Abstract
The WeIzmann Supercooled Droplets Observation on Microarray (WISDOM) is a new setup for studying ice nucleation in an array of monodisperse droplets for atmospheric implications. WISDOM combines microfluidics techniques for droplets production and a cryo-optic stage for observation and characterization of freezing events of individual droplets. This setup is designed to explore heterogeneous ice nucleation in the immersion freezing mode, down to the homogeneous freezing of water (235 K) in various cooling rates (typically 0.1-10 K min(-1)). It can also be used for studying homogeneous freezing of aqueous solutions in colder temperatures. Frozen fraction, ice nucleation active surface site densities and freezing kinetics can be obtained from WISDOM measurements for hundreds of individual droplets in a single freezing experiment. Calibration experiments using eutectic solutions and previously studied materials are described. WISDOM also allows repeatable cycles of cooling and heating for the same array of droplets. This paper describes the WISDOM setup, its temperature calibration, validation experiments and measurement uncertainties. Finally, application of WISDOM to study the ice nucleating particle (INP) properties of size-selected ambient Saharan dust particles is presented.
Original language | English |
---|---|
Pages (from-to) | 233-248 |
Number of pages | 16 |
Journal | Atmospheric Measurement Techniques |
Volume | 11 |
Issue number | 1 |
DOIs | |
Publication status | Published - 12 Jan 2018 |
Funding
We gratefully acknowledge support from the Ice Nuclei Research Unit (INUIT) of the German DFG, to The Helen Kimmel Center for Planetary Sciences, The de Botton Center for Marine Sciences and the Weizmann–UK Making Connections program for funding this work. We also thank Daniel Knopf, Carsten Budke, Thomas Koop, Ido Braslavski, and Nir Freidman for their advices as well as Ben Murray and Heinz Bingemer for sharing the K-feldspar and illite-NX powder standards.