Tipping bucket rain gauge quietly gains favor worldwide
November 15, 2017
The need to measure
People have been trying to measure rainfall for a long time. The first known rainfall records were kept by Ancient Greeks, beginning about 500 B.C. People in India began to record rainfall as early as 400 B.C.
In 1441 the Cheugugi was invented during the reign of King Sejong the Great of the Joseon Dynasty of Korea; it’s considered the first standardized rain gauge.
Then in 1662, Christopher Wren created the first tipping bucket rain gauge in Britain in collaboration with Robert Hooke.
Collaboration yields innovation
Our personal obsession with accurate and precise measurement of rainfall began in the 1980’s with a collaboration between Hydrological Services Australia and the Australian Bureau of Meteorology, which sought a more accurate and reliable rain gauge.
A key requirement was an instrument that could operate for extended periods in remote locations without failure. Three signature tipping bucket rain gauges were developed. Over the past 25 years, they have become the largest selling products worldwide in our hydromet sensor portfolio.
Many prestigious international agencies, such as the Australian Bureau of Meteorology, (U.S.) NOAA, Environment Canada, Cemaden Brazil, South African Weather Service, China Water, and the Thai Meteorological Department to name just a few, have made these rain gauges a keystone of their national rainfall measurement programs.
How does a tipping bucket rain gauge work?
This measuring device consists of a funnel-shaped collector, two small ‘buckets’ mounted on an axle like a seesaw, and an electronic reed switch. Rain enters the funnel and into one of the two buckets, which when full, tips the water into the base where it exits through a screened hole. Each bucket tip is registered by an electronic reed switch and recorded by the datalogger. Gauges are typically calibrated to tip at 0.01 inch, 0.2mm, 0.5mm or 1.0mm of rainfall.
Well-designed and quietly gaining favor worldwide
The TB3 and TB4 perform impressively in high intensity rainfall events. Robust, reliable and accurate with very stable calibration, these models deliver a better than 1% accuracy at rainfall rates up to 2” per hour. Its field proven reliability has been demonstrated world-wide in a range of extreme environments — and overcomes clogging (from pollen).
With TB6 model, now discontinued, Nashville Metro Water achieved an 81% reduction in the number of clogged rain gauges. How did this tipping bucket different from their previous device? The flat screen filter and the innovative finger filter on the tipping bucket rain gauge avoided mechanical fouling. The new device not only lower maintenance demands, but it improved rainfall measurement.
It’s all about the data
Here are 4 questions to answer before you purchase a tipping bucket rain gauge:
- Region: What is the expected range of intensities the rain gauge will measure?
- Accuracy: What level of accuracy is acceptable?
- Return Frequency: Up to what return frequency do you wish to measure accurately?
- Reliability: What is the expected level of reliability over time?
Tipping bucket rain gauges represent a tremendous advance in the ability to accurately measure rainfall in unattended environments and to be able to receive precise data in real time.