Activity: Talk or presentation › Talk or presentation at a conference
Drop size distributions are often assumed to follow a generalized gamma function, characterized by one parameter, Λ, . In principle, this Λ can be estimated by measuring the arrival rate of raindrops. The arrival rate should follow a Poisson distribution. By measuring the distribution of the time intervals between drops arriving at a certain surface area, one should not only be able to estimate the arrival rate but also the robustness of the underlying assumption concerning steady state. It is important to note that many rainfall radar systems also assume fixeddrop size distributions, and associated arrival rates, to derive rainfall rates. By testing these relationships with a simple device, we will be able to improve both land-based and space-based radar rainfall estimates.
Here, an open-hardware sensor design is presented, consisting of a 3D printed housing for a piezoelectric element, some simple electronics and an Arduino. The target audience for this device are citizen scientists who want to contribute to collecting rainfall information beyond the standard rain gauge. The core of the sensor is a simple piezo-buzzer, as found in many devices such as watches and fire alarms. When a raindrop falls on a piezo-buzzer, a small voltage is generated , which can be used to register the drop's arrival time. By registering the intervals between raindrops, the associated Poisson distribution can be estimated.
In addition to the hardware, we will present the first results of a measuring campaign in Myanmar that will have ran from August to October 2017.
All design files and descriptions are available through GitHub: https://github.com/nvandegiesen/Intervalometer.
This research is partially supported through the TWIGA project, funded by the European Commission's H2020 program under call SC5-18-2017 ‘Novel in-situ observation systems’.
Reference : Uijlenhoet, R., and J. N. M. Stricker. "A consistent rainfall parameterization based on the exponential raindrop size distribution." Journal of Hydrology 218, no. 3 (1999): 101-127.