Topic: UV values ​​fluctuate

[mandersp]

The Froggit DP300 has a uv and solar.
Now the UV value fluctuates all the time.
How can I make the UV values ​​more stable?
I have already calibrated the UV gain to 0.7.

https://weerstationafferden.nl/pws-froggit/index.php
https://www.wunderground.com/dashboard/pws/IAFFER10

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Kind regards
Piet Manders
Weather station Afferden

[Rover1822]

Your post is going to open up a lot of questions, things like:

1. where is your station in relation to the sun
2. What are your shading conditions
3. What was your cloud cover , and do you get that even a blue sky may not be cloud free

So answer those first

[broadstairs]

In addition to those questions do you realise your UV sensor is not a real one but it is calculated from the solar readings.

Stuart

[Gyvate]

without any corrections/adjustments (gain factor = 1.0) the UVI is calculated by the firmware as 10% of the solar readings and rounded to an integer number.
The WS68 (Froggit DP300) transmits readings every 16 seconds. When the solar radiation (the light intensity) measured fluctuates, usually due to clouds, automatically the UVI also fluctuates.
Factually in this time window also the UVI changes in reality as there is less solar exposure.
The smoothing of the UVI value graphs, which for whatever reason you want to have, does not reflect reality - maybe a beauty concept ...
Think about it ...

[sailingby]

I’ve adjusted the gain on mine to get realistic levels for the uk.

Unadjusted I would be getting a great suntan in April 

[Gyvate]

I’ve adjusted the gain on mine to get realistic levels for the uk.

Unadjusted I would be getting a great suntan in April 

that's fine - we recommend using a gain factor between 0.65 and 0.75. The individual local best fit is to be determined at a (visible) cloud free day in summer by comparing your readings with an as close-by as possible official metereological station with real UV sensors and fine tune your gain factor that way.

However, that will not smoothen the UVI graph 

[sailingby]

That’s the gain factor range I've used, tweaked a to match up on a clear day to Apple weather.

[Vasco]

I have already calibrated the UV gain to 0.7

To make mine read anything like real values I use 0.6, and that doesn't work all the time.

In addition to all the above, please note that the solar/UV sensor is very susceptible to solar amplification from "fair weather" clouds, so readings are often higher than the theoretical maximum for lat/long/date. . .

[sailingby]

Ecowitt were asking for feedback a while back, re development of an independent uv sensor. Is there any news on this?

[Gyvate]

I have already calibrated the UV gain to 0.7

To make mine read anything like real values I use 0.6, and that doesn't work all the time.

In addition to all the above, please note that the solar/UV sensor is very susceptible to solar amplification from "fair weather" clouds, so readings are often higher than the theoretical maximum for lat/long/date. . .

that latitude dependent solar max value is rather theoretical (see also our WiKi) - events like e.g. the often occurring cloud-edge-effect are not considered.
The high readings are real and seriously considered in the photovoltaic area - but they may not look as beautiful as the theoretical solar max bell curve 

[Gyvate]

Ecowitt were asking for feedback a while back, re development of an independent uv sensor. Is there any news on this?

as far as I know this is still under consideration - it's also a business case - how many will buy such a special device which will not be cheap, will others be willing to pay a higher price if this were integrated into new editions of existing sensor arrays, etc. compared to the R&D costs ...

[Vasco]

The high readings are real

Agreed.

But it's interesting (to me) that WU (WD upload, not gateway) doesn't seem to show the highest values recorded by Ecowitt. . . which is probably because I only upload every 5 minutes for both of them.

[mandersp]

Thanks for all the information.

I know enough, thanks for that.

Kind regards
Piet Manders
Weather station Afferden