I’m trying to calibrate my new UVN800 by comparing my UV data with a government website set in Sydney, 80 kilometres north east of here. I am doing this by going into Control Panel > Offsets and Initial Rain > VP UV/ET > Davis VP UV Offset (% Adjust). While I don’t have a Davis UV meter, adjusting things here seems to work anyway. You can see the situation for today (very sunny and bl**dy hot) in the first attachment and the government data in the second. I adjusted it all from +15% to +12% around midday today.
You have to look carefully at Attachment 1 to see the effect. Before midday, solar and UV were about the same on the graph; after midday, UV is below the solar level. My settings are in Attachment 3 if that helps.
I have two questions: First, should solar and UV be the same and I should put it back to +15%? Second, am I calibrating it following reasonable procedures.
Cheers,
Rick
PS. Incidentally and for Australian readers, I purchased my UV Meter online from the US and had it delivered to my daughter’s address there. All up, including US taxes and her charges to forward it to me here in Australia, it cost me less than $75 (purchase price was $49.50 and they’ve had it on sale for $35 since then). Had I bought it here in Oz, it would have cost me $129 from Australian Geographic – the OS official outlet here. And I would have had to drive 60 kilometres to get it or paid a further $15 postage. Jerry Harvey can’t argue against my action here about buying things online, eh?
Solar and UV aren’t the same thing. Solar measures the amount of solar energy radiation
and the UV sensor measures the UV spectrum of the sunlight…apples and oranges…
The both type of radiation have its maximum at noon (on a clear day) so the graphs looks similar.
You cant calibrate the UVN800 sensor you can only tweak it so it will work better.
look here. How to tweak a UVN800
WD calculate the solar energy based on the values you get from the UNV800 sensor. These calculations
are very raw ex 1 UVI is 100 W/m2 and that is not a correct value.
Thank you very much for your response to my message. It is most appreciated. I do apologise that it has taken me so long to get back to you. No excuse – just slackness on my part.
I do have some questions/comments on what you said, please:
I am aware of that, but note that I can tweak them so they are the same. Hence my earlier question.
Yes, I knew that too. However, I am wondering if what I was doing by calibrating it as suggested in the post above is kosher. It seems to work fine to me, but maybe I’m missing something critical here. It is labelled “Davis UV . . .” Have you tried calibrating it using that option rather than bending it toward the sun?
Yes, I’m aware of that too and, if I can purchase the necessary parts at a local electronics store, will build one. I’m away at a conference for the next week, but intend following it up when I return. If it all works out OK, I’ll let you know at the time.
