A relatively new instrument on the market of Present Weather Sensors is the disdrometer from Thies (Laser Precipitation Monitor). In this instrument, precipitation particles falling through an infrared light beam lead to a reduction of the light intensity depending on the particle sizes. The duration of the reduction contains information on the fall speed of the particles. By comparing these parameters with known statistics for the various precipitation types, the precipitation type is determined.
In a test set-up of the German Weather Service (DWD), the precipitation type of the disdrometer is compared to an observer and to the Vaisala FD12P Present Weather Sensor. During the intercomparison, both rain and snow occurred allowing for a good data set. Results show that the disdrometer performs about the same as the FD12P when compared with the observer. Interestingly, the difference between the instruments individually is larger.
Based on these results (and an interesting price tag) further tests will take place, also under weather conditions in The Netherlands.
HI Bloemink, E Lanzinger. Precipitation type from the Thies disdrometer
2005, 2005, WMO