View source for Rainfall - Tipping bucket (Davis/Hobo)

[[Image:raingauge.jpg|right|150px|Rainfall - Tipping Bucket]]
==Parameter to be measured:==
*Rainfall (if heated also snow fall)
*Temperature

==Method:==
Tipping bucket raingauge
==Equipment:==
Raingauge: Davis

Logger: Hobo Event Logger

==Advantages:==
*Cheap
*Easy to install
*Logging of 8000 events possible
*Nice small logger in water tight PVC casing
*Sturdy: we have operated 9 gauges for 11 year (temperatures -10 - 40°C) without major flaws except for clogging by dust and bird droppings. One logger even survived a longer time of being submersed (funnel had turned upsidedown) with water in the logger case. after drying, if still worked, but data had been lost.
*Low consumption: some logger operated for more than 3 years on a single battery, even with hourly temperature recordings. Even when the software raises a battery warning, things often work well. Even if communication is not possible anymore, values are usually still being recorded and can be retrieved after battery replacement.

==Disadvantages:==
*after two years the logger clock of the Hobo loggers seemed to have some problems in some cases
*read-out procedure sensitive to sunlight (see below)
*The reed relay (magnetic switch below axis) seems to fail after some use (either the contacts don't close at all or with an increased resistance that prevents the Hobo logger from detecting this as an event). Using bicycle computer sensors (those of SIGMA computers fit exactly) provide an easy and probably more robust fix than the original.
[[Image:Davis_sigma.jpg]]

==Problems/Questions:==
*the tipping bucket raingauge needs to be calibrated or the exact volume per event needs to be determined by dripping a specified amount of water into the raingauge and then deviding by the number of "events" measured. The volume per event is different for each gauge. (The difference from the specified 0.2 mm can be significant!)
*Check out the [[The "Things that went wrong"-Story of the Month|"Things that went wrong"-Story of the Month July]] for problems when downlodading data with the optical shuttle
*There is yellow plastic sheet inside the casing. When accidentally aligning it wrongly during battery replacement, the optical communicition with the logger may be blocked.
*Hoboware is not strictly downwards compatible: A logger started with a higher version may not be readable with a lower one.
*the rubber sealing on the logger suggests water proofness, which is, in fact, not guranteed.

==Links==
Projects that used the above equipment
* [http://brandenburg.geoecology.uni-potsdam.de/projekte/malalcahuello/index.php Malalcahuello]
* [http://www.grosshang.de/index.php/naturalslope.html Natural Slope]
* [http://brandenburg.geoecology.uni-potsdam.de/projekte/opaque/ OPAQUE]
* [https://www.gfz-potsdam.de/en/section/hydrology/projects/completed-projects/sesam/ SESAM]
* [https://www.pyrophob.de/ PYROPHOB]

Other related web sites

==References==

[[Category:Equipment]]
[[Category:Rainfall]]
[[Category:Temperature]]