Bright Sunshine Totals

[Paul C]

Steve

Can you confirm, what the column number would be for the daily sunshine total.

(have import the txt file into a spreadsheet going back to 2007)

thanks

[steve]

Sunshine hours are in the 25th column.

[Paul C]

Thanks

First day of trial

Cumulus 6.1hrs ( 80%/0.83)
WLR 3.3hrs
Approved Meto Sunshine Recorder- 2.2hrs

So - what would you recommend to change on Cumulus to "lower" the figure ?

[steve]

In the unfinished experimenting that I did I found I had to set the transmission factor quite high to get the actual readings to stay below the theoretical max, these were the figures I'd got to:

SunThreshold=75
RStransfactor=0.93

Those seemed to be giving me reasonable results, but I didn't really spend a lot of time on it. What I was doing was comparing the actual readings with the current max (hover over the figure to get the max), and watching the 'sun' icon to see if it matched when the sun was actually out or not. It's made more difficult by the fact that the Davis only updates once a minute.

You can also now use the 'Sun Minimum' setting in the latest build to cut off the periods at the start and end of day where the solar reading is too low to make a proper judgement. You should be able to get an idea of a suitable figure from the graph.

[Paul C]

I have been looking at the "sun min" setting but I dont understand it, sorry. Are you suggesting that I enter say 120wm2 so it ignores everything below that figure when calculating bright sunshine figure, this then would be similar to WLR ?

My test is still ongoing but the last three days have produced zero sunshine which doesnt help. Of the days this month when sun has been recorded Cumulus is still lower than my Met Equipment. Latest settings I have is Sun Threshold 75% and Trans Factor 0.93 - what would you suggest to make it increase its figure ?

(Sun Min is still on zero for the moment)

thanks

[steve]

I have been looking at the "sun min" setting but I dont understand it, sorry. Are you suggesting that I enter say 120wm2 so it ignores everything below that figure when calculating bright sunshine figure, this then would be similar to WLR ?

That's what the "sun min" setting does, yes; but 120 seems much too high to me.

My test is still ongoing but the last three days have produced zero sunshine which doesnt help. Of the days this month when sun has been recorded Cumulus is still lower than my Met Equipment. Latest settings I have is Sun Threshold 75% and Trans Factor 0.93 - what would you suggest to make it increase its figure ?

Reducing the threshold would increase the total hours, as would reducing the transmission factor.

I can't really offer any concrete advice about numbers, because I haven't had chance to do any proper testing myself yet.

[Paul C]

Thanks Steve - now set it 100wm2 and reduced the other thresholds

Has anybody been testing against an old sunshine recorder ?

[steve]

Has anybody been testing against an old sunshine recorder ?

Not that I'm aware of.

[Paul C]

test results so far this month
WLR - refers to Weatherlink Reporter Software, which is completley seperate to Weatherlink
Recorder - my old Casella Mk2 Sunshine Recorder - recording onto cardboard (standard Met Equipment)
No conclusion as yet !

[Paul C]

Month end data now attached - Cumulus is now on the low side - WLR similar to sunshine recorder. Cloudy days handled well by both.

[Paul C]

I have now completed my second month of trial - Cumulus now similar to to my old sunshine recorder. WLR starting to produce higher figures. One thing of note is that Cumulus operates 0900-0900hrs so on some days the sunshine say between 0700-0900hrs is recorded against the wrong day, just wondered if this could be changed ?

So best results so far are for
Sun Threhold 68%, Sun Min 100 wm2, Trans Factor 0.88

Will see how tyhis month goes withy increased strength of the sun.

[steve]

One thing of note is that Cumulus operates 0900-0900hrs so on some days the sunshine say between 0700-0900hrs is recorded against the wrong day, just wondered if this could be changed ?

It's not straightforward, because it needs to go into a log entry at 0900, so I'd need to store the value somewhere (today.ini or something) until it was needed. But I'll look into it.

[Paul C]

One thing of note is that Cumulus operates 0900-0900hrs so on some days the sunshine say between 0700-0900hrs is recorded against the wrong day, just wondered if this could be changed ?

It's not straightforward, because it needs to go into a log entry at 0900, so I'd need to store the value somewhere (today.ini or something) until it was needed. But I'll look into it.

Steve

Did you manage to have ago at the above ? - I cant remember ?

Anyway Cumulus now more and more in line with Sunshine Recorder

Sunshine Recorder 200.2hrs
Cumulus 190.3

I am happy with that, especially as the art to reading the sun recorded on cardboard isnt easy and open to errors (IMHO)

cheers

[steve]

Did you manage to have ago at the above ? - I cant remember ?

I did it today, as it happens (so it will be in the next release). I've started experimenting with my settings, now I have another sun recorder to play with. Completely unbroken sunshine today, from sunrise to sunset.

[scramblers]

Hi Paul,

I have just installed a VP2+ and I am trying to set up the "sun shining" bit. I have now used your calibration figures of 68%, 100 W/m^2 and 0.88. Do they still hold true? Or have you modified them?