Hi
I like the many features that come with the Davis Vantage pro. Does anyone have the full kit? I am particularly interested in the extra temp and humidity sensors and the sunshine. I see weather display has the facility to record hours of sunshine. Would be good if this was illustrated graphically and in tenths of an hour. I would be interested to see any links to sites that are monitoring several temperature sensors and sunshine values graphically. 8)
I’ve had the 6161 “full kit” with solar, UV, and FARS for about 2 1/2 years now.
there is the sunshine hours screen, which has a column graph of the sunshine hours each day (and it shows the sunshine hours to deimal place)
Thank you
Could you please let me know whether the vantage pro logs sunshine amounts in hours in table form.
I can see that it logs hours and tenths on the home page :roll:
Regards
Rob
there is hours for each day under view, averages/extreme in WD, and on the web page averages/extreme
is that what you mean?
At Rob’s request…
The VP ISS/console logs only global solar irradiance, not sunshine hours. It’s what a software program can do with that solar intensity data that defines whether it’s capable of generating a value for bright sunshine hours (BSH). One problem of course is that by BSH meteorologists generally mean the value that would be recorded by a traditional Campbell-Stokes instrument. The reality is that C-S BSH is a rather arbitrary measure revolving around whether the sun is strong enough to burn a track in some standardised photographic emulsion, but AFAIK there’s no strict scientific definition of what constitutes ‘bright sunshine’, which creates a problem for the software writer. (It’s true that the WMO have suggested a figure of 120W/sqm as the threshold for BS but this actually relates to direct but than global irradiance - an important distinction - and is also rather arbitrary in that eg the threshold would be exceeded on some ‘cloudy bright’ summer days that wouldn’t register on C-S.)
So what people seem to want for serious use is a measure that provides continuity with historic records of BSH, ie as measured by C-S instruments. And arguably the only way for a software package to produce a credible figure for BSH is if the algorithm used has been validated against C-S data over the course of a year (ie under both winter and summer sun conditions). It would be interesting to know the method used in the WD calculation and whether the CS validation has been published. Certainly the Weatherlink algorithm which was available in v5.4 but taken out in v5.5 (but likely to be back in v5.6 or whatever) has (hitherto at least) relied on just on a threshold and so isn’t much good for serious use. Yes it produces a number but it’s only a rough estimate of true CS BSH and unlikely to be much good for detailed comparison with past data.
Of course once you start accumulating extended BSH data over several years with any constant AWS/software system at the same site & exposure you can get comparability with previous years to detect trends and so on. So whatever system you use has some value, but not really for direct comparison with historic data.
WD compares the raw wm/2 with is expected (for the time of day for your lat/long) and comes up with a solar %…and then you set a trigger point for that solar % which accumulates sunshine hours