Quantifying and Parameterizing Mixed-Phase Microphysical Properties Using Novel Measurement Technologies

Current systems used for weather observations have a difficult time discriminating between precipitation types in cold weather. This uncertainty affects societally-relevant decisions about road maintenance, risk to electrical infrastructure, and even avalanche safety. Scientifically, the lack of observations of the density of frozen precipitation impacts research on how winter precipitation is viewed by weather radars and how best to simulate winter precipitation in weather models. This award will allow for the continued development and testing of a new instrument that can measure individual particles and assess their size and mass. The Differential Emissivity Imaging Disdrometer (DEID) consists of a heated aluminum plate and an infrared camera. The plate is maintained at a temperature just below the boiling point of water and the camera images precipitation particles that fall on the plate. By measuring the temperature, area, melt time, and evaporation rate of each particle, the mass of the particle can be determined and density relationships calculated. The new research under this award will add and improve techniques to distinguish precipitation phase and measure the mass of the particles. Laboratory measurements will be conducted using well-characterized spherical and non-spherical ice particles to ensure a successful comparison between the DEID and known masses of frozen, partially melted, and liquid precipitation. The DEID will also be deployed to an instrumented site near the University of Utah campus for field observations. The DEID measurements will be compared to a particle tracking velocimetry laser-camera system that can measure the size and phase (but not mass) of falling precipitation and a Multi-Angle Snowflake Camera to validate the DEID’s ability to quantity partially melted snowflakes. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.