Ice nucleation of desert dust and other mineral aerosols: processes and parameterisations

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Quentin Phillips
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Steinke and Robert Wagner - Atmosphärische Aerosolforschung (IMK-AAF) KIT Universität des

1 Ice nucleation of desert dust and other mineral aerosols: processes and parameterisations Ottmar Möhler, Naruki Hiranuma, Kristina Höhler, Corinna Hoose, Monika Niemand, Isabelle Steinke and Robert Wagner - Atmosphärische Aerosolforschung (IMK-AAF) KIT Universität des Landes Baden-Württemberg und nationales Forschungszentrum in der Helmholtz-Gemeinschaft

2 IMK-AAF: From single droplets to cloud ensembles AIDA-micro AIDA-classic AIDA-dynamic AIDA-alpine m s spatial scale temporal scale km day 2

3 Aerosol Interactions and Dynamics in the Atmosphere Major research topics: Temperature dependent formation of secondary organic aerosol Aerosol-cloud processes Ice crystal growth and habit 3

4 Temperature (K) Aerosol-cloud processes in the troposphere In situ aerosol formation sulphuric acid, organics Aged aerosol coating Ice saturation ratio immersion freezing of solutions deposition nucleation homogeneous freezing of solutions 230 Most efficient IN and CCN removed by Precipitation? CCN Solid particles, ice nucei Soluble particles (sulphates, nitrates, organics) immersion/ condensation freezing contact freezing homogeneous freezing of cloud droplets 4

8 2 immersion freezing of solutions deposition nucleation homogeneous freezing of solutions 230 Most efficient IN and CCN removed

5 Background Heterogeneous IN is a complex multi-parameter problem Hoose and Möhler, 2012 Variability of onset conditions (see figure) must be due to aerosol properties Recent attempts to formulate heterogeneous ice formation as function of aerosol properties: Empirical approaches (Diehl et al, 2006; Phillips et al., 2008) Surface nucleation rates (Hoose et al., 2010; Barahona, 2012; Broadley et al., 2012) Surface site densities (Connolly et al., 2009, Niemand et al., 2012) soot dust bacteria Number of aerosols larger than 0.5 µm (DeMott et al., 2010) 5

approaches (Diehl et al, 2006; Phillips et al., 2008) Surface nucleation rates (Hoose et al., 2010; Barahona, 2012; Broadley et al.

6 Typical AIDA expansion experiment with dust aerosol 6

7 AIDA immersion freezing experiments with desert dust Dust samples used in AIDA experiments: Arizona test dust (ATD) Asian dust (AD) Saharan dust (SD) Canary island dust (CD) Israel dust (ID) All samples are dispersed from dry powder aerosol droplets ice Measured data: n ice : number concentration of ice (frozen droplets) as function of T s ae : aerosol surface area from fit to surface area distribution INAS n ( T) s nice ( T) s ae Number of ice-active sites per aerosol surface area of particles immersed in droplets aerosol surface area distribution 7

ice : number concentration of ice (frozen droplets) as function of T s ae : aerosol surface area from fit to surface area distribution

8 INAS density for dust immersion freezing Niemand et al.,

9 Case study: Saharan dust outbreak during May 2008 DREAM model result of vertically integrated dust mass load in µg m2 at 12 GMT of a) May 25 b) May 27 c) May 29 d) May 31 Klein et al.,

10 Comparison of modelled and measured IN concentrations 10

65 10 6 at -25 C ~1.4 Si oxide Al oxide Si oxide 2 Illite CMS (IMt-1, Clay Mineral Society) Illite 85-90%, Quartz 10-15% (Manufacture data) 0.5 μm 31.7 2.6 10 10 at -25 C ~1.

11 No. Sample (Supplier) Major Compositions SEM Image BET Surface, m 2 g -1 Density, g cm -3 n s, immersion, m -2 DSF Polygon Rep. (Murray et al., 2012) 1 Illite NX (NX Nanopowder, Arginotec) Illite 59%, Kaolinite 9%, Quartz 10%, Feldspar 18%, Calcite 3% (XRD this study) 2 μm ± 0.7 (Broadley et al., 2012) ± 1.5 (this study) at -25 C ~1.4 Si oxide Al oxide Si oxide 2 Illite CMS (IMt-1, Clay Mineral Society) Illite 85-90%, Quartz 10-15% (Manufacture data) 0.5 μm at -25 C ~1.4 K 3 Kaolinite Fluka (Fluka) Illite 4%, Kaolinite 82%, Anatase 1%, Quartz 5%, Feldspar 7% (XRD this study) 0.5 μm 3 to 6 times larger than geometric surface basis (Welti et al., 2012) 8.6 ± 0.2 (this study) 2.6 2x10 11 at -25 C Si oxide Al oxide 4 Kaolinite CMS (KGa-1b, Clay Mineral Society) Kaolinite 97%, Anatase 3% (XRD this study) 1 μm 11.8 ± 0.8 (Murray et al., 2011) 12.2 ± 0.01 (this study) 2.6 (Hoffmann et al., 2013) at -25 C 5 K-feldspar Leeds (University of Leeds) K 2 O, Al 2 O 3, SiO 2 (Bailey, 1969) (Bailey, 1969) 5x10 11 at -25 C Si oxide 6 K-feldspar Darmstadt (Technical University of Darmstadt) K 2 O, Al 2 O 3, SiO 2 (Bailey, 1969) 76% microcline, 24% albite (XRD this study) (Bailey, 1969) Al oxide Cation 7 Snomax (P. Syringae bacteria) Protein 54%, Carbohydrates 15%, Nucleic Acids 10%, Nutrients 16%,Trace Mineral/Metal 5% (Manufacture data) 1 μm (Möhler et al., 2008) 5x10 10 at -10 C ± (Hoffmann et al., 2013) 5x10 8 at -34 C μm 8 Hematite Fe 2 O 3 (Sugimoto, 1992) 0.5 μm 3.7 ± (Hoffmann et al., 2013) 6x10 9 at -34 C

12 Monodisperse, pseudo-cubic hematite particles cubic milled 12

13 INAS density of pristine and milled hematite particles Milled particles have order of magnitude higher INAS density BET surface only factor of 2 higher Influence of surface cracks, edges,? Is IN activity of other milled samples also enhanced? 13

surface only factor of 2 higher Influence of surface cracks,

14 Coating with secondary organic aerosol mass (SOM) AIDA in situ coating with SOM from reaction O 3 + a-pinene Almost no or very little effect on immersion freezing of desert dusts at -25 to -30 C, also from CFDC and PINC measurements Kanji et al., paper in preparation 14

little effect on immersion freezing of desert dusts at -25 to -30

15 Immersion freezing of volcanic ash particles Steinke et al., ACP,

16 Summary INAS approach is appropriate to parameterise immersion freezing of fresh dust aerosol Easy to use in models Application to Saharan dust outbreak to Europe in 2008 Good agreement with parameterisation from DeMott et al., 2010 Surface processing (milling) of hematite particles enhances IN activity IN results for artificially grounded and processed samples should be treated with care Surface coating has little effect on immersion freezing, but strong effect on deposition nucleation More experiments with realistic aerosol mixtures Interested in any dust surface or even better aerosol samples for laboratory cloud studies 16

, 2010 Surface processing (milling) of hematite particles enhances IN activity IN results for artificially grounded and processed samples should be treated

17 Acknowledgements AIDA work was partly funded by Helmholtz Association Virtual Institute on Aerosol-Cloud Interactions (VI-ACI) Research Programme Atmosphere and Climate (ATMO) German Research Foundation Research Unit INUIT (FOR 1525) 17