[wxqc] New to QC - Some help interpreting this please

[Stephen Longmire]

It is on the roof because that’s the only place not affected by landscaping.
My trees/bushes are short, but they pretty much ruled out any place in the
yard.

 

  _____  

From: wxqc-bounces at lists.gladstonefamily.net
[mailto:wxqc-bounces at lists.gladstonefamily.net] On Behalf Of Victor Engel
Sent: Sunday, July 16, 2006 23:21
To: Discussion of weather data quality issues
Subject: Re: [wxqc] New to QC - Some help interpreting this please

 

I'm new to all this stuff, but I'll chime in anyway. Hence the following
will be my opinion.

Your interpretation is correct, except that I would say "greater than
analysis" rather than "greater than it should be". I think it's wrong to
assume the analysis is, by definition, correct for your location. I would
use it as a guideline. My setup, for example, is in my back yard. Today I
spent a lot of time watering the lawn (which is too tall) and I also have a
fish pond. So I would EXPECT my humidity to be higher than analysis because
I have a lot of sources of evaporation and transpiration near my sensor. 

Also, if you read the QC reports and their supporting documents carefully,
you will notice that they don't want you to make any adjustments if you are
within 3 mb of the analysis barometric pressure. Also see the guidelines for
the best conditions for adjusting your barometer reading. Those conditions
have not yet materialized since I've installed my station. 

I would also recommend you go to your summary page. There is a giant green
checkmark for each item if your data is OK, according to the analysis. You
get a red X if there is a problem. Use those to see if you're within
tolerances. 

I'm curious why you have the rain gauge on the roof. A source of error for
rain is wind, and the peak of the roof has more wind than your yard would.

On 7/16/06, Stephen Longmire <slongmire at houston.rr.com> wrote:

 

 


Date 

UTC 

SITE 

Alt (mb) 

Temp °F 

DewPt °F 

Wind Dir 

Speed knts


16-JUL-2006 

Week 

CW6132 

-0.5 

0.76 

+2 

1.52 

-2 

1.06 

-4 

73 

+0.1 

1.3


 

 

 

 

 

 

 

 

 

 

 

 

 

 

I have been receiving QC reports for about two weeks now, and while I THINK
I understand this report, I'd like a little confirmation, and
recommendations if I need to do anything with my station.

 

>From this I glean that last week my station barometer averaged 0.5 mb
greater that it should have, the temperature 2 degrees lower, the dew point
two degrees higher, etc. The text that accompanies this report says that
errors are shown in boldface, and none of these was bold. Does this mean
that my data, although different from the expected means, is still within
tolerance? 

 

My sensors for temperature and humidity are in a non-aspirated radiation
shield under a very large crepe myrtle tree at ~ 15ft above ground level.
This was the only location on my property that would not have been shielded
behind a 10 ft high fence or the house itself, and that was not out in the
direct sun or on the roof. The barometer is inside the console in an air
conditioned second floor room. (Although this is an 80+ yo house and FAR
from air tight!) The anemometer and rain gauge are on a pole mount on the
roof – with the rain gauge ~ 4 ft above the peak and the anemometer ~12 ft.
I realize that these locations don't conform to the ideal guidelines, but
they are in fact the best compromise given the layout of my property near
downtown Houston.

 

Oh, by the way, the station is a Texas Weather Instruments WR-25, which was
sent back to their factory about 1 yr ago for calibration and replacement of
the anemometer assembly and rain gauge (as both were > 10 yrs old). This is
a wired station and is on its own APC UPS power supply.

 

Thanks,

 

Steve Longmire


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