A new thermal gradient ice nucleation diffusion chamber instrument: design, development and first results using Saharan mineral dust

Abstract

Abstract. A new Thermal Gradient ice nucleation DiffusionChamber (TGDC) capable of investigating ice nucleation efficiency of atmospherically important aerosols, termed Ice Nuclei (IN), has been designed, constructed and validated. The TGDC can produce a range of supersaturations with respect to ice (SS i ) over the temperature range of −10 to −34 • C for sufficiently long time needed to observe the ice nucleation by the particles. The novel aspect of this new TGDC is that the chamber is run in static mode with aerosol particles supported on a Teflon substrate, which can be raised and lowered in a controlled way through the SS i profile within the chamber, and nucleation events are directly observed using digital photography. The TGDC consists of two ice coated plates to which a thermal gradient is applied to produce the range of SS i . The design of the TGDC gives the ability to understand time-related ice nucleation event information and to perform experiments at different temperatures and SS i conditions for different IN without changing the thermal gradient within the TGDC. The temperature and SS i conditions of the experimental system are validated by observing (NH 4 ) 2 SO 4 deliquescence and the results are in good agreement with the literature data. First results are presented of the onset ice nucleation for mineral dust sampled from the Saharan Desert, including images of nucleation and statistical distributions of onset ice nucleation SS i as a function of temperature. This paper illustrates how useful this new TGDC is for process level studies of ice nucleation and more experimental investigations are needed to better quantify the role of ice formation in the atmosphere.

Ice nucleation properties of mineral dust particles: determination of onset RH<sub><i>i</i></sub>, IN active fraction, nucleation time-lag, and the effect of active sites on contact angles

“…The thickness of ice layers is maintained constant by freezing a known quantity of deionized water (18 M ). A detailed procedure of preparing the ice layers is outlined in Kulkarni et al (2009). An average ice layer thickness of 4 mm was used to produce a 12 mm gap between the top and bottom ice layers.…”

“…-h = the height between the ice layers in mm, Kulkarni et al (2009) for RH i calibration process. The onset of ice formation is related to the temperature and RH i conditions at which ice was first observed on any dust particle under the observation area of the microscope.…”

“…In the present study, using a newly developed experimental set-up (Kulkarni et al, 2009), we have investigated the ice nucleation efficiency of natural mineral dust particles as a function of temperature, saturation ratio and nucleation time. In Sect.…”

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

“…The Portable Ice Nucleation Chamber (PINC), designed as a field-deployable version of the ZINC, has since been used to conduct several laboratory and field studies (Chou et al, 2011Kanji et al, 2013). In addition, other research groups have also developed similar chambers (Kanji et al, 2009;Kulkarni et al, 2009;Friedman et al, 2013;Jones et al 2011;Saito et al, 2011). Adapting the parallel plate design and other features from the ZINC and PINC chambers, the SPectrometer for Ice Nuclei (SPIN) is a commercially available ice nuclei counter manufactured by Droplet Measurement Technologies (DMT) in Boulder, CO.…”

Manchester Ice Nucleus Counter (MINC) measurements from the 2007 International workshop on Comparing Ice nucleation Measuring Systems (ICIS-2007)

“…Several instrument exist that are capable of measuring ice nucleation properties, these include static diffusion chambers (e.g. Kanji and Abbatt, 2006;Knopf and Koop, 2006;Dymarska et al, 2006, Kulkarni et al, 2009) and continuous flow diffusion chambers (e.g. Stetzer et al, 2008;Rogers 1988).…”