[wxqc] Dew Point Error for CW6532 Tucson

[John James]

...days passed......

Okay, I read the document, and another that was mentioned yesterday. 
Both are somewhat helpful, but neither really does any weighting. In 
the CWOP document, I can play with the location of my temp / rain 
sensor and just about get an equal score regardless of which option I 
choose. The Vantage Pro 2 is not a unimount system:  I can separately 
mount the anemometer up on the roof by itself. If I do that, however, 
I still leave my temp / rain sensor in the shadow of some trees - 
probably fine for temp, but definitely shorting me when it comes to 
most rain situations. I can move the sensor to the roof and probably 
get a great rain figure, but then have to deal with the roof 
affecting the temp readings.

So, here's my practical question: currently, most of my readings are 
wrong, and to make any fix I either need to buy the property next 
door (very pricey!), or I need to buy some weather hardware. I could 
buy another wireless transmitter and move the anemometer to the roof 
by itself. I could buy a fan / power unit and make my temp with 
radiation and UV shielding and make it fan aspirated. Which would be 
preferrable?

//John


At 04:51 AM 10/4/2006, you wrote:
>John,
>
>Yep, that is the problem with a unimount system.  Precip and temperature
>are probably the most valuable for climate and hydrologic
>considerations.  Wind and temperatures are more important for weather
>prediction (modelers need "good" surface winds, e.g. not buried in the
>canopy).   We recommend that people put their temperature and rain gauge
>near 2 meters/5 feet and the anemometer at 10 meters/33 feet or above
>the canopy, obviously; this implied separating the sensor package.
>
>For folks who must compromise (almost everyone does), we have a table in
>the CWOP Guide that considers typical siting option limitations that
>home owners encounter:
>http://mywebpages.comcast.net/dshelms/CWOP_Guide.pdf
>
>
>Dave
>CW0351
>
>John James wrote:
>
> > At 08:13 PM 10/3/2006, you wrote:
> >
> >>
> >> The first thing that catches my eye is that you have the temp/dpt
> >> attached to a 6 ft. sensor from your rooftop (not familiar with the
> >> term parapet, so maybe I'm wrong). While this is fine for the
> >> anemometer and even the rain gauge, the temperature/dpt sensors
> >> should be located at 2m off the ground (5-6 feet). Very sharp
> >> inversions can set up at night, on the order of 5-10F within 30-40
> >> feet of the surface, especially where terrain and standing water
> >> bodies are an issue. Likely you're sampling a "different airmass"
> >> above your roofline than you would be closer to ground level.
> >>
> >> Evan
> >>
> >>
> >
> >
> > This brings up something I've been wrestling with a bit. I have a
> > station up at my cabin that has been giving incorrect readings. I have
> > a two story house and a somewhat wooded area in both front and back of
> > my house. I don't have a very good clearing for wind, and was going to
> > move the anemometer to the roof, but I don't think I'm getting good
> > rainfall readings either due to the trees. I was thinking of moving
> > the entire station to the roof, but knew that would alter the other
> > readings. The unit is a Vantage Pro 2 Plus. I get the feeling I'm
> > wrestling with which measurement I want to be more incorrect.
> >
> > //John
> >
> >
> > 
> ------------------------------------------------------------------------------
> > John W. James
> > CW4661, CW4663
> > Web:  < http://www.jameshillfarm.com/>
> >
> > Current weather conditions:  <IMG
> > SRC="http://www.jameshillfarm.com/images/WeatherStripJamesHillFfarm.jpg">
> >
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---------------------------------------------------------------
John James
mail:  jjames at jameshillfarm.com  <mailto:jjames at jameshillfarm.com>
Current 
weather:  http://www.jameshillfarm.com/images/WeatherStripJamesHillFarm.jpg