I’ve had a Davis VP2 in operation for about 9 months now. One issue I’ve noticed on about half a dozen occasions throughout the winter is the incorrect recording of 0.2mm of rain shortly after dawn on frosty mornings. I’m sure this is caused by cool moist air condensing overnight and freezing on the rain gauge funnel and then thawing as the sun comes up and dripping into the rain buckets before it evaporates, in just sufficient quantity to cause a tip and thus 0.2mm of rain to be recorded. The real giveaway is to watch the outside temperature. The rogue rainfall invariably coincides with the outside temperature climbing to just above freezing.
The station is situated in an open area on a pole 2m above the high point of my house roof. I’m surprised others have not observed on similar behaviour. For now, the only solution I can think of is to manually delete that incorrect 0.2mm rain, which in itself is a pain to remember to do and moreover I can’t see a way of doing this until the day after the event, so that when this problem occurs, my site can be recording 0.2mm rain on a perfect blue sky winter’s day, until the following day when I correct my records (assuming I remember to do this).
Well, so there is :-). Thanks Brian, I’ve now ticked that option. One quick follow-up: What logic does this option use? Always ignore the first tip of the bucket on any given day? Only ignore the first tip if it occurs at a certain time of the day or within a certain temperature range? I’m wondering if selecting this option could artificially lower the actual amount of rainfall recorded? Or, if the current setting is “Always ignore the first tip of the bucket on any given day”, perhaps it could be refined to take account of temp/time of day.
I thought I had this problem recently but ended up with something like 2.5mm recorded at about 6:45 ~ sunrise, but it was far more than one tip expected. Went out to have a look and a spider was doing a merry “rain-dance” in there probably spinning a web
It was difficult to remove from the files afterwards, it ended up adding itself to the next day somehow as it was resident in the ini file I expect as a current value - I even shut WD down while I did the error corrections in the 82007lg.txt file itself manually, restarted and the error had transferred to the new day… The import Log and turn into graphs, 24hr graph, cleared the specific day but Wd restarted carrying the old value
The other system of editing rainfall, wind etc loads in the whole month. Can we have an option to just load in the last 24hrs? It loses a start reference point and you end up with a row of data zeros in the data fields at the top after clicking on a line, or selecting a known day/time…
