When I looked at the ws28xx driver code I see the likes of data._Rain1H used in the rainRate calculation so that lends weight to the use of one hour rainfall data. If you are a glutton for punishment search the forums (weewx-user I think, but could be weewx-development) for calculation of rainRate - a few years ago we were revising the rainRate calculation in StdWXCalculate (or were we pulling the calculation out of some drivers, I cannot remember) and there was quite a thread on it. There are various methods of calculation each with their own pluses and minuses, eg reducing the ‘window’ used reduces the taper period, using a simple rain in the last hour based calculation can give a non-zero rainRate for up to one hour after the last rain fell.
Gary On Monday, 9 August 2021 at 03:22:17 UTC+10 [email protected] wrote: > Yes, the station in question is still the WS28xx, yes, there is a rainRate > = prefer_hardware setting in the config. Thanks, that explains it. > My best guess how the WS28xx driver calculates the rainRate is in some > kind "hour-based rolling average": the Super Cell event brought about 25mm > in one hour, a couple of weeks later another event brought ~38mm in one > hour: > > dateTime rain rainRate > 1626545100 4.12799999999879 37.173 > 1626544800 3.09599999999955 36.3272727272727 > 1626544500 7.48199999999997 32.737 > 1626544200 3.8700000000008 27.9744444444444 > 1626543900 2.83799999999974 25.2572727272727 > 1626543600 3.86999999999898 22.004 > 1626543300 3.8700000000008 17.978 > 1626543000 1.29000000000087 15.296 > 1626542700 1.54800000000068 13.953 > 1626542400 1.03199999999924 12.716 > 1626542100 3.09599999999955 10.96 > 1626541800 2.57999999999993 8.253 > > > gjr80 schrieb am Samstag, 7. August 2021 um 03:41:49 UTC+2: > >> I believe the answer will depend on your WeeWX configuration and the >> station/driver you use. A default WeeWX install is set to obtain rainRate >> from the driver but if the driver does not provide rainRate then WeeWX >> will calculate it (rainRate = prefer_hardware under [StdWXCalculate] >> [[Calculations]] in weewx.conf). I see in a previous thread you referred >> to 'your WS28xx' - if you are still using the WS28xx then the answer is >> likely in the WS28xx driver as the WS28xx driver is one of the few that >> does provide rainRate. I had a brief look at the WS28xx driver and it is >> not evident to me how it derives rainRate, but it is clear it does not >> use the same algorithm as WeeWX - that is also evident in the archive data >> you presented. >> >> If you wanted to use the WeeWX algorithm then you could change the rainRate >> = prefer_hardware to rainRate = software, I'm not saying the WS28xx is >> wrong, it just appears to use a different algorithm. On the face of it I >> don't really see anything wrong with your figures, though granted the 25.02 >> values are quite high given there was no rainfall for at least five minutes >> for the second 25.02 value, that could be because the WS28xx tapers the >> rainRate at a different rate to WeeWX. >> >> Gary >> On Saturday, 7 August 2021 at 05:47:40 UTC+10 [email protected] wrote: >> >>> Thanks Gary. Do you have an explanation for this: >>> >>> I got hit by a Super Cell thunderstorm some weeks ago which delivered >>> ~25mm in about 15 mins. Max rain rate for this month was those 25mm: >>> >>> archive_day_rainrate >>> dateTime min mintime max maxtime sum >>> count wsum sumtime >>> 1624312800 0.0 1624312803 25.28 1624395078 376.134682539682 >>> 288 112840.404761905 86400 >>> >>> select datetime, rain, rainrate from archive where datetime between >>> 1624384800 and 1624399200 ORDER by datetime DESC >>> dateTime rain rainRate >>> 1624393200 0.0 25.02 >>> 1624392900 0.0 25.02 >>> 1624392600 1.03199999999924 24.737 >>> 1624392300 6.19200000000092 21.512 >>> 1624392000 17.2860000000001 8.48545454545454 >>> 1624391700 0.515999999997803 0.076 >>> 1624391400 0.0 0.0 >>> >>> gjr80 schrieb am Mittwoch, 28. Juli 2021 um 14:30:52 UTC+2: >>> >>>> WeeWX calculates rainRate by summing the rain seen in the last 900 >>>> seconds (15 minutes) and scales this to a per hour figure by multiplying >>>> by >>>> 3600/900. So your 21.8 mm appearing in one packet/record would have >>>> resulted in 21.8. * 4 = 87.2mm/hr; exactly what you saw. Due to the 900 >>>> second window being used the 87.2 mm/hr value would have persisted for up >>>> to 15 minutes. The 34.9 value may have been the result of when the 21.8mm >>>> value arrived, impossible to say without seeing the exact loop >>>> packet/archive record history. You can change the 900 second window to >>>> some >>>> other value, say 600 seconds (10 minutes) and WeeWX would then take the >>>> rainfall seen in the last 10 minutes and scale that figure to a per hour >>>> figure (in that case multiply by 3600/600). >>>> >>>> This is covered in the [[RainRater]] >>>> <http://www.weewx.com/docs/usersguide.htm#%5B%5BRainRater%5D%5D>stanza >>>> in the User’s Guide. Note the Userks Guide states that 1800 seconds (30 >>>> minutes) is used by default for the window but the code actually uses 900 >>>> seconds. Must fix the documentation. >>>> >>>> Gary >>>> >>>> On Wednesday, 28 July 2021 at 22:10:21 UTC+10 wysiwyg wrote: >>>> >>>>> Hi ! >>>>> >>>>> I have a situation where I'm not sure about weewx behavior and how to >>>>> deal with it :-). >>>>> >>>>> I have made my own rain sensors: It reports rain every 2min30 and >>>>> reports 0mm when there's no rain. >>>>> Rainrate calculation is not done and not emitted by the sensor: Weewx >>>>> has to handle it. >>>>> >>>>> Now come a situation: My sensor crashed yesterday and did not reported >>>>> anything over the night (it was raining). >>>>> I rebooted it a few minutes ago, without power cycle, so I don't loose >>>>> the rain counter of the night => the sensor sent 21.8mm from the whole >>>>> night in one shot. >>>>> >>>>> I would expect that the rainrate shall not be calculated...or maybe >>>>> shall be calculate with a time span between last and previous sample >>>>> (yesterday before it crashed). >>>>> >>>>> it seems not working this way as weewx reported: >>>>> - 34.9mm/h at next report following the 21.8mm record. >>>>> - 87.2mm/h the following report 5min later. >>>>> >>>>> I assume maybe weewx consider "not rain data" = "0 mm of rain" ? >>>>> >>>>> I have a couple of questions: >>>>> - Is this behavior expected or maybe it's something that could be >>>>> improved ? >>>>> - Can I delete those rainrate sample from database ? >>>>> of course my daily rain graph is a bit weird, but I want to keep the >>>>> 21.8mm (so monthly or yearly records are ok), but I don't want to have my >>>>> yearly/alltime max rainrate using this wrong data. >>>>> >>>>> best regards, >>>>> >>>>> >>>>> >>>>> >>>>> >>>>> -- You received this message because you are subscribed to the Google Groups "weewx-user" group. 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