The Feasibility of Using a Hot-Film Anemometer in the Rain

Abstract

Cylindrical, platinum-coated, hot-film anemometers were struck with a series of individual drops of water while immersed in controlled airflows with velocities ranging from 0.3 to 5.0 m s?1. Subjecting the sensor to water drops caused slight, but permanent, changes in calibration. In an effort to overcome calibration changes following drop impacts, a Teflon-coated sensor was also tested. A filtering algorithm was devised to remove drop-caused spikes in the recorded time series. An average spike duration of 0.32 s per drop impact was found, and maximum record loss was estimated to be 1.7% for rainfall rates less than 30 mm h?1.