Maybe we didn't understand right.
Station show real value of UV index on my terminal at home.
But not on my web page by weewx. So it is settings in weewx

Dne sreda, 11. april 2018 15.08.09 UTC+2 je oseba Greg Troxel napisala:
>
> Damjan Hajsek <hajsek...@gmail.com <javascript:>> writes: 
>
> > Anyone know what to use in 
> > [StdCalibrate] 
> >     
> >     [[Corrections]] 
> > 
> > to correct UV index? Because now at night it is UV = 15 
>
> (I don't have any actual experience here, either with weewx calibration 
> or with UV sensors that ever show 15.) 
>
> Typically, "calibration" involves minor adjustments to a sensor that is 
> basically working ok, like adding 0.7 hPA to pressure.  There is an 
> underlying assumption that the sensor has the right slope but just a 
> small offset. 
>
> A UV sensor that reports a UV index of 15 at night sounds so seriously 
> off that it seems more likely that something is catastrophically wrong 
> which cannot reasonably be resolved with calibration.  I have not 
> checked calibration on my UV sensor, but it reliably shows 0 at night 
> and patterns that appear to corrrelate well with sunny vs not and sun 
> angle.  I would not be shocked if it reads 3.8 when it should read 4.0; 
> I would have to be far more thorough to figure that out, vs eyeballing 
> graphs and not being suspicious. 
>
> I would recommend looking at all other ways of observing the sensor 
> value (console?), and see if there are any setup errors. 
>
> Finally, I would log the data without calibration for a while, and graph 
> that in a scatter plot against UV data from some nearby station that you 
> believe is working ok.  If that turns out to be a line with slope 1 and 
> offset 15, then subtracting 15 is good strategy.  But until you know 
> that such a relationship holds, the assumption that there is a single 
> linear offset seems unwarranted. 
>
> Greg 
>

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