The Ice Selective Inlet: a novel technique for exclusive extraction of pristine ice crystals in mixed-phase clouds

Kupiszewski, Piotr; Weingärtner, E.; Vochezer, Paul; Schnaiter, M.; Bigi, Alessandro; Gysel, M.; Rosati, Bernadette; Toprak, E.; Mertes, Stephan; Baltensperger, Urs

doi:10.5194/amt-8-3087-2015

Cited by 22 publications

(25 citation statements)

References 58 publications

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“…One reason it can be misleading to equate ice residuals with INPs is that MPCgenerated ice crystals can contain cloud condensation nuclei (CCN) which have been collected upon riming but have not acted as INPs. One possibility of overcoming this issue is to sample ice residuals of freshly formed, small ice crystals (< 20 µm), which are assumed to have grown by the initial phase of vapour diffusional growth only (Mertes et al, 2007;Kupiszewski et al, 2015). On mountaintop stations, where such crystals can be collected in-cloud, however, hoar frost (cloud droplets frozen onto surfaces) can be a strong source of small (i.e.…”

Section: Introductionmentioning

confidence: 99%

New type of evidence for secondary ice formation at around −15 °C in mixed-phase clouds

et al. 2019

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Ice crystal numbers can exceed the numbers of icenucleating particles (INPs) observed in mixed-phase clouds (MPCs) by several orders of magnitude, also at temperatures that are colder than − 8 • C. This disparity provides circumstantial evidence of secondary ice formation, also other than via the Hallett-Mossop process. In a new approach, we made use of the fact that planar, branched ice crystals (e.g. dendrites) grow within a relatively narrow temperature range (i.e. −12 to −17 • C) and can be analysed individually for INPs using a field-deployable drop-freezing assay. The novelty of our approach lies in comparing the growth temperature encoded in the habit of an individual crystal with the activation temperature of the most efficient INP contained within the same crystal to tell whether it may be the result of primary ice formation. In February and March 2018, we analysed a total of 190 dendritic crystals (∼ 3 mm median size) deposited within MPCs at the high-altitude research station Jungfraujoch (3580 m a.s.l.). Overall, one in eight of the analysed crystals contained an INP active at −17 • C or warmer, while the remaining seven most likely resulted from secondary ice formation within the clouds. The ice multiplication factor we observed was small (8), but relatively stable throughout the course of documentation. These measurements show that secondary ice can be observed at temperatures around −15 • C and thus advance our understanding of the extent of secondary ice formation in MPCs, even where the multiplication factor is smaller than 10.

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Section: Introductionmentioning

confidence: 99%

New type of evidence for secondary ice formation at around −15 °C in mixed-phase clouds

et al. 2019

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“…Following field measurements at the Jungfraujoch, Cozic et al [2008] and Mertes et al [2007] reported enrichment by mass of BC in IR based on particle soot absorption photometer (PSAP) measurements, while Ebert et al [2011] found enrichment by number of C-O-S particles (i.e., internal mixtures of organics, nitrates, and sulfates, sometimes containing soot inclusions) in IR relative to the interstitial aerosol using scanning electron microscopy and transmission This paper focuses on measurements of the physical properties and BC content of IR sampled using the Ice-CVI during the joint CLACE 2013 and Ice Nuclei Research Unit (INUIT) campaign. The campaign was conducted at the high-alpine research station Jungfraujoch in the winter of 2013 with the principal goals of investigating the characteristics of INP [Boose et al, 2016;Kupiszewski et al, 2015;Worringen et al, 2015] and cloud microphysical properties [Lloyd et al, 2015;Vochezer et al, 2016]. Based on an analysis of IR size distributions measured downstream of the Ice-CVI, the size of particles predominantly acting as INP in MPCs is determined.…”

Section: Introductionmentioning

confidence: 99%

Ice residual properties in mixed‐phase clouds at the high‐alpine Jungfraujoch site

et al. 2016

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Ice residual (IR) and total aerosol properties were measured in mixed‐phase clouds (MPCs) at the high‐alpine Jungfraujoch research station. Black carbon (BC) content and coating thickness of BC‐containing particles were determined using single‐particle soot photometers. The ice activated fraction (IAF), derived from a comparison of IR and total aerosol particle size distributions, showed an enrichment of large particles in the IR, with an increase in the IAF from values on the order of 10−4 to 10−3 for 100 nm (diameter) particles to 0.2 to 0.3 for 1 μm (diameter) particles. Nonetheless, due to the high number fraction of submicrometer particles with respect to total particle number, IR size distributions were still dominated by the submicrometer aerosol. A comparison of simultaneously measured number size distributions of BC‐free and BC‐containing IR and total aerosol particles showed depletion of BC by number in the IR, suggesting that BC does not play a significant role in ice nucleation in MPCs at the Jungfraujoch. The potential anthropogenic climate impact of BC via the glaciation effect in MPCs is therefore likely to be negligible at this site and in environments with similar meteorological conditions and a similar aerosol population. The IAF of the BC‐containing particles also increased with total particle size, in a similar manner as for the BC‐free particles, but on a level 1 order of magnitude lower. Furthermore, BC‐containing IR were found to have a thicker coating than the BC‐containing total aerosol, suggesting the importance of atmospheric aging for ice nucleation.

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“…At present, these effects are difficult to parameterize in models due to a lack of observational research on formation, properties, and phase partitioning (Kamphus et al, 2010;Shupe et al, 2006). This has resulted in a global effort to study these clouds (Abel et al, 2014;Davis et al, 2007a;Hiranuma et al, 2016a;Kupiszewski et al, 2015;Mertes et al, 2007;Patade et al, 2015).…”

Section: Introductionmentioning

confidence: 99%

A Phase Separation Inlet for Droplets, Ice Residuals, and Interstitial Aerosols

Koolik

Roesch

Deloya

et al. 2020

Preprint

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Abstract. A new inlet for studying the aerosols and hydrometeor residuals that compose mixed-phase clouds – the phaSe seParation Inlet for Droplets icE residuals and inteRstitial aerosols (SPIDER) – is described here. SPIDER combines an omni-directional inlet, a Large-Pumped Counterflow Virtual Impactor (L-PCVI), a flow tube evaporation chamber, and a Pumped Counterflow Virtual Impactor (PCVI) to separate droplets, ice crystals, and interstitial aerosols for simultaneous sampling. Laboratory verification tests of each individual component and the composite SPIDER system were conducted. SPIDER was deployed to Storm Peak Laboratory (SPL), a mountain-top research facility at 3210 m a.s.l. in the Rocky Mountains, for a three-week field campaign. SPIDER performance as a field instrument is presented with data that demonstrates its capability of separating distinct cloud elements and interstitial aerosol. Possible design improvements of SPIDER are also suggested.

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The Ice Selective Inlet: a novel technique for exclusive extraction of pristine ice crystals in mixed-phase clouds

Abstract: Abstract. Climate predictions are affected by high uncertainties partially due to an insufficient knowledge of aerosolcloud interactions.

Cited by 22 publications

References 58 publications

New type of evidence for secondary ice formation at around −15 °C in mixed-phase clouds

New type of evidence for secondary ice formation at around −15 °C in mixed-phase clouds

Ice residual properties in mixed‐phase clouds at the high‐alpine Jungfraujoch site

A Phase Separation Inlet for Droplets, Ice Residuals, and Interstitial Aerosols

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