Gauge for Continuously Measuring Rate of Rainfall

Abstract

A gauge for continuously measuring rainfall rate is discussed. In this gauge, water flows through a channel type capacitor which is coupled to an oscillator, thus the frequency of the output voltage changes with rain rate. The calibration curve can be expressed mathematically as the sum of two exponentials, f=f₀½[exp(−K₁R) +exp(−K₂R)] where f₀ is the frequency corresponding to dry condition, R the rain rate, and K₁ and K₂ are constants. One hundred gauges have been fabricated and calibrated, and statistics of these calibrations are presented. Based upon the measured data, capacitance rain gauges are found suitable for situations where continuous rainfall rate data are desired. The output of the gauge is in a form readily adapted for computer reduction.