Preprints
https://doi.org/10.5194/acp-2021-179
https://doi.org/10.5194/acp-2021-179

  06 Apr 2021

06 Apr 2021

Review status: this preprint is currently under review for the journal ACP.

Measurement report: Mass and Density of Individual Frozen Hydrometeors

Karlie Rees1, Dhiraj Singh2, Eric Pardyjak2, and Timothy Garrett1 Karlie Rees et al.
  • 1Department of Atmospheric Sciences, Salt Lake City, UT, USA
  • 2Department of Mechanical Engineering, Salt Lake City, UT, USA

Abstract. A new precipitation sensor, the Differential Emissivity Imaging Disdrometer (DEID), is used to provide the first continuous measurements of the mass, diameter, and density of individual hydrometeors. The DEID consists of an infrared camera pointed at a heated aluminum plate. It exploits the contrasting thermal emissivity of water and metal to determine individual particle mass by assuming that energy is conserved during the transfer of heat from the plate to the particle during evaporation. Particle density is determined from a combination of particle mass and morphology. A Multi-Angle Snowflake Camera (MASC) was deployed alongside the DEID to provide refined imagery of particle size and shape. Broad consistency is found between derived mass-diameter and density-diameter relationships and those obtained in prior studies. However, DEID measurements show a generally weaker dependence with size for hydrometeor density and a stronger dependence for aggregate snowflake mass.

Karlie Rees et al.

Status: open (until 01 Jun 2021)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse

Karlie Rees et al.

Karlie Rees et al.

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Short summary
An old problem for accurately predicting weather and climate is knowing the mass and density of snowflakes as a function of their size. Few measurements have been obtained because snowflakes are so small and fragile. The most widely used sample is of just 376 snowflakes obtained in the early 1970s in Washington State. We developed a new instrument for automatic measurement of snowflake mass and density. Our analysis shows that snowflakes have a lower density than is often assumed.
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