On Thu, 25 Feb 2016 13:21:12 -0000, "JohnD" wrote:

"Desperate Dan" wrote in message
...

The only way to understand a site is to survey the site.

Sorry, but I don't really agree, or at least not completely. There's no
argument but that the gold standard is for a professional survey of each and
every site contributing data (to WOW in this particular instance). But
that's not practicable nor is it every likely to happen - although I
wouldn't exclude some more informed type of self-reporting/certification
than exists at present, maybe even encourage well-briefed amateurs in the
area to visit and comment.

However, that doesn't mean that all data from sites that haven't been
individually surveyed is equally bad and unreliable. Modern statistical
methods are quite powerful in monitoring the deviation of actuals from
gridded data calculated from the overall observational data set and should
quickly be able to prioritise site that offer consistently accurate data,
especially if the self-certification for exposure can be factored in too.
No-one is making the argument that this is ever going to be as good as data
from a well-exposed and professionally surveyed site, but I do strongly
suspect that this approach may well be more powerful than you might imagine.
Again I'd suggest looking at what CWOP does for the US.

JGD

Perhaps I am missing something here but if the modelling is good enough to
determine which actuals are 'good' and which are 'bad' then surely the modelling
doesn't need these actuals at all.

--
Norman Lynagh
Tideswell, Derbyshire
303m a.s.l.
http://peakdistrictweather.org

Sorry, but I don't really agree, or at least not completely. There's no
argument but that the gold standard is for a professional survey of each and
every site contributing data (to WOW in this particular instance).

I understand where you're coming from here and respect your view but, should the gold standard in observations not be what we're striving for? Anything else is only "advisory".

"Norman Lynagh" wrote in message
...
On Thu, 25 Feb 2016 13:21:12 -0000, "JohnD" wrote:

"Desperate Dan" wrote in message
...

The only way to understand a site is to survey the site.

Sorry, but I don't really agree, or at least not completely. There's no
argument but that the gold standard is for a professional survey of each
and
every site contributing data (to WOW in this particular instance). But
that's not practicable nor is it every likely to happen - although I
wouldn't exclude some more informed type of self-reporting/certification
than exists at present, maybe even encourage well-briefed amateurs in the
area to visit and comment.

However, that doesn't mean that all data from sites that haven't been
individually surveyed is equally bad and unreliable. Modern statistical
methods are quite powerful in monitoring the deviation of actuals from
gridded data calculated from the overall observational data set and should
quickly be able to prioritise site that offer consistently accurate data,
especially if the self-certification for exposure can be factored in too.
No-one is making the argument that this is ever going to be as good as
data
from a well-exposed and professionally surveyed site, but I do strongly
suspect that this approach may well be more powerful than you might
imagine.
Again I'd suggest looking at what CWOP does for the US.

JGD

Perhaps I am missing something here but if the modelling is good enough to
determine which actuals are 'good' and which are 'bad' then surely the
modelling
doesn't need these actuals at all.


Data assimilation is about nudging the model to a solution that better fits
the observational data. It does need actuals to fine tune its analysis.
After all forecasting short term is basically an initial value problem, and
so if data assimilation is done every 3 or 6 hours then nudging is required.
When continuous assimilation comes onboard every piece of data will be vital
since the short time-scales will require a greater accuracy on spatial
scales to avoid numerical instability in the assimilation process.

Will
--
" Some sects believe that the world was created 5000 years ago. Another sect
believes that it was created in 1910 "
http://www.lyneside.demon.co.uk/Hayt...antage_Pro.htm
Will Hand (Haytor, Devon, 1017 feet asl)
---------------------------------------------

"Desperate Dan" wrote in message
...

I understand where you're coming from here and respect your view but, should
the gold standard in observations not be what we're striving for? Anything
else is only "advisory".
===================================

Isn't that the counsel of perfection though? Yes if it were possible then
every site contributing data should be professionally inspected and rated.
But there's presumably no resource to do that.

In the meantime, there's a substantial body of real-time WOW data that can
potentially add value and a refinement in local accuracy to near-term
forecasts. Should that value just be ignored and the readings thrown away?
Surely it makes sense to extract as much usefulness as possible from that
WOW data as possible, even given that the individual sites may not be of
gold standard accuracy and exposure.

On Thursday, 25 February 2016 13:49:56 UTC, wrote:

Data assimilation is about nudging the model to a solution that better fits
the observational data. It does need actuals to fine tune its analysis.
After all forecasting short term is basically an initial value problem, and
so if data assimilation is done every 3 or 6 hours then nudging is required.
When continuous assimilation comes onboard every piece of data will be vital
since the short time-scales will require a greater accuracy on spatial
scales to avoid numerical instability in the assimilation process.

There must be myriad examples where actuals are vital for the short-range - the thundery low coming up from the south where rainfall totals and location of storms is difficult or knife-edge rain/snow situations where half a degree of lowering in heavy rain turns it to snow etc.

Richard

Data assimilation is about nudging the model to a solution that better fits
the observational data.

Even if that data is inaccurate?

"Desperate Dan" wrote in message
...

Even if that data is inaccurate?

Look, I don't work for UKMO and have no direct knowledge of the plans for
WOW, but I'm guessing that the right statistical approach over time within
WOW will readily identify which WOW contributors _do_ generate more reliable
data and will weight those particular observations accordingly. Don't
underestimate the power of statistics in this context.

Look, I don't work for UKMO and have no direct knowledge of the plans for
WOW, but I'm guessing that the right statistical approach over time within
WOW will readily identify which WOW contributors _do_ generate more reliable
data and will weight those particular observations accordingly. Don't
underestimate the power of statistics in this context.

Within the Met Office, and worldwide through the WMO, instrumentation is standardised. This doesn't mean that all instruments are the same, but that all instruments achieve the same measurement standard as defined by WMO No8. The reason for this is fairly obvious. WOW, as far as I am aware, has no standards whatsoever so all, and I really mean all, data coming from WOW is suspect. That it should be used in an advisory capacity is an excellent idea. That it should be used to enhance model forecasts is, to my mind, folly in the extreme!

WOW, as far as I am aware, has no standards whatsoever so all, and I really mean all, data coming from WOW is suspect.

MetO climate sites, including Copley, report through WOW. The are subject to regular MetO site visits and instrument checks. They are also run by dedicated observers. Our data is hardly suspect and probably more accurate than many MetO AWS systems! We have very high standards.

Ken
Copley climate site
Teesdale

On Thu, 25 Feb 2016 06:58:21 -0800 (PST), Desperate Dan
wrote:

Look, I don't work for UKMO and have no direct knowledge of the plans for
WOW, but I'm guessing that the right statistical approach over time within
WOW will readily identify which WOW contributors _do_ generate more reliable
data and will weight those particular observations accordingly. Don't
underestimate the power of statistics in this context.

Within the Met Office, and worldwide through the WMO, instrumentation is standardised. This doesn't mean that all instruments are the same, but that all instruments achieve the same measurement standard as defined by WMO No8. The reason for this is fairly obvious. WOW, as far as I am aware, has no standards whatsoever so all, and I really mean all, data coming from WOW is suspect. That it should be used in an advisory capacity is an excellent idea. That it should be used to enhance model forecasts is, to my mind, folly in the extreme!

I'd go along with that.

--
Norman Lynagh
Tideswell, Derbyshire
303m a.s.l.
http://peakdistrictweather.org