RainDayThreshold

[mcrossley]

Steve

I understood (and put in the Wiki) the following...

RainDayThreshold=-1 The threshold value which the daily rainfall has to exceed for the day to be considered a 'rain day'. Default -1 = 0.2mm or 0.01in. Value is entered in your current rain units.

But it appears that the threshold used is >= the value in the ini file (or the default in my case), rather than simply greater than?

EDIT: Or I wonder is it because my 0.2mm of rain is > 0.2 due to rounding/floating point errors?

EDIT2: Um, no rounding/calibration error I can see. Cumulus recorded my rainfall on the 28th as 0.199791878461838mm, but also counted that as a rain day.

[steve]

Cumulus recorded my rainfall on the 28th as 0.199791878461838mm

It writes the rainfall to the log files to 1 decimal place (for millimetres) so I assume it actually wrote 0.2 to the log file? Values like the one you've quoted appear in today.ini simply because I don't bother doing any rounding on them and that's how floating point values come out when you do that.

The check that it does is >= and it rounds to 3 decimal places to do the check. So the value you've quoted rounds to 0.2 and is a rain day by default.

[mcrossley]

Thanks Steve I'll amend the wiki...

[Toongsteno]

ok, -1 corresponds to 0.2 mm, but if i want to modify? 0 is more or less? and how much more or less? Where can i find these informations?
Thank you

[steve]

I don't really understand the question. Any positive value is just the value you specify, in the rainfall units that you are using in Cumulus. Zero would mean that every day was counted as a rain day, so you probably don't want that.

[freddie]

I don't really understand the question.

I think Toongsteno doesn't realise that you just put in your threshold value - and that "-1" is a placeholder that says "use the default that's in the code".

[steve]

Ah, OK - as if "-1" was a code for 0.2 mm, so what are the codes for other values...

Hopefully now clear

[freddie]

Ah, OK - as if "-1" was a code for 0.2 mm, so what are the codes for other values...

Yep, that's what I was driving at...

[Toongsteno]

Exactly. Sometimes Cumulus (via my WS) reports that there were some precipitations but it is not true. In fact there were some night frost or dew, but the setted threshold makes read this as rain. I'm trying to figure out which is the best setting to ignore that light amount of water. I've not been able to understand how to modify the Cumulus .ini, and the only reference i've found is this post. Where is it explained what the several values stand for? Anyway, thank you Steve and Freddie, i understood a little more

[steve]

There aren't any settings to make Cumulus ignore rainfall completely. The RainDayThreshold setting only affects the count of the number of days where rain is regarded as having fallen, for example on the "This year" and "This month" screens etc.

Your rain gauge has a resolution of 0.3mm - that's how much rain is in one tip. So if you set RainDayThreshold=0.4 Cumulus will only count days where at least two tips occurred as a 'rain day'. Note that if your locale uses commas for decimals, you also need to use commas in cumulus.ini, so you would put RainDayThreshold=0,4

You should edit cumulus.ini with Cumulus stopped.