Laser-Based Rain-Drop Sensing for Wind Error Correction in Rainfall Measurements

Wind significantly affects the accuracy of rainfall measurements, making high-resolution droplet and wind data essential for correcting undercatch errors. This paper introduces a cost-effective, laser-based optical sensor system designed for integration with tipping-bucket rain gauges. This detects rain-drop size and distribution as droplets pass through a laser beam, providing droplet data to improve correction of wind-induced undercatch errors. The system employs a semiconductor laser, photodiode arrays, and analog signal processing to detect optical signal variations caused by passing droplets. These variations are analysed using a neural network (NN) algorithm to estimate droplet characteristics. The proposed sensor system achieves a droplet size estimation deviation of just 0.475%, and a distribution error of 3%, highlighting its reliability and affordability for enhancing wind correction in rainfall monitoring.