[wxqc] QC Errors for C4227

[dshelms at comcast.net]

Hi Dennis,

I agree 100% with Bob.  The ideal shield allows "ambient" (mixed atmosphere) air to blow across the temperature probe while denying the sun's rays from striking (directly or even indirectly) the probe.  
The WS-2310 "Shield" allows almost NO ventilation, as shown here:
http://www.lacrossetechnology.com/products/pwc/sensors/2310_thermo.html
... while the WS-2310 shield stops direct sunlight, it is a very poor shield for allowing ambient or mixed air to be sampled since the air is trapped inside their stock "cone" shield.  On sunny days, this raises your maximum temperature 5-10 F degrees above the actual maximum temperature you should be measuring.

The best way to ensure the temperature and humidity probes are well ventitated  is to have a Gill type "bee-hive" shield.  The Gill shield is a series of nearly flat disks stacked vertically (painted white (aluminum) or made of white material (plastic) to reflect sunlight) which a 1.5 inch seperation between each disk, with the bottom to middle disks hollowed out in the center to accept the temperature and humidity sensors.    

Passively aspirated (no fan) Gill shields work well, but the Cadilac of radiation shields is an actively aspirated shield which pulls amibient air across the temperature and RH probes using a fan (often solar powered as active aspiration is most helpful during the day). 

Hope this helps,

Dave
CW0351


> Dennis,
> 
> I have a WS-2310 and the shield that comes with it is a poor excuse
> for a shield, and does not protect against direct sun influence.   I
> repositioned mine a number of times but ended up building a small
> shield and placing the sensor in a large thicket of very tall bushes
> to stop the direct sun temperature spikes...
> 
> This page discusses a number of Radiation shield suggestions and if
> your sensor has to be exposed to direct sun i would highly recommend
> one of them...
> http://www.wxqa.com/shields.html
> 
> I also have heard of folks buying the Davis Radiation shield and
> removing the plastic enclosure completely from the 2310 sensor and
> placing the circuit board in that sheild...
> http://www.weather-watch.com/smf/index.php/topic,8199.msg59490.html#msg59490
> 
> -Bob
> 
> On 10/21/05, Dennis L. Carr <dennis.carr at supportnow.org> wrote:
> > I have a WS2310 Weather Station. It's hard wired using CAT 5 cable and also 
> has wireless sensors. I run the latest version of Heavy Weather and WUHU for 
> data collection and submission. The wind sensors are mounted on a pole 10 feet 
> above my roof. The rain gauge is mounted 2 feet off the ground on a pole about 
> 30 feet in fron of my home and the thermo-hygro sensor is mounted near the rain 
> gauge on a 3 foot pole above the ground. This sensor has a cover on it which I 
> assumed to be a radiation shield. Although I think it's just a weather shield???
> >
> > I'm getting temperature and dew point errors and the QC page suggests I need a 
> radiation shield for the thermo-hygro sensor. I have another digital thermometer 
> next to it and it reads with in a few tenths of the WS2310 thermo-hygro sensor 
> and I check the rain and compare with a manual gauge and I compares favorably. 
> The barometer and wind seem to be within tolerance.
> >
> > Do I really need a radiation shield? Will this correct the errors?
> > WS2310 Specs - http://www.heavyweather.info/new_english_us/index.html
> >
> > Dennis L. Carr
> > C4227
> > http://bellyacres.supportnow.org/weather/currentweather.htm
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