[wxqc] RE: Temperature Measurement Problems (Jeffrey Mack)

[Paul de Muinck]

Jeffery,

I also have the Vantage Pro2 with aspirated shield and my temperatures, 
especially when over about 88 deg are consistently below the nearby 
stations (closest is about 3 miles away) as well as the analysis results 
by about 2-4 deg.... The closer the ambient temperature gets to 100, the 
greater the error. The VP2 is mounted about 8 feet off the ground and 
meets most of the recommended setup for distance from pavement, 
structures and is located over dirt and grass.

My station is about 25feet from the house and over 50 feet from the tall 
trees. My dew point in the daytime is about 3-5 deghigher than other 
nearby stations but I usually attribute that to 3 large (> 3/4 acre) 
ponds in the neighborhood within 500-1000 ft of the VP2.

Since I've only had the station a couple of months, I don't have 
analysis for the colder months...

Example of a data with high temps....

http://weather.gladstonefamily.net/qchart/C3782?date=20050813


>
>Jeffrey Mack wrote: 
>
>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 Davis 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.
>
> 
>
>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),
>DuPage Airport, 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? 
>
> 
>
>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? 
>
>
> 
>
> 
>
> 
>
> 
>
> 
>
> 
>  
>
>