Record hourly rain, but no rainfall all day

[KarlS]

Hi Steve:

Cumulus recorded a new "High Hourly Rain" of 153.4 mm at 4:27 this morning, however, all other rain indicators for today show no rain at all. We've had quite a lot of rain over the last two weeks, but it's been dry for the last 24 hours. I could reset it to the previous record of 18.3 mm, but this was "recorded" on December 20, 2011 and I always disconnect the rain gauge between November and March . Something appears to be wrong here ...

Any ideas?

[steve]

I'm not sure what it is you're asking for advice about.

If you want to know what to reset the record to, then I guess you'll have to find the last 'real' record, from before November?.

If you want to know where it came from in the first place, then I'm surprised that you're not aware that this is just one of the things that Fine Offset stations do, as I and others keep saying on a regular basis on the forum. Cumulus attempts to ignore large bogus increases in the rain total. And for the 'last hour' and 'rain rate' figures, it provides 'spike removal' settings - they're on the calibration screen.

[water01]

Check you haven't got a spider in there tipping the cup, it happened to me!!

[KarlS]

Steve:

I'm perfectly aware of the deficiencies of the Fine Offset stations. But like with everything else: if you want better quality you have to pay more … and my budget doesn't allow for a Davis.

Normally I run Cumulus 24/7, but today I stopped Cumulus to check if EasyWeather picked up this strange "record". It didn’t, so I concluded that the "Hourly Rain" is calculated by Cumulus and not reported by the weather station. Apparently this conclusion was wrong; I just couldn’t understand how no measured rain fall could compute to an hourly rain of 153.4 mm.

[steve]

Normally I run Cumulus 24/7, but today I stopped Cumulus to check if EasyWeather picked up this strange "record". It didn’t, so I concluded that the "Hourly Rain" is calculated by Cumulus and not reported by the weather station. Apparently this conclusion was wrong; I just couldn’t understand how no measured rain fall could compute to an hourly rain of 153.4 mm.

The hourly rain is calculated by Cumulus. All the station supplies is a 'counter' of the number of rain bucket tips which it thinks have occurred since it was last reset. Cumulus has to calculate everything from this figure. This figure has a tendency to suddenly increase. Sometimes it later goes down again, but normally once it's jumped up it stays there. Cumulus has mechanisms for attempting to ignore this strange behaviour as far as the daily total is concerned (it readjusts its record of what the total would have been at the start of day according to the new rules that the station has just invented). The 'last hour' and 'rain rate' figures also suffer when the counter does stupid things; this is why I have provided 'spike removal' settings for these items to put them under user control.

The diags logs show what happened to the rain counter, if you want to look in there. You can then look in the easyweather.dat file to see Easyweather's view of the rain counter (it's the 21st field in each entry). Cumulus represents the counter in mm, EW in 'tips'.

Note that you can't necessarily compare what Easyweather does retrospectively from the 'same' data; using the logger data is not the same thing as having to cope with reading the data live. Or perhaps Easyweather is much better software than Cumulus; I've just done the best I can.

[KarlS]

Hi Steve:

Thanks for the detailed explanation. When I checked the EasyWeather data, I only looked at the "rain in last hour" column, which stayed at 0 throughout. There are however strange data for the ticks counter and total rain at 03:28:23 (line 21 in the attached file).

I will set a spike removal value in the calibration dialog. Thanks again for a great program and support.

[stormchaser911]

Can some one give me the exact numbers for were in cumulus in calibration what we set the ofset to and also the multiplyer and also spike to? i want everything to be working properly as well. If some one could throw up numbers for all these would be very helpfull. Thanks

[steve]

Can some one give me the exact numbers for were in cumulus in calibration what we set the ofset to and also the multiplyer and also spike to? i want everything to be working properly as well. If some one could throw up numbers for all these would be very helpfull. Thanks

You don't need calibration settings unless you know that your station isn't giving correct results, in which case you would have some 'correct' readings from somewhere that you would use to work out the calibration settings. The one exception to this would be if you wanted to apply a compensation for the height of your anemometer: http://wiki.sandaysoft.com/a/Wind_measurement

And as it says in the help, the 'spike removal' settings only apply to Fine Offset and La Crosse stations (which are the ones which tend to give faulty readings).

[steve]

I've moved your post to a new topic in the Davis section.