[wxqc] Dewpoints for CW5204 (Ultimeter)

[Dave Helms]

Hi Jerry,

Your siting sounds fine and the sling calibration is great.  However, 
its not uncommon for Ultimeter humidity sensors to run a bit high, I 
know mine does.  Looking at stations RHs in your area:
http://www.findu.com/cgi-bin/wxnear.cgi?call=N0JY-5
.. you are reporting the highest RH of twenty stations.  I would not 
think there is a good reason for your station having elevated RH 
measurements given your location in north central Texas.  On the other 
hand, your humidity measurements are not outragiously high and the 
overall trend is very reasonable.

If you decide to change anything (your RH measurements are pretty good 
right now), I suggest a minor humidity sensor adjustment at the board 
level.  Please refer to this archive thread for adjusting the Ultimeter:
http://pond1.gladstonefamily.net:8080/pipermail/wxqc/2005-July/000345.html


Hope this helps,

Dave
CW0351

Gerald Buxton wrote:

>I too am having trouble with my dewpoint, the analysys saying that it
>needs to be adjusted down about 4 degrees on the average (depending on
>which day you check the analysis).
>
>http://weather.gladstonefamily.net/site/AR194
>
>The Peet solar shielded temp/humidity sensor being new when the error
>began being reported back in October of 2005, I did some checks with a
>sling psychrometer I built using two very similar thermometers.  The
>psychrometer readings support the dewpoint readings of the station. 
>The sensor is mounted on a 5 foot pole 50 feet away from the house in
>over native grasses (or what is left of them due to the winter and
>drought).  Is it possible that the analysis is not accurate due to
>other readings in the area (although the closest readings according to
>the analysis page are 15 to 20 miles away) or do you think my sensor is
>out of whack?
>
>Thank you for any suggestions.
>Jerry 
>AR194 
>N0JY
>
>On Thu, 02 Feb 2006 21:49:47 -0500, Dave Helms wrote:
>
>  
>
>>John,
>>
>>The QCMS analsysis is not perfect, but most of the time its pretty 
>>good.  Despite some anomalies in the analysis, your data still has three 
>>green checks. Whatever crappy stations may be in your vicinity, a good 
>>station is a good station absolutely.  Flags that QCMS applies to a 
>>particular observation and parameter do not necessarily mean that the 
>>data is bad, just something someone using the data may want to take a 
>>second look at.
>>
>>Dave
>>CW0351
>>
>>    
>>
>
>
>
>
>
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