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uk.sci.weather (UK Weather) (uk.sci.weather) For the discussion of daily weather events, chiefly affecting the UK and adjacent parts of Europe, both past and predicted. The discussion is open to all, but contributions on a practical scientific level are encouraged. |
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#81
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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 |
#82
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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". |
#83
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![]() "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) --------------------------------------------- |
#84
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"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. |
#85
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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 |
#86
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Data assimilation is about nudging the model to a solution that better fits
the observational data. Even if that data is inaccurate? |
#87
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"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. |
#88
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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! |
#89
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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 |
#90
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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 |
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