The SPectrometer for Ice Nuclei (SPIN): A new instrument to investigate ice nucleation

The SPectrometer for Ice Nuclei (SPIN) is a new commercially available ice nuclei counter manufactured by Droplet Measurement Technologies in Boulder, CO. SPIN is a continuous flow diffusion chamber with parallel plate geometry similar to the Zurich Ice Nucleation Chamber (ZINC) (Stetzer et al., 2007) and Portable Ice Nuclei Chamber (PINC) (Chou et al., 2011). It creates supersaturation conditions by coating two parallel plates with ice, holding them at different temperatures (both below 0ºC), and flowing an aerosol stream in the center of a sheath flow between the walls. After flowing through the main chamber, the air stream enters an isothermal evaporation section to evaporate liquid droplets. It then passes through a linear depolarization optical particle counter for particle, droplet, and ice counting. The instrument can be operated at aerosol temperatures as low as -55ºC and ice supersaturations exceeding 60%. This study characterizes the behavior of the SPIN chamber and reports data that validate its performance. In particular, ammonium sulfate experiments are used to compare the deliquescence and homogeneous freezing points reported by SPIN to literature values. Also, silver iodide and NX illite particles are used to investigate the heterogeneous ice nucleation onset conditions (with an ice fraction of 1%) for comparison to literature.

References:

Chou et al., Ice nuclei properties within a Saharan dust event at the Jungfraujoch in the Swiss Alps. Atmospheric Chemistry and Physics, 2011.

Stetzer et al., The Zurich Ice Nucleation Chamber (ZINC)-A New Instrument to Investigate Atmospheric Ice Formation. Aerosol Science and Technology, 2008.