Thursday, 6 June 2002: 11:45 AM
A New Groundbased Precipitation Spectrometer: The Meteorological Particle Sensor (MPS)
A new instrument to characterize precipitation has been recently developed and tested operationally. This instrument, the Meteorological Particle Sensor (MPS) measures the concentration, size, shape, fall velocity and arrival times of individual precipitation particles over the size range from 0.05 mm to 3.1 mm. The high resolution measurements from the MPS provide more information on drizzle and precipitation characteristics than can be measured with other commercially available disdrometers. In particular, particle-by-particle measurements of fall velocity provide more accurate information on rainrate as a function of particle size and the arrival time information allows an in-depth study of non-Poissonian distributions of particles.
The MPS was operated by the National Weather Service from January 30 to May 21, 2001 in a test program to compare the results of the MPS with other rain gages, as well as with human observations. Fall velocity measurements are in very good agreement with laboratory measurements by Gunn and Kinzer; however, anomalously high velocities of particles smaller than 0.3 mm suggest drop break-up. Multi-modal size distributions also suggest that drop break-up is occurring.
Selected measurements will be presented that illustrate the capabilities of the MPS and that preview some interesting precipitation events that are currently under evaluation to study the small-scale inhomogeneities of rain down-burst events.