A novel technique for measuring the rainfall from the rain noise

Abstract

It has been observed that if water droplets are allowed to fall with terminal velocity, on to the water trapped in the chamber of a specially designed sensor assembly, the resulting acoustic signal generated from the drop impact is wideband and extends up to 100 kHz. The acoustic energy of the signal in the low-frequency range is seen to be vis-a-vis correlated to the kinetic energy of the drops. Such an assembly is exposed to the rain to pick up the rain-generated noise. The energy of the rain-generated noise is seen to be proportional to the kinetic energy of the rain. From the rain kinetic energy–intensity relationship, the rainfall rate is computed. This paper presents an experimental procedure for estimating the rain intensity from the rain generated underwater noise captured by the sensor assembly. Experiment has been carried out for various rainfall rates and the computed rain intensities were compared with the ones measured with a tipping bucket rain gauge. The results and inferences suggest that this approach is a simple, cost effective and computationally efficient technique to measure the kinetic energy of rain as well as compute the rainfall rate.