Heterogeneous Freezing of Aqueous Particles Induced by Crystallized (NH4)2SO4, Ice, and Letovicite

Zuberi, B.; Bertram, Allan K.; Koop, Thomas; Molina, Luisa T.; Molina, Mario J.

doi:10.1021/jp010094e

Cited by 86 publications

(99 citation statements)

References 36 publications

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“…present work show rough surfaces that may be consistent with the ammonium sulfate microcrystals observed by Zuberi et al (2001) when they found low ice saturation ratios.…”

Section: Mixed-sample Experimentssupporting

confidence: 90%

“…Using this experimental technique we are not able to precisely quantify how small surfaces defects may influence our results. However, work by Zuberi et al (2001) suggests that heterogeneous freezing temperatures in the immersion freezing mode are strongly dependent on surface morphology, specifically surface area and particle microstructure. Optical images of the solid ammonium sulfate particles used in the 8 F08 Fig.…”

Section: Mixed-sample Experimentsmentioning

confidence: 99%

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Depositional ice nucleation on solid ammonium sulfate and glutaric acid particles

2010

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Abstract. Heterogeneous ice nucleation on solid ammonium sulfate and glutaric acid particles was studied using optical microscopy and Raman spectroscopy. Optical microscopy was used to detect selective nucleation events as water vapor was slowly introduced into an environmental sample cell. Particles that nucleated ice were dried via sublimation and examined in detail using Raman spectroscopy. Depositional ice nucleation is highly selective and occurred preferentially on just a few ammonium sulfate and glutaric acid particles in each sample. For freezing temperatures between 214 K and 235 K an average ice saturation ratio of S = 1.10±0.07 for solid ammonium sulfate was observed. Over the same temperature range, S values observed for ice nucleation on glutaric acid particles increased from 1.2 at 235 K to 1.6 at 218 K. Experiments with externally mixed particles further show that ammonium sulfate is a more potent ice nucleus than glutaric acid. Our results suggest that heterogeneous nucleation on ammonium sulfate may be an important pathway for atmospheric ice nucleation and cirrus cloud formation when solid ammonium sulfate aerosol particles are available for ice formation. This pathway for ice formation may be particularly significant near the tropical tropopause region where sulfates are abundant and other species known to be good ice nuclei are depleted.

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“…present work show rough surfaces that may be consistent with the ammonium sulfate microcrystals observed by Zuberi et al (2001) when they found low ice saturation ratios.…”

Section: Mixed-sample Experimentssupporting

confidence: 90%

Section: Mixed-sample Experimentsmentioning

confidence: 99%

Depositional ice nucleation on solid ammonium sulfate and glutaric acid particles

2010

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“…Small embryos of ice might then survive in suited cavities or crevices at the particle surface even at relative humidities substantially below S ice = 1 and cause a lower threshold relative humidity for ice formation in a succeeding nucleation experiment. As an alternative interpretation, the ice crystals may imprint their structure on the surface of soft materials, yielding a surface structure that more closely resembles the ice lattice and that can then act as an activated site to promote ice nucleation (Vali, 2008;Zuberi et al, 2001). A pre-activation has also been observed for particles cooled to temperatures below 236 K and exposed to an environment with S ice <1 in order to explicitly avoid initial ice formation (Fukuta, 1966;Higuchi and Fukuta, 1966).…”

Section: Ice Nucleation Ability Of Sodium Oxalate Crystallisation Atmentioning

confidence: 99%

“…The impact of surface microstructure of crystalline solids on their heterogeneous freezing ability is well documented in the literature, as for example in the case of ammonium sulphate particles. Zuberi et al (2001) have demonstrated that the thermal history of solid ammonium sulphate cores imbedded in aqueous particles affected their morphology and heterogeneous ice nucleability. A crystalline core composed of many microcrystals, Infrared extinction spectra recorded from t = 85 s (spectrum a) to t = 125 s (spectrum e) at a 10 s time interval during expansion run 1 from Exp.…”

Section: Ice Nucleation Ability Of Oxalic Acid Dihydrate Crystallisamentioning

confidence: 99%

High variability of the heterogeneous ice nucleation potential of oxalic acid dihydrate and sodium oxalate

et al. 2010

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Abstract. The heterogeneous ice nucleation potential of airborne oxalic acid dihydrate and sodium oxalate particles in the deposition and condensation mode has been investigated by controlled expansion cooling cycles in the AIDA aerosol and cloud chamber of the Karlsruhe Institute of Technology at temperatures between 244 and 228 K. Previous laboratory studies have highlighted the particular role of oxalic acid dihydrate as the only species amongst a variety of other investigated dicarboxylic acids to be capable of acting as a heterogeneous ice nucleus in both the deposition and immersion mode. We could confirm a high deposition mode ice activity for 0.03 to 0.8 µm sized oxalic acid dihydrate particles that were either formed by nucleation from a gaseous oxalic acid/air mixture or by rapid crystallisation of highly supersaturated aqueous oxalic acid solution droplets. The critical saturation ratio with respect to ice required for deposition nucleation was found to be less than 1.1 and the size-dependent ice-active fraction of the aerosol population was in the range from 0.1 to 22%. In contrast, oxalic acid dihydrate particles that had crystallised from less supersaturated solution droplets and had been allowed to slowly grow in a supersaturated environment from still unfrozen oxalic acid solution droplets over a time period of several hours were found to be much poorer heterogeneous ice nuclei. We speculate that under these conditions a crystal surface structure with less-active sites for the initiation of ice nucleation was generated. Such particles partially proved to be almost ice-inactive in both the deposition and condensation mode. At times, the heterogeneous ice nucleation ability of oxalic acid dihydrate significantly changed when the particles had been processed in preceding cloud droplet activation steps. Such behaviour was also observed for the second investiCorrespondence to: R. Wagner (robert.wagner2@kit.edu) gated species, namely sodium oxalate. Our experiments address the atmospheric scenario that coating layers of oxalic acid or its salts may be formed by physical and chemical processing on pre-existing particulates such as mineral dust and soot. Given the broad diversity of the observed heterogeneous ice nucleability of the oxalate species, it is not straightforward to predict whether an oxalate coating layer will improve or reduce the ice nucleation ability of the seed aerosol particles.

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“…The physical state of aerosol particles is also important for their ability to act as cloud condensation nuclei (CCNs) and has been discussed in the context of cirrus cloud formation (Martin, 1998;Bertram et al, 2000;Zuberi et al, 2001). Although the ice nucleation process largely determines the microphysical properties of cirrus clouds and therefore their climate forcing potential (DeMott et al, 2001), the exact role of aerosol particles in cirrus formation remains unclear (Martin, 2000).…”

Section: Introductionmentioning

confidence: 99%

A novel model to predict the physical state of atmospheric H2SO4/NH3/H2O aerosol particles

et al. 2003

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Abstract. The physical state of the tropospheric aerosol is largely unknown despite its importance for cloud formation and for the aerosol's radiative properties. Here we use detailed microphysical laboratory measurements to perform a systematic global modelling study of the physical state of the H 2 SO 4 /NH 3 /H 2 O aerosol, which constitutes an important class of aerosols in the free troposphere. The Aerosol Physical State Model (APSM) developed here is based on Lagrangian trajectories computed from ECMWF (European Centre for Medium Range Weather Forecasts) analyses, taking full account of the deliquescence/efflorescence hysteresis. As input APSM requires three data sets: (i) deliquescence and efflorescence relative humidities from laboratory measurements, (ii) ammonia-to-sulfate ratios (ASR) calculated by a global circulation model, and (iii) relative humidities determined from the ECMWF analyses. APSM results indicate that globally averaged a significant fraction (17-57%) of the ammoniated sulfate aerosol particles contain solids with the ratio of solid-containing to purely liquid particles increasing with altitude (between 2 and 10 km). In our calculations the most abundant solid is letovicite, (NH 4 ) 3 H(SO 4 ) 2 , while there is only little ammonium sulfate, (NH 4 ) 2 SO 4 . Since ammonium bisulfate, NH 4 HSO 4 , does not nucleate homogeneously, it can only form via heterogeneous crystallization. As the ammonia-to-sulfate ratios of the atmospheric H 2 SO 4 /NH 3 /H 2 O aerosol usually do not correspond to the stoichiometries of known crystalline substances, all solids are expected to occur in mixed-phase aerosol particles. This work highlights the potential importance of letovicite, whose role as cloud condensation nucleus (CCN) and as scatterer of solar radiation remains to be scrutinized.

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Heterogeneous Freezing of Aqueous Particles Induced by Crystallized (NH₄)₂SO₄, Ice, and Letovicite

Cited by 86 publications

References 36 publications

Depositional ice nucleation on solid ammonium sulfate and glutaric acid particles

Depositional ice nucleation on solid ammonium sulfate and glutaric acid particles

High variability of the heterogeneous ice nucleation potential of oxalic acid dihydrate and sodium oxalate

A novel model to predict the physical state of atmospheric H<sub>2</sub>SO<sub>4</sub>/NH<sub>3</sub>/H<sub>2</sub>O aerosol particles

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Heterogeneous Freezing of Aqueous Particles Induced by Crystallized (NH4)2SO4, Ice, and Letovicite

Cited by 86 publications

References 36 publications

Depositional ice nucleation on solid ammonium sulfate and glutaric acid particles

Depositional ice nucleation on solid ammonium sulfate and glutaric acid particles

High variability of the heterogeneous ice nucleation potential of oxalic acid dihydrate and sodium oxalate

A novel model to predict the physical state of atmospheric H&lt;sub&gt;2&lt;/sub&gt;SO&lt;sub&gt;4&lt;/sub&gt;/NH&lt;sub&gt;3&lt;/sub&gt;/H&lt;sub&gt;2&lt;/sub&gt;O aerosol particles

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Heterogeneous Freezing of Aqueous Particles Induced by Crystallized (NH₄)₂SO₄, Ice, and Letovicite

A novel model to predict the physical state of atmospheric H<sub>2</sub>SO<sub>4</sub>/NH<sub>3</sub>/H<sub>2</sub>O aerosol particles