[wxqc] Comparing stations

Paul Grace paulgrace at lookoutranch.com
Sun Oct 30 11:15:17 CDT 2011


"MADIS does NOT throw out any data at all."  Ah.  I interpreted "Your
readings are not within an acceptable error range" as the data was not
acceptable.  The temp analysis is often wrong for my location by 20F, and
the dew point analysis is similarly horked.  It's humorous-

  _____  

From: wxqc-bounces at lists.gladstonefamily.net
[mailto:wxqc-bounces at lists.gladstonefamily.net] On Behalf Of Ted Lum
Sent: Saturday, October 29, 2011 21:27
To: Discussion of weather data quality issues
Subject: Re: [wxqc] Comparing stations


Not flawed in that sense. It checks for stuck sensors. It checks for bounds;
temperature must be between -60 and +130 for example. It checks for Temporal
Consistency; temperature can't vary by more than 35 F/hour for example. It
does an Internal Consistency check; Dew Point Temperature can't exceed Air
Temperature for example. And it does the Spatial Consistency check but we
don't know what station(s) it uses when.

Most of all MADIS does NOT throw out any data at all. Worst it ever does is
flag it with the checks it failed.

On 10/29/2011 10:25 PM, Paul Grace wrote: 

Right.  I think it's not very good at determining what is "flawed" when
looking at data that has no close neighbors.  It exhibits a tendency to
throw out the very data that it most needs to fill in its holes.



From: wxqc-bounces at lists.gladstonefamily.net
[mailto:wxqc-bounces at lists.gladstonefamily.net] On Behalf Of Ted Lum
Sent: Saturday, October 29, 2011 19:13
To: Discussion of weather data quality issues
Subject: Re: [wxqc] Comparing stations



Well, we don't really know what MADIS includes so we can't say if it does
that or not, but it does take out flawed readings. Someone at NOAA ESRL/GSD
might be able to say how the algorithm works; I've never seen it as anything
but a black box.

On 10/29/2011 7:34 PM, Paul Grace wrote: 

I would guess that data should be accepted into the model, *unless* it has a
nearby data (hundreds of feet, not hundreds of miles) with which it does not
agree, or exhibits flaws such as stuck, zero, over limit, sensors, etc.



From: wxqc-bounces at lists.gladstonefamily.net
[mailto:wxqc-bounces at lists.gladstonefamily.net] On Behalf Of Ted Lum
Sent: Saturday, October 29, 2011 15:32
To: Discussion of weather data quality issues
Subject: Re: [wxqc] Comparing stations



AFAIK Philip takes the nearest 10 or so. MADIS has its own way of doing
things. I'd put it back on you and ask what would you like it to do? Nothing
can really invent stations and data where there isn't any, nor can it
manufacture a particular type of data. So there is no other data near you,
and no other data that has the same profile as you. What exactly is it that
you want?

On 10/29/2011 4:33 PM, John M. Markle wrote: 

  Not sure what going on here and as always when I ask something on wxforums
I get ingored so I really  don't expect an answer here either.
 Why are station that are 150 miles to 500 miles from me listed on my summa
ry page for comparsion. This is totally useless to me and I ame sure it is
also would be useless to anyone else also. Another thing I notice some of
these 
stations are under Continetal influces where I am under maritime influences.
Seem to be one would want to be compared to station in one own enviroment.
On this list the first station  listed is 150 miles from me and the last one
is 504 miles. Just 140 miles shy of Seattle, Washington.  Other thing I
notice is that they are all PWS stations. Too me this is the poorest choice
to use for comparison as most PWS owner  just throw their station up and
walk away. As long as it seems to be close it is good enough for them.
 
 Here is the link.  http://weather.gladstonefamily.net/site/D1453
 
 
 Like I said I don't expect an answer but thought I try any ways.
 
John 
KL7IFP 






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