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Question about rainfall rate calculation

Discussion specific to Oregon Scientific weather stations
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Question about rainfall rate calculation

Postby kinder » Wed Nov 10, 2010 12:11 pm

For people using older oregon scientific weather stations,there is a probem with the rainfall rate,according to the manual of the weather station.
The rainfall rate reported by the station clears to zero 2 hours after the rain has stopped.Thats ofcourse a hardware related problem,but i wonder if it is possible to do something to fix the display of the rate in software basis.
I thought that if for 1 hour the rainfall ammount remains the same,then there is no rainfall occured.If thats happen then the program could reset rainfall rate to zero,and keeps a record of the previous rate.If the rate has changed to something else than zero,new rainfall rate occured.
I don't know if that solution can be done easily,but for some oregon users maybe a nice feature if it is done ok.

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Re: Question about rainfall rate calculation

Postby steve » Wed Nov 10, 2010 12:27 pm

I never really saw that as an issue when I used my WMR928. The problem is that it's difficult to determine whether it's actually still raining or not with a TBR, particularly one that has a large 'tip' such as the WMR928 (etc), so I guess this is why they chose the 2 hour period. But I agree that 2 hours is perhaps too long a period for the rate to return to zero; on Davis stations the rate returns to zero when no tips have occurred in 15 minutes - but that does have a much smaller 'tip'.

For stations which don't supply a rain rate (such as Fine Offset stations) Cumulus calculates a rain rate; but the current calculation is quite simple and needs enhancing. I have an enhanced algorithm, based on the Davis one, and I did try using it once, but there are problems using it with long logger intervals, so I gave up on it temporarily. At some point I propose to try again to get it working, and if successful I'll offer it as an alternative to the station's calculation for other station types too, such as Oregon Scientific.
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