Author Topic: their quality standards  (Read 4647 times)

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Offline Aardvark

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their quality standards
« on: February 20, 2010, 12:39:07 PM »
I have been looking at the quality checks on my submission (CW0005).  I have been fine with the exception of it claiming that my pressure sensor needs calibration.  I don't think it does, but their checks got to be wrong.

I have three consoles (1 being an envoy).  One is in the kitchen doing nothing but letting me know how awful it is outside,  the Envoy is in the basement with the main weather computer and the one by the computer is hooked to the IP weatherlink

So.. the pressure looks close to anyone that I can find around here with a personal station with weatherunderground, I have checked my elevation, and it is right .  I used GPS and the topographic maps.  Then I set the pressure to someone near me that generally looks good and that didn't make any difference.

I then went to the other computer and had it start sending data while I turned off the Weatherlink IP one from sending data and still they claim things to be amiss.  So the local NOAA station is 1.5 miles a way  or so they claim... and I see that cwop doesn't agree with them either.   

I am thinking that something is wrong here and I can't find it.  The geographical coordinates are the same and haven't changed or been changed in the software or on the station.  The elevation I set to what CWOP claims and that doesn't make a difference.   

I need "Mr. Obvious"  to step in here and figure this one out for me.

Offline WeatherGoose

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Re: their quality standards
« Reply #1 on: February 20, 2010, 12:46:03 PM »
I wouldn't loose any sleep over the CWOP QC stuff.  I have the same problem with my Dewpoint from time to time.  Their system is very limited in dealing with the microclimate aspect of a PWS and I figure that this is why these bogus warnings and other stuff keep happening. 

As an example... The NWS owned VP2 down in Oakhurst Ca. has one of the worst CWOP QC pages of any PWS around here.  I know the location for that station and it gets a lot of cold air settling at night which confuses the QC calculations something fierce.  I figure, if the NWS is blowing all that off, then I can blow off my bogus dewpoint warnings once or twice a month.

For me, I prefer to check my station QC status using MesoWest/MADIS.  They use a totally different system and I never see any errors on there at the same time that CWOP is complaining.

My two cents.  :)


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Offline Aardvark

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Re: their quality standards
« Reply #2 on: February 20, 2010, 01:01:31 PM »
I did some tweaking and I am confident that my equipment is fine, considering each console is pretty close in agreement with the other.

I will look at that other site as well.

Offline tomcj2

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Re: their quality standards
« Reply #3 on: February 20, 2010, 01:14:25 PM »
I just looked at your daily with local airports added
http://weather.gladstonefamily.net/qchart/C0005?date=20100220&addnl=C6735&addnl=KDSM&addnl=KIKV&addnl=KAMW&Add+to+charts=Add+to+charts&.cgifields=addnl
.  You seem to be running 3 mb higher than anyone else.  Could it be that you are sending the wrong adjusted value to them ?( ASOS rather than sea level rather than Madis).  I do not know what adjusted value they need.
Try using VPLive to send your data, it works for me.
« Last Edit: February 20, 2010, 01:18:59 PM by tomcj2 »

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Offline W Thomas

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Re: their quality standards
« Reply #4 on: February 20, 2010, 02:12:59 PM »
I was having barometric pressure inaccuracies previously and that was my problem , I was sending the wrong corrected data format to CWOP. I started sending the "altimeter" correction to them and seems to have cleared that.  BUT I still have some problems with dewpoint calculations from time to time. So far I haven't had a red X but I have seen it vary widely.

One thing I have found is that you will go whacky trying to keep top marks on the QC checks :-P


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Offline WeatherGoose

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Re: their quality standards
« Reply #5 on: February 20, 2010, 02:17:33 PM »
I did some tweaking and I am confident that my equipment is fine, considering each console is pretty close in agreement with the other.

I will look at that other site as well.

Thanks to Tom's link to your CWOP page, I looked at the error you are getting too.  2.5 mil is a pretty big difference.   You definitely don't want to leave it at TWO THUMBS down. I assumed your error was far less than that.  I tend to shoot for a 0.02 mil error between my station and CWOP's QC.  I often see a 0.00 error depending on the day.

When you tweaked your station, did you offset the BARO by that 2.5 difference?  I would try doing that and see what the QC system says about your readings. When I first set up my station, I had to nudge my BARO a couple of ticks to dial it in to be in better agreement with the other stations and the CWOP QC checks.

BUT I still have some problems with dewpoint calculations from time to time. So far I haven't had a red X but I have seen it vary widely.

One thing I have found is that you will go whacky trying to keep top marks on the QC checks :-P

The Dewpoint QC check seems to be the most fickle on most PWS pages I have checked including mine as I said.   Very annoying to see that RESITE YOUR SENSOR crap when 6 hours earlier you had a green check and two thumbs up!  :roll:

It definitely pays to take some of the CWOP QC stuff with a grain of salt, provided that you are getting green checks and two thumbs up most of the time. :)

« Last Edit: February 20, 2010, 02:21:36 PM by WeatherGoose »


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Offline tomcj2

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Re: their quality standards
« Reply #6 on: February 20, 2010, 07:36:10 PM »
I just looked at your current ( Feb 20) charts.

http://weather.gladstonefamily.net/qchart/C0005?date=20100221&addnl=C6735&addnl=KDSM&addnl=KIKV&addnl=KAMW&Add+to+charts=Add+to+charts&.cgifields=addnl

It looks like you have overcompensated.  I took about a week of tweaking the station before I was happy.  I also found that using WeatherLink to make the adjustments allowed me to fine, fine tune.

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Offline Aardvark

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Re: their quality standards
« Reply #7 on: February 20, 2010, 07:41:28 PM »
all I did was reset the elevation to what CWOP claims it should be, rechecked the coordinates, and that is all.   I also turned off the update from Weatherlink IP going to CWOP and relying on the one with WeatherDisplay, using their altimeter option to send it in metric.   

Then I spent all afternoon writing up an IEP.

Offline tomcj2

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Re: their quality standards
« Reply #8 on: February 20, 2010, 07:56:46 PM »
What was the difference in elevation before and after your changes.  Perhaps you should only use 60% of the difference.  How did you arrive at your initial elevation? 

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Offline Aardvark

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Re: their quality standards
« Reply #9 on: February 20, 2010, 08:00:43 PM »
my initial elevation was off the topographic map. Then I refined it last summer using a gps and it was still fine.  Then about  in December  the values starting showing error and getting that the pressure sensor was off.  So I checked settings on the Weatherlink IP console , the envoy in the basement and the other console that hangs in the kitchen.  All three were in agreement. So my thought was that either the calculations were off on the CWOP end, or the stations that they were comparing the data to were off. 

Now if you look at KDSM , that is the weather bureau - NOAA, they (CWOP) claim that their settings are off and need to be redone. That sort of supports my theory, that my data is good and their analysis is off.

Then I did comparison with other stations around where I am  and those values are within the same range as mine fits in, so go figure... I still think I am fine . ](*,)

Offline tomcj2

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Re: their quality standards
« Reply #10 on: February 20, 2010, 08:12:28 PM »
I would trust airports more than PWS's

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Offline Aardvark

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Re: their quality standards
« Reply #11 on: February 20, 2010, 08:17:29 PM »
probably, but considering the local airport..  I am going with the NOAA  station in Johnston, it is 1.5 miles away, and they agree with me.    Anyway,  I am pooped, been doing paperwork all day and I didn't eat lunch, so I am heading to that and a break... I will do some more probing..  I think the pressure is right, but I will have to do some downloading of data and do some old fashioned detective work...

Offline DJMWX86

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Re: their quality standards
« Reply #12 on: February 20, 2010, 11:22:31 PM »
They say that about my pressure as well but no ones complaining yet.  ;)
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Offline saratogaWX

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Re: their quality standards
« Reply #13 on: February 20, 2010, 11:26:33 PM »
I'd had a small issue with Baro until I discovered that an offset had crept into the WD settings

Check WD, Control Panel, Offsets and Initial Rain, Temp/Baro Offsets/Rain Totals TAB
Enter Barometer Offset 0.00 in, and press Set and Ok

Maybe that will cure it :)

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Offline W3DRM

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Re: their quality standards
« Reply #14 on: February 21, 2010, 12:32:00 AM »
Looking at your CWOP information page, it appears you have made a major correction of about -3.5mb to your readings. But, if you look at the data around 1700-2100 on 2/20 there is an incredible amount of fluctuation to your reported data. That can't be real. Were you doing something with your station during that period of time between 1700 and 2100 on the 20th?

If you have made some changes then I would suggest you leave it alone for at least 24hrs before making any further adjustments. It takes a while for the data to settle down and for the CWOP analysis packages to re-evaluate your inputs.

Also, be aware that the listed Neighboring Stations are NOT necessarily the same ones that CWOP uses for quality checking of your data. CWOP will not tell you what sites they are using to compare your data. Those Neighboring Stations are only shown to give you a sampling of what other nearby sites are reporting, and you have no way of knowing if they are accurate or not.

When I first started reporting data I had horrible CWOP quality data. Part of it was because I am at 4800 feet in elevation. Part of the equation giving me problems was that CWOP was using data from stations in Lake Tahoe which are at or above 6300 feet. Once I got that squared away by communicating with CWOP, and installing VPLive (from SoftWX) my issues literally disappeared and I rarely find anything but two green thumbs-up in my quality reports.

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Offline Aardvark

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Re: their quality standards
« Reply #15 on: February 21, 2010, 10:01:32 AM »
thinking about it a little more,  the other stations, the one's the Gladstones compare with are at different conditions and that there should be pressure differences over different terrain.  The Airport is in the Raccoon river basin and the NOAA is near the Saylorville lake area...   However, isn't the idea to measure atmospheric changes over a wide area rather than have one standard pressure, regardless of other conditions.  That would be like whining that the airport got 2 inches of rain and I didn't get any, therefore I am wrong ?

I am going with my settings and considering three other stations in my house, independent of each other are reporting about the same , I am going to figure that the pressure sensor is fine and let it go from there.  If CWOP isn't happy, well that is the data I am sending.

Offline tomcj2

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Re: their quality standards
« Reply #16 on: February 21, 2010, 10:19:03 AM »
t However, isn't the idea to measure atmospheric changes over a wide area rather than have one standard pressure, regardless of other conditions.  

During a period of little change all stations within a small radius should read the same because they are all reporting " Sea Level Pressure"  Wikipedia explains it as :

Mean sea level pressure


Mean sea level pressure (MSLP) is the pressure at sea level or (when measured at a given elevation on land) the station pressure reduced to sea level assuming an isothermal layer at the station temperature.

This is the pressure normally given in weather reports on radio, television, and newspapers or on the Internet. When barometers in the home are set to match the local weather reports, they measure pressure reduced to sea level, not the actual local atmospheric pressure. See Altimeter (barometer vs. absolute).

The reduction to sea level means that the normal range of fluctuations in pressure is the same for everyone. The pressures which are considered high pressure or low pressure do not depend on geographical location. This makes isobars on a weather map meaningful and useful tools.



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Offline Aardvark

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Re: their quality standards
« Reply #17 on: February 21, 2010, 04:33:06 PM »
graph is beginning to look better, lines closer between what is and analysis.. I am going to wait a few days for the data to settle out.

I think I figured out the problem.. we disagree on elevation.  So I set my elevation to what CWOP claims it is rather than what it is.

Ah..  which brings out a question.  Now the elevation, assuming that the ground is not moving up or down should be constant, but if the barometer is in the house and the item is above the ground level lets say 10 feet then shouldn't the elevation be compensated as well up 10 feet higher.  same if it is in the basement down 8 feet  then decrease 8 feet???  I am up 10 feet..

a thought worth losing sleep over.. definitely

Offline tomcj2

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Re: their quality standards
« Reply #18 on: February 21, 2010, 05:17:43 PM »
Yes.  The elevation should be the elevation of the barometer, the console in your case.

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Offline DanS

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Re: their quality standards
« Reply #19 on: February 21, 2010, 06:12:48 PM »
I also noticed that upon signing up with CWOP they entered my elevation differently than what I submitted. I sent in a correction and eventually got it straightened out. Since they compare me with the airport nearby I entered my elevation the same as the airport's. (1/2 mile difference between us).
« Last Edit: February 21, 2010, 06:49:35 PM by DanS »

 

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