92nd American Meteorological Society Annual Meeting (January 22-26, 2012)

Monday, 23 January 2012
A New Instrument for High-Speed, High Resolution Stereoscopic Photography of Falling Hydrometeors with Simultaneous Measurement of Fallspeed
Hall E (New Orleans Convention Center )
Timothy J. Garrett, Univ. of Utah, Salt Lake City, UT; and C. Fallgatter

We introduce a new instrument called the Multi-Angle Snowflake Camera (MASC). The MASC provides <30 micron resolution stereoscopic photographic images of individual large falling hydrometeors, along with their fallspeed. Previously, manual photography of hydrometeors has required initial collection on a flat surface, a process that is somewhat subjective and remarkably finicky due to the fragile nature of the particles. Alternatively, instruments such as the 2DVD are automated, leave the particle untouched and provide fallspeed data, but provide only 200 micron resolution silhouettes, which are insufficient to definitively assess the extent of riming on frozen hydrometeors. The MASC is like the 2DVD but uses a sensitive IR motion sensor for a trigger and actually photographs the particle surface from multiple angles. Field testing in April 2011 provided beautiful images and fallspeed data, suggesting that MASC measurements may lead to improved parameterizations for aggregation, riming and precipitation in cold-storm weather models. In winter 2011 and 2012, the NSF supported Wasatch Hydrometeor Aggregation and Riming Experiment (WASHARX) is deploying the MASC, an FSSP-100, meteorological instrumentation and a vertically pointing MRR radar to Alta Ski Area near Salt Lake City with the goal of obtaining long-term continuous measurements of hydrometeor development and fallspeed.

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