Institute for Atmospheric and Climate Science

Optical snow spectrometer

ETH Doppler Radar

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Optical snow spectrometer

The properties of snowflakes such as their size distribution, fall velocity, axial ratio or their orientation when falling are important in modelling precipitation processes or in interpreting returned radar power, especially of polarized radar. During the last decade, ground-based optical instruments for the measurement of hydrometeors have been developed at the IACETH. The first instrument worked with one light beam and it was possible to record the size, shape and an estimation of the fall velocity of each hydrometeor. The newly developed instrument works with two light beams which are vertically slightly offset. Thus, two images are recorded of each particle which can be used to calculate, in addition to the other properties, the exact fall velocity of the snowflakes. Hydrometeors can be recorded in the size range of 0.15 mm to 76 mm which includes the very large snowflakes falling within or close to the melting layer without truncating their image.

Contact: Raphael Schefold


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