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Vantage Vue extreme high rain rate?

Posted: Sun 21 Oct 2012 12:36 am
by Paragon
Hello,
I noticed a while ago that the "(All time )High rain rate" showing on my web site and thus in alltimelog.txt has an odd number. The current value is 1440 mm/hr. Here are the last three values for it in alltimelog.txt:

Line 1429: 2011-04-26 11:40 886.200 "All time high rain rate" 2011-04-02 22:22 125.200
Line 1430: 2011-05-16 08:27 1280.000 "All time high rain rate" 2011-04-26 11:40 886.200
Line 54372: 2012-07-29 22:43 1440.000 "High rain rate" 2011-05-16 08:27 1280.000

The log lines for these times are these:
26/04/11,11:40:00,13.6,91,12.2,17.7,32.2,166,1,4.4,1007.18,886.2,23.4,56,8,12.1,13.6

16/05/11,08:25,14.1,83,11.2,30.6,56.3,263,0.0,5.8,1004.37,1096.0,18.2,59,38.6,11.9,14.1,0.0,0
16/05/11,08:30,14.1,84,11.4,30.6,66.0,261,3.8,6.6,1004.71,1096.8,18.2,59,40.2,11.9,14.1,0.0,0

29/07/12,22:40,11.8,92,10.5,29.0,51.5,53,52.8,22.4,1004.24,1302.8,17.6,59,16.1,9.0,11.8,0.0,0,0.00,0.00,6.4,0,0.0,81
29/07/12,22:45,11.7,93,10.6,30.6,51.5,53,6.0,23.6,1004.37,1304.0,17.6,59,19.3,8.8,11.7,0.0,0,0.00,0.00,6.0,0,0.0,63

As far as I can remember I wasn't fiddling with anything at these times. Indeed, on 29 July I was probably reading in bed at that time!

I am on v.1.9.2 build 1023.

Is there a known reason for this?

Thanks very much for your thoughts.

Graham

Re: Vantage Vue extreme high rain rate?

Posted: Sun 21 Oct 2012 2:43 am
by PaulMy
I believe the rain rate is in the dayfile.txt not in the monthly log files, but can't help on the cause. The incremental rain amount in the May and July log 5 min periods is 0.8 and 1.2 which I would think is quite small and not likely represent your logged rain rate. Incorrect Monthly and Alltime records can be edited quite easy in v.1.9.3.

Paul

Re: Vantage Vue extreme high rain rate?

Posted: Sun 21 Oct 2012 8:18 am
by steve
For Davis stations, Cumulus uses the rain rate calculated by the station. The station calculate the rain rate based on the times between two tips of the gauge. It is possible that you got two tips in short succession (for whatever reason, valid or otherwise) causing a high rate to be calculated. Even 0.8 mm of rain could cause a high rain rate if two tips were recorded close together, and 0.8 mm in 5 minutes (or less) does represent quite heavy rainfall. I think the console only keeps a record of daily high rain rates, so it's probably too late to see what the console thinks the high rate was?

Note that you are using an out-of-date build of 1.9.2; there may not be any significant changes between 1023 and 1032, but I can only support the latest build. If you have a crash, for example, it may not be possible for me to discover the reason.

Vantage Vue extreme high rain rate?

Posted: Sun 21 Oct 2012 8:35 pm
by Paragon
Thanks very much for your replies. 1440 mm/hr is 2 tips per second. Maybe the cause is a momentary phenomenon caused by the combination of dust in the cup, spider webs, heavy rain and a little swirl or something in the wind. If I edited the reading, what would I put? I'll leave it. The console shows the 2012 high rain rate as 1440 mm/hr.

I have noticed that every three months or a little less I have to clean out the rain gauge. Spider webs prevent tipping and dust gathers in it. The former causes low readings, the latter causes high readings. I wonder if there could be a resonance in the tipping caused by heavy rain and spider webs holding the cup.

I will upgrade to the latest build. Thanks very much.

Regards
Graham

Re: Vantage Vue extreme high rain rate?

Posted: Sun 21 Oct 2012 9:14 pm
by steve
Paragon wrote:The console shows the 2012 high rain rate as 1440 mm/hr.
So it's most likely an actual reading from the gauge. Either you did have a sudden brief downpour and the value is correct, or perhaps some issue with the gauge causing it to tip quickly (maybe in one direction only), similar to your suggestions.