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Rain rate graph and constant rain with 1.9.4 beta 1082

Posted: Wed 14 Aug 2013 7:02 pm
by SamiS
Hello,

It has been raining quite constantly almost all day today. For some reason Cumulus draws rain rate graph as many consecutive rain spikes instead of constant low rain rate. Please see the pictures attached.

Is this a issue of my Fine Offset station or a bug or feature of Cumulus? Error log is clean so spike removal is not the issue here.

Re: Rain rate graph and constant rain with 1.9.4 beta 1082

Posted: Wed 14 Aug 2013 7:06 pm
by steve
Fine Offset stations don't supply a rain rate, so Cumulus calculates one. It uses a simple algorithm based on the amount of rain the station has recorded in the last five minutes. So, if no tips are recorded for more than five minutes, the rate returns to zero. Your rain rate has been just over the threshold of one tip every five minutes for most of the day.

Re: Rain rate graph and constant rain with 1.9.4 beta 1082

Posted: Wed 14 Aug 2013 7:56 pm
by SamiS
Ok, that explains it. Would it be difficult to implement a user configurable period for the average calculation? Or should it just count it for 10 minute period instead of 5 minutes? Or is it just me who thinks that this graph is almost not worth showing at all when it is like my example? :roll:

PS. Please do not get offended with the previous comment, I do really appreciate your work Steve.

Re: Rain rate graph and constant rain with 1.9.4 beta 1082

Posted: Wed 14 Aug 2013 8:22 pm
by steve
SamiS wrote:Ok, that explains it. Would it be difficult to implement a user configurable period for the average calculation? Or should it just count it for 10 minute period instead of 5 minutes?
5 minutes is an arbitrary period for doing the calculation, as there is no standard for the calculation of rain rate. 10 minutes is an equally arbitrary period. I could make it configurable, you could set it to 10 minutes, and the effect would be that the calculation would come out at approximately half the value all the time, and the graph may still not come out to your liking. And when your rain rate is one tip every 11 minutes you will have a graph that looks similar to the one you have now.
Or is it just me who thinks that this graph is almost not worth showing at all when it is like my example?
I'm not sure what your point is. Is the graph ever worth showing? You would like an option to blank out the graph when the rain rate happens to be just under a tip per 5 minutes? You could just not look at it ;)

Your station doesn't supply a rain rate. Cumulus provides a figure that gives you a rough idea of the rain rate. You don't find the figure useful, that's fair enough, you don't have to use it. I'm not offended.

The actual solution (apart from Fine Offset actually making an effort for a change and making their stations supply a rain rate figure), as I've said here many times before, is a better algorithm for calculating the rain rate that doesn't use a fixed period, similar to the way that Davis stations calculate the rain rate. The code is already in Cumulus, but there are problems with it under some circumstances (just after start up). One day I might find the time and summon up the enthusiasm to look at it again to see if I can make it work all the time.

Re: Rain rate graph and constant rain with 1.9.4 beta 1082

Posted: Wed 14 Aug 2013 8:44 pm
by SamiS
steve wrote:I'm not sure what your point is. Is the graph ever worth showing? You would like an option to blank out the graph when the rain rate happens to be just under a tip per 5 minutes? You could just not look at it ;)
My point was, that the graph looks like it is "broken or something" if you look at it as a "normal human" who does not understand a bit of what actually happens on the weather station or cumulus. It just does not "look like continuous rain". However the rain rate itself is a figure that interests at least some people.

I apologize that my non-native english sometimes may make it harder to "get it" what I'm trying to say. :?
steve wrote:The actual solution (apart from Fine Offset actually making an effort for a change and making their stations supply a rain rate figure), as I've said here many times before, is a better algorithm for calculating the rain rate that doesn't use a fixed period, similar to the way that Davis stations calculate the rain rate. The code is already in Cumulus, but there are problems with it under some circumstances (just after start up). One day I might find the time and summon up the enthusiasm to look at it again to see if I can make it work all the time.
I understand that software is only a partial solution to el cheapo hardware. :lol:

But anyway at least I keep my thumbs up for all your efforts to make cumulus even better.