[wxqc] Baraometer quality problems

[Gerry Creager N5JXS]

Howdy, John,

John Yurciw wrote:
> Gerry,
> 
> Thanks for the info, to answer some of your questions.....
> 
> What's the siting conditions at your location?  The station is located 
> in the middle part of my yard, on about an acre of ground around it and 
> it's all grass.

Good location!

> Where's your barometer sensor installed?  At the weather station in the 
> yard (It's a Davis Vantage Pro2 system)
> In the station Inside a tightly sealed house?  Not sealed but protected
> Outside in the instrument? Yes.

Shouldn't be a problem.  What's the instrument age?  Have you looked at 
calibration against an aneroid barometer?

> How'd you determine your elevation?  Using TopoZone maps
> GPS?  No, I do not have a GPS unit.
> What were the horizontal and vertical datums on the topo map? Not sure 
> the answer for this one, I just used the elevation contours shown on the 
> map

I'll look at the appropriate topozone maps, and if I've questions, I can 
ask their chief mapmaker.  We work on a couple of projects together.  I 
believe the vertical datum is NGVD29, which may have some differences 
with NAVD88.  These could be at variance.

> Using the CWOP info page for your station, does the location and height 
> correspond appropriately?
> You mention you've got the station altitude set at 171 meters but the 
> site info page says 161 meters. I changed this recently, using the 
> TopoZone map I deterimed that I think the elevation should be higher at 
> 171 meters.

OK.  A 2-3 hPa difference suggests you're at a different height than 
reported, that you're not reporting altimeter pressure, or that you may 
have an instrument error, based on the answers so far.

gerry
> ----- Original Message ----- From: "Gerry Creager N5JXS" 
> <gerry.creager at tamu.edu>
> To: "Discussion of weather data quality issues" 
> <wxqc at lists.gladstonefamily.net>
> Sent: Sunday, March 12, 2006 1:22 AM
> Subject: Re: [wxqc] Baraometer quality problems
> 
> 
>> I'm actually much more fascinated by your excursions in temperature 
>> and dewpoint.  You're showing some wide swings, despite Dave Helms' 
>> recent comments on frequent data insertion into the system.
>>
>> Regarding your barometric pressure: What's the siting conditions at 
>> your location?  Where's your barometer sensor installed?  Inside a 
>> tightly sealed house?  Outside in the instrument?  How'd you determine 
>> your elevation?  GPS?  If GPS, what datum was entered?  How did you 
>> obtain a value (there are real issues with simple averaging although 
>> that beats a single spot value)?  Topo map?  What were the horizontal 
>> and vertical datums on the topo map?  Using the CWOP info page for 
>> your station, does the location and height correspond appropriately?  
>> You mention you've got the station altitude set at 171 meters but the 
>> site info page says 161 meters.
>>
>> gerry
>>
>> John Yurciw wrote:
>>
>>> When I get my daily "Weather data quality report",  my */Alt(mb) 
>>> /*readings have consistantly been on the high side, about +2.00 to 
>>> +2.78 and even +2.99. All my other reporting data is fine. My 
>>> question is, do I need to check the elevation setting on my Davis 
>>> Vantage Pro2? If I have this set incorrectly would this be the reason 
>>> that I am getting the error readings from Weather Quality? I 
>>> currently have it set at 171M Thanks in advance for the help
>>> John
>>> http://www.findu.com/cgi-bin/wxpage.cgi?call=CW4264
>>>
>>>
>>> ------------------------------------------------------------------------
>>>
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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
>> Office: 1700 Research Parkway Ste 160, TAMU, College Station, TX 77843
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> 
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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
Office: 1700 Research Parkway Ste 160, TAMU, College Station, TX 77843