Rainfall - Tipping bucket (Davis/Hobo)
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
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.
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 0.2mm can be significant!)
- Check out the "Things that went wrong"-Story of the Month July for problems when downlodading data with the optical shuttle
Links
Projects that used the above equipment
Other related web sites