Ice nucleation of bare and sulfuric acid‐coated mineral dust particles and implication for cloud properties

Abstract

Ice nucleation properties of atmospherically relevant dust minerals coated with soluble materialsare not yet well understood. We determined ice nucleation ability of bare and sulfuric acid-coated mineral dust particles as a function of temperature (À25 to À35°C) and relative humidity with respect to water (RH w ; 75 to 110%) for five different mineral dust types: (1) Arizona test dust, (2) illite, (3) montmorillonite, (4) K-feldspar, and (5) quartz. The particles were dry dispersed and size selected at 200 nm, and we determined the fraction of dust particles nucleating ice at various temperatures and RH w . Under water-subsaturated conditions, compared to bare dust particles, we found that coated particles showed a reduction in their ice nucleation ability. Under water-supersaturated conditions, however, we did not observe a significant coating effect (i.e., the bare and coated dust particles had nearly similar nucleating properties). X-ray diffraction patterns of the coated particles indicated that acid treatment altered the crystalline nature of the surface and caused structural disorder; thus, we concluded that the lack of such structured order reduced the ice nucleation efficiency of the coated particles in deposition ice nucleation mode. In addition, our single column model results show that coated particles significantly modify cloud properties such as ice crystal number concentration and ice water content compared to bare particles in water-subsaturated conditions. However, in water-supersaturated conditions, cloud properties differ only at warmer temperatures. These modeling results imply that future aged dust particle simulations should implement coating parameterizations to accurately predict cloud properties.

Leipzig Ice Nucleation chamber Comparison (LINC): intercomparison of four online ice nucleation counters

“…4b), but at 243 K a higher RH w is needed to reach AF = 10 −3 . Kulkarni et al (2014) also reported a reduction in the ice nucleation ability of 200 nm particles of a K-feldspar sample after coating with sulfuric acid. A general reduction in the ice nucleation ability agrees with the immersion freezing measurements on microcline after treatment with nitric acid presented in this work, but sulfuric acid treatment was not tested with PINC.…”

Characterization of individual ice residual particles by the single droplet freezing method: a case study in the Asian dust outflow region

“…However, the situation is even more complex in the ambient atmosphere, where particles are often present as complex mixtures of different compounds and minerals. Although recent laboratory experiments have considered the influence of aerosol mixing states (Sullivan et al, 2010;Kulkarni et al, 2014;Augustin-Bauditz et al, 2016), the complexity of the atmosphere has not yet been fully represented.…”

“…The internal mixing of particles is an important factor that contributes to the complexity of atmospheric aerosol particles. Although efforts have been made to address the effects of internal mixing on the IN activity of aerosols under conditions relevant for the mixed-phase cloud formation (Sullivan et al, 2010;Kulkarni et al, 2014;Augustin-Bauditz et al, 2016), the complexity of the ambient aerosol has not yet been fully represented by the laboratory-generated aerosols. Therefore, detailed investigation based on the individual particle analysis is necessary to relate the internal mixing state of aerosols in the actual atmosphere and their IN activity.…”

Enhanced ice nucleation efficiency of microcline immersed in dilute NH<sub>3</sub> and NH<sub>4</sub><sup>+</sup>-containing solutions

“…Deposition and immersion nucleation experiments showed reduced IN efficiency for sulfuric acid-coated feldspar particles (Kulkarni et al, 2014). Zolles et al (2015) reported a decreased IN efficiency for enzyme-treated K-feldspar but after heating the efficiency was restored to the original value.…”

“…In this case, active sites might remain intact but disabled to act as INP because of the organic cover. In the absence of surface chemical reactions, the chemical coating might dissolve during cloud droplet activation releasing the mineral surface again restoring the 105 ice-nucleating ability (Sullivan et al, 2010b;Tobo et al, 2012;Kulkarni et al, 2014;Wex et al, 2014).…”