   ALT    * POT TEMP *  DEW PNT *    DD    *    FF
                   *   (MB)   *  (DEG F) *  (DEG F) *   (DEG)  *   (KNT)
21-APR-2007 1320  *1018.(-0.4)*  51(7.92)*  49(8.49)*111.(13.7)*3.48(-1.7)
21-APR-2007 1335  *1018.(-0.4)*  51(7.92)*  49(8.49)*108.(16.7)*3.48(-1.7)
21-APR-2007 1350  *1018.(-0.5)*  51(7.92)*  49(8.49)*120.(4.68)*2.61(-0.9)
21-APR-2007 1405  *1018.(0.06)*  52( 9.5)*  50(9.86)*113.(9.36)*2.61(1.25)
21-APR-2007 1420  *1018.(-0.2)*  53( 8.5)*  51(8.87)*141.(-18.)*2.61(1.25)
21-APR-2007 1435  *1018.(-0.2)*  54( 7.5)*  52(7.88)*131.(-8.6)*3.48(0.38)
21-APR-2007 Errs  *   0/96   *  10/96   *  10/96   *   0/96   *   0/96
21-APR-2007 Smry  *0.02(0.26)*3.64(2.59)*3.92(2.06)*17.7(49.4)*0.94(1.56)

There's not much wrong with my instrument, although it's heading in for 
a firmware update and new sensor module as it's a test unit from Vaisala...

gerry

Geoffrey Dick wrote:
> QUESTION: How to reduce the offset between Day and Night Temperature? 
> 
> Has anyone on this reflector played with the temperature radiation
> shield to balance the daytime and night temperature reading errors? 
> 
> My overnight readings seem to be consistantly accurate, according to 
> the CWOP analysis.  The daytime error -1.3 degrees from the night time
> temperature.   I have done everything I could to locate the sensor in 
> an ideal location in an urban setting.
> 
> Now I am down to fine-tuning things.   The radiation shield is made 
> of a white plastic, and I thought it might help to increase the 
> daytime reflectivity by covering the exposed surface with aluminum 
> foil strips in such a manner that it would not block the flow of air.  
> 
> I have tried using aspiration, but that yielded only limited results
> So now I am game for trying something different.
> 
> Who can comment on their expierence with adjusting the reflectivity 
> of the radiation shield with coloration paint, or metalic coatings? 
> 
> 
> Kind regards,
> 
> Geoffrey Dick
> Winter Park, FL
> Wx Station AS-140 / WA4IKQ
> 
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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
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