A comprehensive laboratory study on the immersion freezing behavior of illite NX particles: a comparison of 17 ice nucleation measurement techniques

Abstract

Abstract. Immersion freezing is the most relevant heterogeneous ice nucleation mechanism through which ice crystals are formed in mixed-phase clouds. In recent years, an increasing number of laboratory experiments utilizing a variety of instruments have examined immersion freezing activity of atmospherically relevant ice-nucleating particles. However, an intercomparison of these laboratory results is a difficult task because investigators have used different ice nucleation (IN) measurement methods to produce these results. A remaining challenge is to explore the sensitivity and accuracy of these techniques and to understand how the IN results are potentially influenced or biased by experimental parameters associated with these techniques.Within the framework of INUIT (Ice Nuclei Research Unit), we distributed an illite-rich sample (illite NX) as a representative surrogate for atmospheric mineral dust particles to investigators to perform immersion freezing experiments using different IN measurement methods and to obtain Published by Copernicus Publications on behalf of the European Geosciences Union. N. Hiranuma et al.: A comparison of 17 IN measurement techniquesIN data as a function of particle concentration, temperature (T ), cooling rate and nucleation time. A total of 17 measurement methods were involved in the data intercomparison. Experiments with seven instruments started with the test sample pre-suspended in water before cooling, while 10 other instruments employed water vapor condensation onto drydispersed particles followed by immersion freezing. The resulting comprehensive immersion freezing data set was evaluated using the ice nucleation active surface-site density, n s , to develop a representative n s (T ) spectrum that spans a wide temperature range (−37 • C < T < −11 • C) and covers 9 orders of magnitude in n s .In general, the 17 immersion freezing measurement techniques deviate, within a range of about 8 • C in terms of temperature, by 3 orders of magnitude with respect to n s . In addition, we show evidence that the immersion freezing efficiency expressed in n s of illite NX particles is relatively independent of droplet size, particle mass in suspension, particle size and cooling rate during freezing. A strong temperature dependence and weak time and size dependence of the immersion freezing efficiency of illite-rich clay mineral particles enabled the n s parameterization solely as a function of temperature. We also characterized the n s (T ) spectra and identified a section with a steep slope between −20 and −27 • C, where a large fraction of active sites of our test dust may trigger immersion freezing. This slope was followed by a region with a gentler slope at temperatures below −27 • C. While the agreement between different instruments was reasonable below ∼ −27 • C, there seemed to be a different trend in the temperature-dependent ice nucleation activity from the suspension and dry-dispersed particle measurements for this mineral dust, in particular at higher temperatures. For instance,...

Deposition and immersion-mode nucleation of ice by three distinct samples of volcanic ash

“…Thus, for immersion freezing, we find that the Raman microscope cold stage setup can be used to intercompare inherent immersion freezing abilities of particle types to other instruments under the singular or modified singular approximation. This ability of the Raman microscope cold stage to determine the inherent immersion freezing ability of NX-Illite nanopowder has also been verified (Hiranuma et al, 2015).…”

“…For each ash, the BET specific surface area was used as determined in this study (Table 1). The modified singular approximation was not used because larger particle-to-particle variability of ice active sites is expected for these complex samples, limiting the importance of time dependence (Broadley et al, 2012;Hiranuma et al, 2015). As shown in Fig.…”

Online differentiation of mineral phase in aerosol particles by ion formation mechanism using a LAAP-TOF single-particle mass spectrometer

“…Single-particle measurements of T O / T SiO 3 (τ ) vs. the combined potassium and sodium content are shown in the top panel (a). Panel (b) reports the particle number fractions determined by the peak analysis classification method (grey bars), and bulk mass fractions of minerals reported by XRD analysis of illite NX from Hiranuma et al (2015), and IMt-2 and ISCz-1 from Vogt (2002) (red bars). ion formation time, ion trajectory through the ion optics, and temporal jitter of the timing electronics all contribute to differences in arrival times of a certain ion species at the TOF-MS detector.…”

“…Sample ISCz-1 is an example of a clay that consists of microscopic interlayers of illite and smectite clay minerals (ISCM). Recently, Broadley et al (2012) suggested illite NX (B+M Nottenkamper, Munich, Germany) as a suitable representation of ambient mineral dust sampled at remote locations and it has been used in numerous ice nucleation studies (Hiranuma et al, 2015). Illite NX is a clay-rich nanopowder that contains significant mineralogical impurities.…”

Pre-activation of ice-nucleating particles by the pore condensation and freezing mechanism

“…The intrinsic heterogeneous ice nucleation abilities of these substances have been characterised in previous AIDA measurement campaigns. The materials include: (i) an Illite NX sample (Arginotec, NX Nanopowder) that was recently distributed as a surrogate for natural desert dusts in a comprehensive laboratory study of ice nucleation measurement techniques (Hiranuma et al, 2015); (ii) a Saharan dust surface sample (SD2) collected about 50 km north of Cairo, Egypt ; (iii) an Israeli dust sample (ID) collected from Ramat Hasharon as sediment soil after a dust storm ; (iv) a Canary Island dust surface sample (CID) collected near the town of Mala on the Island of Lanzarote as a proxy for settled Saharan dust after airborne transport Koehler et al, 2010); (v) a volcanic ash surface sample (EY01) collected 58 km from the Eyjafjallajökull volcano on Iceland 2 days after a major eruption phase in April 2010 (Steinke et al, 2011); and (vi) Graphite Spark Generator (GSG) soot particles from a commercial graphite spark generator (GfG 1000, Palas) (Möhler et al, 2005).…”