[wxqc] Temperature "errors"

[Gary J. Ferdinand]

Evan, I'm the guy who tried to help with the topo suggestion.  Please get
your target correct.

Gary

> -----Original Message-----
> From: wxqc-bounces at lists.gladstonefamily.net
> [mailto:wxqc-bounces at lists.gladstonefamily.net]On Behalf Of Evan
> Bookbinder
> Sent: Thursday, September 22, 2005 7:43 AM
> To: Discussion of weather data quality issues
> Subject: Re: [wxqc] Temperature "errors"
>
>
> Gary,
>
> I guess a little sarcasm is good now and again, but I found that your
> tongue-in-cheek comments were a bit out of line. Several members of this
> group have provided excellent documentation on what QC is, how it's done
> and what it means. These insightful documents likely would have
> circumvented the need for your email.
>
> Ignoring some incorrect assumptions made on the development of frost and
> the killing of tender vegetation, let's make the obvious assumption that
> your observation of 32F is correct.
>
> 1.) Minimum temperatures are HIGHLY susceptible to terrain and land
> cover/usage. It is perfectly normal to have a 10 or more degree spread
> over several miles and a hundred feet elevation change on a clear, calm
> night. (I'm not going to get into a dissertation on cold air drainage
> and nocturnal inversions here).
>
> 2.) Not NOAA, nor anyone else, is rejecting anyone's data, contrary to
> your belief. We receive all data, good and bad. The QC tool merely
> provides you with the feedback necessary to determine whether an
> instrument could be failing or is incorrectly sited. These reports
> should never be used on a daily basis (due to local effects, frontal
> passages, etc...) and a long term average on the order of a few weeks
> should be used to determine systematic errors with your instrumentation.
> In this case, it's obvious that your local siting plays a huge roll in
> cold air drainage at night. The algorithm is nothing more than a
> mathematical equation used to relate your readings to surrounding sites.
> There's no standard "negative lapse rate" for cold air draining, so
> there's nothing that can be done to factor elevation into the
> algorithm.  So, if your daytime highs are QCing just fine, feel free to
> ignore the QC message on the min temperature.
>
> Hope this helps,
> Evan
>
>
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