Abstract
Present weather sensors are becoming increasingly important as a means to augment networks of automated weather stations and extend the capability of manned observations. The classification of hydrometeors is one of the principal tasks that is addressed by present weather sensors. In this paper, we discuss a new laser-based technology for this purpose. The system improves upon current precipitation monitors by using a derivative of phase Doppler anemometry techniques to accurately determine particle speed and size. The instrument is also capable of distinguishing between liquid droplets and solid polycrystalline hydrometeors and can be used to estimate visibility. The incorporation of this technology into a meteorological station with other sensors, such as temperature and relative humidity probes, leads to the accurate classification of particle type. The example data shown are taken from tests in Leicestershire, England and Utah, USA and show the differences between solid and liquid precipitation events.