Articles | Volume 15, issue 18
https://doi.org/10.5194/amt-15-5367-2022
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/amt-15-5367-2022
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Research article
| 
21 Sep 2022
Research article |
| 21 Sep 2022
| 21 Sep 2022
The Microfluidic Ice Nuclei Counter Zürich (MINCZ): a platform for homogeneous and heterogeneous ice nucleation
Florin N. Isenrich
Institute for Chemical and Bioengineering, ETH Zurich, Zürich,
8093, Switzerland
Institute for Atmospheric and Climate Science, ETH Zurich, Zürich, 8092, Switzerland
Michael Rösch
Institute for Atmospheric and Climate Science, ETH Zurich, Zürich, 8092, Switzerland
Julia Nette
Institute for Chemical and Bioengineering, ETH Zurich, Zürich,
8093, Switzerland
Stavros Stavrakis
Institute for Chemical and Bioengineering, ETH Zurich, Zürich,
8093, Switzerland
Claudia Marcolli
Institute for Atmospheric and Climate Science, ETH Zurich, Zürich, 8092, Switzerland
Zamin A. Kanji
Institute for Atmospheric and Climate Science, ETH Zurich, Zürich, 8092, Switzerland
Andrew J. deMello
CORRESPONDING AUTHOR
Institute for Chemical and Bioengineering, ETH Zurich, Zürich,
8093, Switzerland
Ulrike Lohmann
Institute for Atmospheric and Climate Science, ETH Zurich, Zürich, 8092, Switzerland
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Yichen Jia, Hendrik Andersen, David Neubauer, Ulrike Lohmann, Corinna Hoose, and Jan Cermak
EGUsphere, https://doi.org/10.5194/egusphere-2026-569, https://doi.org/10.5194/egusphere-2026-569, 2026
This preprint is open for discussion and under review for Atmospheric Chemistry and Physics (ACP).
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Understanding how ocean clouds respond to air pollution is important for climate projections. Using artificial intelligence and a climate model, we show that some model settings produce very high cloud cover, leaving little room for further cloud growth as pollution increases. This “headroom effect” can make cloud responses appear weak. Our results highlight the need to consider existing cloud conditions when interpreting how cloud cover responds to the environment.
Jie Chen and Zamin A. Kanji
EGUsphere, https://doi.org/10.5194/egusphere-2025-6368, https://doi.org/10.5194/egusphere-2025-6368, 2026
This preprint is open for discussion and under review for Atmospheric Chemistry and Physics (ACP).
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Desert dust particles act as important seeds that enable cloud droplets to freeze. However, their ice formation ability is highly variable and difficult to represent in climate models. By analyzing previously published data, we found that both the measurement methods used and the way dust ages strongly influence its ice forming behavior. We developed new parameterizations that account for these effects, which are expected to improve the prediction of how dust impacts cloud formation and climate.
Huiying Zhang, Chia Rui Ong, Anurag Dipankar, Ulrike Lohmann, and Jan Henneberger
EGUsphere, https://doi.org/10.5194/egusphere-2026-470, https://doi.org/10.5194/egusphere-2026-470, 2026
This preprint is open for discussion and under review for Atmospheric Chemistry and Physics (ACP).
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We used computer simulations to study cloud seeding. We discovered a 'self-lofting' mechanism whereby, as the seeded ice crystals grow, they release heat, generating an upward air current. This enables the ice plume to rise and spread vertically, even when the surrounding air is sinking. This is why seeded ice survives in unfavourable wind conditions. Our results demonstrate that this internal heating is essential for the effectiveness and validation of weather modification technologies.
Yu Wang, Beiping Luo, Judith Kleinheins, Gang I. Chen, Liine Heikkinen, and Claudia Marcolli
Atmos. Chem. Phys., 26, 1735–1749, https://doi.org/10.5194/acp-26-1735-2026, https://doi.org/10.5194/acp-26-1735-2026, 2026
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Ubiquitous semi-volatile compounds can co-condense on aerosol particles with water vapour when relative humidity increases. Simulations of cloud formation at a boreal forest site with a cloud parcel model that accounts for non-ideal organic–inorganic interactions yield an enhancement of cloud droplet number concentration from co-condensing NH3, HNO3, and organics up to 44%, with strong sensitivities to volatility distributions, aerosol size distribution, and updraft velocity.
Andrina Caratsch, Sylvaine Ferrachat, and Ulrike Lohmann
EGUsphere, https://doi.org/10.5194/egusphere-2025-6186, https://doi.org/10.5194/egusphere-2025-6186, 2026
This preprint is open for discussion and under review for Geoscientific Model Development (GMD).
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Tropical cyclones come in various size and shape, which smoothes out key storm features in composite analyses. To address this, we developed a compositing method that symmetrizes storms and better aligns their eyewalls and horizontal extents prior to compositing. This approach preserves small-scale features in the composites, reduces within-group variance, and enhances the power of statistical testing. The method facilitates the investigation and understanding of tropical cyclone development.
Huiying Zhang, Fabiola Ramelli, Christopher Fuchs, Nadja Omanovic, Anna J. Miller, Robert Spirig, Zhaolong Wu, Yunpei Chu, Xia Li, Ulrike Lohmann, and Jan Henneberger
Atmos. Chem. Phys., 26, 1459–1481, https://doi.org/10.5194/acp-26-1459-2026, https://doi.org/10.5194/acp-26-1459-2026, 2026
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Ice crystals in clouds aggregate, shaping snow and rain, yet rates are hard to measure. Using cloud seeding, we sampled crystals downwind after known times. A deep-learning algorithm quantified aggregation by counting crystal components. Initial ice concentration was the main driver, confirmed by causal analysis, physics, and machine learning, though weaker than theory predicts. Temperature, size, and shape also mattered, while turbulence was negligible.
Marilena Gidarakou, Alexandros Papayannis, Kunfeng Gao, Panagiotis Gidarakos, Benoît Crouzy, Romanos Foskinis, Sophie Erb, Benjamin T. Brem, Cuiqi Zhang, Gian Lieberherr, Martine Collaud Coen, Branko Sikoparija, Zamin A. Kanji, Bernard Clot, Bertrand Calpini, Eugenia Giagka, and Athanasios Nenes
Atmos. Chem. Phys., 26, 923–945, https://doi.org/10.5194/acp-26-923-2026, https://doi.org/10.5194/acp-26-923-2026, 2026
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Vertical profiles of pollen and biomass burning particles were obtained at a semi-rural site at the MeteoSwiss station near Payerne (Switzerland) using a novel multi-channel elastic-fluorescence lidar system combined with in situ measurements during the spring 2023 wildfires and pollination season during the PERICLES (PayernE lidaR and Insitu detection of fluorescent bioaerosol and dust partiCLES and their cloud impacts) campaign.
Nikolaos Papaevangelou, Diego Villanueva, and Ulrike Lohmann
EGUsphere, https://doi.org/10.5194/egusphere-2025-6348, https://doi.org/10.5194/egusphere-2025-6348, 2026
This preprint is open for discussion and under review for Atmospheric Chemistry and Physics (ACP).
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Hailstorms cause significant damage worldwide, and cloud seeding with ice-nucleating particles is used as a hail mitigation measure, including in Switzerland. In this study, we investigate the impact of silver iodide perturbations on eight convective storms over Switzerland and southern Germany using the COSMO model. The results show that, in most cases, mean hail size increases after seeding, while the hail-affected area decreases in the majority of simulations.
Nadja Omanovic, Debora Bötticher, Christopher Fuchs, and Ulrike Lohmann
EGUsphere, https://doi.org/10.5194/egusphere-2025-5916, https://doi.org/10.5194/egusphere-2025-5916, 2025
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The interplay of liquid and ice particles in clouds is a crucial driver for forming rain over land. We use numerical simulations to evaluate how fast clouds can be glaciated through ice particles and how this depends on different initial states of the cloud. We find that the more water a cloud contains, the longer the glaciation takes while any additional turbulent mixing does not have a major impact.
Mattia Righi, Baptiste Testa, Christof G. Beer, Johannes Hendricks, and Zamin A. Kanji
Atmos. Chem. Phys., 25, 18341–18353, https://doi.org/10.5194/acp-25-18341-2025, https://doi.org/10.5194/acp-25-18341-2025, 2025
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The effective radiative forcing due to the effect of aviation soot on natural cirrus clouds is likely very small, thus confirming most previous studies, but for the first time with the support of laboratory measurements specifically targeting aviation soot and its ice nucleation ability.
Nadia Shardt, Florin N. Isenrich, Julia Nette, Christopher Dreimol, Ning Ma, Zamin A. Kanji, Andrew J. deMello, and Claudia Marcolli
Atmos. Chem. Phys., 25, 17997–18014, https://doi.org/10.5194/acp-25-17997-2025, https://doi.org/10.5194/acp-25-17997-2025, 2025
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In the atmosphere, minerals suspended in cloud droplets promote the formation of ice. We investigated ice formation in the presence of pure and binary mixtures of common minerals using a microfluidic device. The mineral with the best ability to initiate ice formation alone (that is, at the highest temperature) typically determined when ice formed in the binary mixture.
Mayur G. Sapkal, Michael Rösch, and Zamin A. Kanji
Atmos. Meas. Tech., 18, 5649–5667, https://doi.org/10.5194/amt-18-5649-2025, https://doi.org/10.5194/amt-18-5649-2025, 2025
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The newly developed Horizontal Cloud Condensation Nuclei Counter (HCCNC) is capable of generating supersaturation as low as 0.05 % at temperatures as low as 4 °C, allowing for the investigation of CCN activity of ammonium sulfate particles up to 200 nm diameter and ambient aerosol of larger diameter. The HCCNC could be used for low-temperature experiments where gas-phase partitioning into or out of the aerosol phase for semi-volatile compounds is relevant for CCN activity.
Christopher Fuchs, Fabiola Ramelli, Anna J. Miller, Nadja Omanovic, Robert Spirig, Huiying Zhang, Patric Seifert, Kevin Ohneiser, Ulrike Lohmann, and Jan Henneberger
Atmos. Chem. Phys., 25, 12177–12196, https://doi.org/10.5194/acp-25-12177-2025, https://doi.org/10.5194/acp-25-12177-2025, 2025
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We quantify diffusional ice crystal growth in natural clouds using cloud seeding experiments. We report growth rates for 14 experiments between −5.1 °C and −8.3 °C and observe strong variations depending on the cloud characteristics. Comparing our growth rates to laboratory data, we found similar temperature-dependent trends, but the laboratory rates are higher. These data fill the gap in quantitative in situ observation of ice crystal growth, helping to validate models and laboratory experiments.
Luis A. Ladino, Karin Ardon-Dryer, Diana L. Pereira, Ulrike Proske, Zyanya Ramirez-Diaz, Antonia Velicu, and Zamin A. Kanji
EGUsphere, https://doi.org/10.5194/egusphere-2025-4499, https://doi.org/10.5194/egusphere-2025-4499, 2025
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A survey and literature metadata analysis from the cloud physics community are used to investigate the state of diversity, equity and inclusion in the cloud physics research community. We show the evolution of gender contributions to cloud physics and the inclusion of scientists from the Global South. The publication analysis reveals the rate of men and women dropping out of the field is not different, however, gender balance was better achieved when women led publications compared to men.
Kai Jeggle, David Neubauer, Hanin Binder, and Ulrike Lohmann
Atmos. Chem. Phys., 25, 7227–7243, https://doi.org/10.5194/acp-25-7227-2025, https://doi.org/10.5194/acp-25-7227-2025, 2025
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This work uncovers the formation regimes of cirrus clouds and how dust particles influence their properties. By applying machine learning to a combination of satellite and reanalysis data, cirrus clouds are classified into different formation regimes. Depending on the regime, increasing dust aerosol concentrations can either decrease or increase the number of ice crystals. This challenges the idea of using cloud seeding to cool the planet, as it may unintentionally lead to warming instead.
Christopher Fuchs, Fabiola Ramelli, David Schweizer, Ulrike Lohmann, and Jan Henneberger
Atmos. Meas. Tech., 18, 2969–2986, https://doi.org/10.5194/amt-18-2969-2025, https://doi.org/10.5194/amt-18-2969-2025, 2025
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We present a new instrument based on digital in-line holography (SmHOLIMO) for in situ cloud measurements. SmHOLIMO is designed to specifically measure small cloud droplets with diameters > 3.7 μm. This way we retrieve accurate cloud droplet size distributions, which are crucial to understand the evolution and governing microphysical processes of a cloud. Results of a field study are compared to co-located measurements of a second holographic imager, microwave radiometer, and cloud radar.
Guangyu Li, André Welti, Iris Thurnherr, Ulrike Lohmann, and Zamin A. Kanji
EGUsphere, https://doi.org/10.5194/egusphere-2025-2798, https://doi.org/10.5194/egusphere-2025-2798, 2025
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This study presents ship-based measurements of summertime ice-nucleating particles (INPs) over the data-scarce Eurasian-Arctic Seas. We found that INPs are driven by both local and regional sources, with the highest levels observed near land and over ice-free waters. This study is highlighted for improving the understanding of INP abundance, sources, and their role in cloud processes in the rapidly warming Arctic.
Anna J. Miller, Christopher Fuchs, Fabiola Ramelli, Huiying Zhang, Nadja Omanovic, Robert Spirig, Claudia Marcolli, Zamin A. Kanji, Ulrike Lohmann, and Jan Henneberger
Atmos. Chem. Phys., 25, 5387–5407, https://doi.org/10.5194/acp-25-5387-2025, https://doi.org/10.5194/acp-25-5387-2025, 2025
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We analyzed the ability of silver iodide particles (a commonly used cloud-seeding agent) to form ice crystals in naturally occurring liquid clouds at −5 to −8 °C and found that only ≈ 0.1 %−1 % of particles nucleate ice, with a negative dependence on temperature. By contextualizing our results with previous laboratory studies, we help to bridge the gap between laboratory and field experiments, which also helps to inform future cloud-seeding projects.
Judith Kleinheins, Nadia Shardt, Ulrike Lohmann, and Claudia Marcolli
Atmos. Chem. Phys., 25, 881–903, https://doi.org/10.5194/acp-25-881-2025, https://doi.org/10.5194/acp-25-881-2025, 2025
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We model the cloud condensation nuclei (CCN) activation of sea spray aerosol particles with classical Köhler theory and with a new model approach that takes surface tension lowering into account. We categorize organic compounds into weak, intermediate, and strong surfactants, and we outline for which composition surface tension lowering is important. The results suggest that surface tension lowering allows sea spray aerosol particles in the Aitken mode to be a source of CCN in marine updraughts.
Nadja Omanovic, Brigitta Goger, and Ulrike Lohmann
Atmos. Chem. Phys., 24, 14145–14175, https://doi.org/10.5194/acp-24-14145-2024, https://doi.org/10.5194/acp-24-14145-2024, 2024
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We evaluated the numerical weather model ICON in two horizontal resolutions with two bulk microphysics schemes over hilly and complex terrain in Switzerland and Austria, respectively. We focused on the model's ability to simulate mid-level clouds in summer and winter. By combining observational data from two different field campaigns, we show that an increase in the horizontal resolution and a more advanced cloud microphysics scheme is strongly beneficial for cloud representation.
Baptiste Testa, Lukas Durdina, Jacinta Edebeli, Curdin Spirig, and Zamin A. Kanji
Atmos. Chem. Phys., 24, 10409–10424, https://doi.org/10.5194/acp-24-10409-2024, https://doi.org/10.5194/acp-24-10409-2024, 2024
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Aviation soot residuals released from contrails can become compacted upon sublimation of the ice crystals, generating new voids in the aggregates where ice nucleation can occur. Here we show that contrail-processed soot is highly compact but that it remains unable to form ice at a relative humidity different from that required for the formation of background cirrus from the more ubiquitous aqueous solution droplets, suggesting that it will not perturb cirrus cloud formation via ice nucleation.
Emilie Fons, Ann Kristin Naumann, David Neubauer, Theresa Lang, and Ulrike Lohmann
Atmos. Chem. Phys., 24, 8653–8675, https://doi.org/10.5194/acp-24-8653-2024, https://doi.org/10.5194/acp-24-8653-2024, 2024
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Aerosols can modify the liquid water path (LWP) of stratocumulus and, thus, their radiative effect. We compare storm-resolving model and satellite data that disagree on the sign of LWP adjustments and diagnose this discrepancy with causal inference. We find that strong precipitation, the absence of wet scavenging, and cloud deepening under a weak inversion contribute to positive LWP adjustments to aerosols in the model, despite weak negative effects from cloud-top entrainment enhancement.
Nadja Omanovic, Sylvaine Ferrachat, Christopher Fuchs, Jan Henneberger, Anna J. Miller, Kevin Ohneiser, Fabiola Ramelli, Patric Seifert, Robert Spirig, Huiying Zhang, and Ulrike Lohmann
Atmos. Chem. Phys., 24, 6825–6844, https://doi.org/10.5194/acp-24-6825-2024, https://doi.org/10.5194/acp-24-6825-2024, 2024
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We present simulations with a high-resolution numerical weather prediction model to study the growth of ice crystals in low clouds following glaciogenic seeding. We show that the simulated ice crystals grow slower than observed and do not consume as many cloud droplets as measured in the field. This may have implications for forecasting precipitation, as the ice phase is crucial for precipitation at middle and high latitudes.
Ulrike Proske, Sylvaine Ferrachat, and Ulrike Lohmann
Atmos. Chem. Phys., 24, 5907–5933, https://doi.org/10.5194/acp-24-5907-2024, https://doi.org/10.5194/acp-24-5907-2024, 2024
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Climate models include treatment of aerosol particles because these influence clouds and radiation. Over time their representation has grown increasingly detailed. This complexity may hinder our understanding of model behaviour. Thus here we simplify the aerosol representation of our climate model by prescribing mean concentrations, which saves run time and helps to discover unexpected model behaviour. We conclude that simplifications provide a new perspective for model study and development.
Zane Dedekind, Ulrike Proske, Sylvaine Ferrachat, Ulrike Lohmann, and David Neubauer
Atmos. Chem. Phys., 24, 5389–5404, https://doi.org/10.5194/acp-24-5389-2024, https://doi.org/10.5194/acp-24-5389-2024, 2024
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Ice particles precipitating into lower clouds from an upper cloud, the seeder–feeder process, can enhance precipitation. A numerical modeling study conducted in the Swiss Alps found that 48 % of observed clouds were overlapping, with the seeder–feeder process occurring in 10 % of these clouds. Inhibiting the seeder–feeder process reduced the surface precipitation and ice particle growth rates, which were further reduced when additional ice multiplication processes were included in the model.
Baptiste Testa, Lukas Durdina, Peter A. Alpert, Fabian Mahrt, Christopher H. Dreimol, Jacinta Edebeli, Curdin Spirig, Zachary C. J. Decker, Julien Anet, and Zamin A. Kanji
Atmos. Chem. Phys., 24, 4537–4567, https://doi.org/10.5194/acp-24-4537-2024, https://doi.org/10.5194/acp-24-4537-2024, 2024
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Laboratory experiments on the ice nucleation of real commercial aviation soot particles are investigated for their cirrus cloud formation potential. Our results show that aircraft-emitted soot in the upper troposphere will be poor ice-nucleating particles. Measuring the soot particle morphology and modifying their mixing state allow us to elucidate why these particles are ineffective at forming ice, in contrast to previously used soot surrogates.
Anna J. Miller, Fabiola Ramelli, Christopher Fuchs, Nadja Omanovic, Robert Spirig, Huiying Zhang, Ulrike Lohmann, Zamin A. Kanji, and Jan Henneberger
Atmos. Meas. Tech., 17, 601–625, https://doi.org/10.5194/amt-17-601-2024, https://doi.org/10.5194/amt-17-601-2024, 2024
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We present a method for aerosol and cloud research using two uncrewed aerial vehicles (UAVs). The UAVs have a propeller heating mechanism that allows flights in icing conditions, which has so far been a limitation for cloud research with UAVs. One UAV burns seeding flares, producing a plume of particles that causes ice formation in supercooled clouds. The second UAV measures aerosol size distributions and is used for measuring the seeding plume or for characterizing the boundary layer.
Guangyu Li, Elise K. Wilbourn, Zezhen Cheng, Jörg Wieder, Allison Fagerson, Jan Henneberger, Ghislain Motos, Rita Traversi, Sarah D. Brooks, Mauro Mazzola, Swarup China, Athanasios Nenes, Ulrike Lohmann, Naruki Hiranuma, and Zamin A. Kanji
Atmos. Chem. Phys., 23, 10489–10516, https://doi.org/10.5194/acp-23-10489-2023, https://doi.org/10.5194/acp-23-10489-2023, 2023
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In this work, we present results from an Arctic field campaign (NASCENT) in Ny-Ålesund, Svalbard, on the abundance, variability, physicochemical properties, and potential sources of ice-nucleating particles (INPs) relevant for mixed-phase cloud formation. This work improves the data coverage of Arctic INPs and aerosol properties, allowing for the validation of models predicting cloud microphysical and radiative properties of mixed-phase clouds in the rapidly warming Arctic.
Bernhard M. Enz, Jan P. Engelmann, and Ulrike Lohmann
Geosci. Model Dev., 16, 5093–5112, https://doi.org/10.5194/gmd-16-5093-2023, https://doi.org/10.5194/gmd-16-5093-2023, 2023
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An algorithm to track tropical cyclones in model simulation data has been developed. The algorithm uses many combinations of varying parameter thresholds to detect weaker phases of tropical cyclones while still being resilient to false positives. It is shown that the algorithm performs well and adequately represents the tropical cyclone activity of the underlying simulation data. The impact of false positives on overall tropical cyclone activity is shown to be insignificant.
Dimitri Castarède, Zoé Brasseur, Yusheng Wu, Zamin A. Kanji, Markus Hartmann, Lauri Ahonen, Merete Bilde, Markku Kulmala, Tuukka Petäjä, Jan B. C. Pettersson, Berko Sierau, Olaf Stetzer, Frank Stratmann, Birgitta Svenningsson, Erik Swietlicki, Quynh Thu Nguyen, Jonathan Duplissy, and Erik S. Thomson
Atmos. Meas. Tech., 16, 3881–3899, https://doi.org/10.5194/amt-16-3881-2023, https://doi.org/10.5194/amt-16-3881-2023, 2023
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Clouds play a key role in Earth’s climate by influencing the surface energy budget. Certain types of atmospheric aerosols, called ice-nucleating particles (INPs), induce the formation of ice in clouds and, thus, often initiate precipitation formation. The Portable Ice Nucleation Chamber 2 (PINCii) is a new instrument developed to study ice formation and to conduct ambient measurements of INPs, allowing us to investigate the sources and properties of the atmospheric aerosols that can act as INPs.
Colin Tully, David Neubauer, Diego Villanueva, and Ulrike Lohmann
Atmos. Chem. Phys., 23, 7673–7698, https://doi.org/10.5194/acp-23-7673-2023, https://doi.org/10.5194/acp-23-7673-2023, 2023
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This study details the first attempt with a GCM to simulate a fully prognostic aerosol species specifically for cirrus climate intervention. The new approach is in line with the real-world delivery mechanism via aircraft. However, to achieve an appreciable signal from seeding, smaller particles were needed, and their mass emissions needed to be scaled by at least a factor of 100. These biases contributed to either overseeding or small and insignificant effects in response to seeding cirrus.
Colin Tully, David Neubauer, and Ulrike Lohmann
Geosci. Model Dev., 16, 2957–2973, https://doi.org/10.5194/gmd-16-2957-2023, https://doi.org/10.5194/gmd-16-2957-2023, 2023
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A new method to simulate deterministic ice nucleation processes based on the differential activated fraction was evaluated against a cumulative approach. Box model simulations of heterogeneous-only ice nucleation within cirrus suggest that the latter approach likely underpredicts the ice crystal number concentration. Longer simulations with a GCM show that choosing between these two approaches impacts ice nucleation competition within cirrus but leads to small and insignificant climate effects.
Anand Kumar, Kristian Klumpp, Chen Barak, Giora Rytwo, Michael Plötze, Thomas Peter, and Claudia Marcolli
Atmos. Chem. Phys., 23, 4881–4902, https://doi.org/10.5194/acp-23-4881-2023, https://doi.org/10.5194/acp-23-4881-2023, 2023
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Smectites are a major class of clay minerals that are ice nucleation (IN) active. They form platelets that swell or even delaminate in water by intercalation of water between their layers. We hypothesize that at least three smectite layers need to be stacked together to host a critical ice embryo on clay mineral edges and that the larger the surface edge area is, the higher the freezing temperature. Edge sites on such clay particles play a crucial role in imparting IN ability to such particles.
Zane Dedekind, Jacopo Grazioli, Philip H. Austin, and Ulrike Lohmann
Atmos. Chem. Phys., 23, 2345–2364, https://doi.org/10.5194/acp-23-2345-2023, https://doi.org/10.5194/acp-23-2345-2023, 2023
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Simulations allowing ice particles to collide with one another producing more ice particles represented surface observations of ice particles accurately. An increase in ice particles formed through collisions was related to sharp changes in the wind direction and speed with height. Changes in wind speed and direction can therefore cause more enhanced collisions between ice particles and alter how fast and how much precipitation forms. Simulations were conducted with the atmospheric model COSMO.
Adriana Bailey, Franziska Aemisegger, Leonie Villiger, Sebastian A. Los, Gilles Reverdin, Estefanía Quiñones Meléndez, Claudia Acquistapace, Dariusz B. Baranowski, Tobias Böck, Sandrine Bony, Tobias Bordsdorff, Derek Coffman, Simon P. de Szoeke, Christopher J. Diekmann, Marina Dütsch, Benjamin Ertl, Joseph Galewsky, Dean Henze, Przemyslaw Makuch, David Noone, Patricia K. Quinn, Michael Rösch, Andreas Schneider, Matthias Schneider, Sabrina Speich, Bjorn Stevens, and Elizabeth J. Thompson
Earth Syst. Sci. Data, 15, 465–495, https://doi.org/10.5194/essd-15-465-2023, https://doi.org/10.5194/essd-15-465-2023, 2023
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One of the novel ways EUREC4A set out to investigate trade wind clouds and their coupling to the large-scale circulation was through an extensive network of isotopic measurements in water vapor, precipitation, and seawater. Samples were taken from the island of Barbados, from aboard two aircraft, and from aboard four ships. This paper describes the full collection of EUREC4A isotopic in situ data and guides readers to complementary remotely sensed water vapor isotope ratios.
Kristian Klumpp, Claudia Marcolli, Ana Alonso-Hellweg, Christopher H. Dreimol, and Thomas Peter
Atmos. Chem. Phys., 23, 1579–1598, https://doi.org/10.5194/acp-23-1579-2023, https://doi.org/10.5194/acp-23-1579-2023, 2023
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The prerequisites of a particle surface for efficient ice nucleation are still poorly understood. This study compares the ice nucleation activity of two chemically identical but morphologically different minerals (kaolinite and halloysite). We observe, on average, not only higher ice nucleation activities for halloysite than kaolinite but also higher diversity between individual samples. We identify the particle edges as being the most likely site for ice nucleation.
Fabian Mahrt, Carolin Rösch, Kunfeng Gao, Christopher H. Dreimol, Maria A. Zawadowicz, and Zamin A. Kanji
Atmos. Chem. Phys., 23, 1285–1308, https://doi.org/10.5194/acp-23-1285-2023, https://doi.org/10.5194/acp-23-1285-2023, 2023
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Major aerosol types emitted by biomass burning include soot, ash, and charcoal particles. Here, we investigated the ice nucleation activity of 400 nm size-selected particles of two different pyrolyis-derived charcoal types in the mixed phase and cirrus cloud regime. We find that ice nucleation is constrained to cirrus cloud conditions, takes place via pore condensation and freezing, and is largely governed by the particle porosity and mineral content.
Julie Thérèse Pasquier, Jan Henneberger, Fabiola Ramelli, Annika Lauber, Robert Oscar David, Jörg Wieder, Tim Carlsen, Rosa Gierens, Marion Maturilli, and Ulrike Lohmann
Atmos. Chem. Phys., 22, 15579–15601, https://doi.org/10.5194/acp-22-15579-2022, https://doi.org/10.5194/acp-22-15579-2022, 2022
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It is important to understand how ice crystals and cloud droplets form in clouds, as their concentrations and sizes determine the exact radiative properties of the clouds. Normally, ice crystals form from aerosols, but we found evidence for the formation of additional ice crystals from the original ones over a large temperature range within Arctic clouds. In particular, additional ice crystals were formed during collisions of several ice crystals or during the freezing of large cloud droplets.
Nikou Hamzehpour, Claudia Marcolli, Sara Pashai, Kristian Klumpp, and Thomas Peter
Atmos. Chem. Phys., 22, 14905–14930, https://doi.org/10.5194/acp-22-14905-2022, https://doi.org/10.5194/acp-22-14905-2022, 2022
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Playa surfaces in Iran that emerged through Lake Urmia (LU) desiccation have become a relevant dust source of regional relevance. Here, we identify highly erodible LU playa surfaces and determine their physicochemical properties and mineralogical composition and perform emulsion-freezing experiments with them. We find high ice nucleation activities (up to 250 K) that correlate positively with organic matter and clay content and negatively with pH, salinity, K-feldspars, and quartz.
Nikou Hamzehpour, Claudia Marcolli, Kristian Klumpp, Debora Thöny, and Thomas Peter
Atmos. Chem. Phys., 22, 14931–14956, https://doi.org/10.5194/acp-22-14931-2022, https://doi.org/10.5194/acp-22-14931-2022, 2022
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Dust aerosols from dried lakebeds contain mineral particles, as well as soluble salts and (bio-)organic compounds. Here, we investigate ice nucleation (IN) activity of dust samples from Lake Urmia playa, Iran. We find high IN activity of the untreated samples that decreases after organic matter removal but increases after removing soluble salts and carbonates, evidencing inhibiting effects of soluble salts and carbonates on the IN activity of organic matter and minerals, especially microcline.
Guangyu Li, Jörg Wieder, Julie T. Pasquier, Jan Henneberger, and Zamin A. Kanji
Atmos. Chem. Phys., 22, 14441–14454, https://doi.org/10.5194/acp-22-14441-2022, https://doi.org/10.5194/acp-22-14441-2022, 2022
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The concentration of ice-nucleating particles (INPs) is atmospherically relevant for primary ice formation in clouds. In this work, from 12 weeks of field measurement data in the Arctic, we developed a new parameterization to predict INP concentrations applicable for pristine background conditions based only on temperature. The INP parameterization could improve the cloud microphysical representation in climate models, aiding in Arctic climate predictions.
Colin Tully, David Neubauer, Nadja Omanovic, and Ulrike Lohmann
Atmos. Chem. Phys., 22, 11455–11484, https://doi.org/10.5194/acp-22-11455-2022, https://doi.org/10.5194/acp-22-11455-2022, 2022
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The proposed geoengineering method, cirrus cloud thinning, was evaluated using a more physically based microphysics scheme coupled to a more realistic approach for calculating ice cloud fractions in the ECHAM-HAM GCM. Sensitivity tests reveal that using the new ice cloud fraction approach and increasing the critical ice saturation ratio for ice nucleation on seeding particles reduces warming from overseeding. However, this geoengineering method is unlikely to be feasible on a global scale.
Jörg Wieder, Nikola Ihn, Claudia Mignani, Moritz Haarig, Johannes Bühl, Patric Seifert, Ronny Engelmann, Fabiola Ramelli, Zamin A. Kanji, Ulrike Lohmann, and Jan Henneberger
Atmos. Chem. Phys., 22, 9767–9797, https://doi.org/10.5194/acp-22-9767-2022, https://doi.org/10.5194/acp-22-9767-2022, 2022
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Ice formation and its evolution in mixed-phase clouds are still uncertain. We evaluate the lidar retrieval of ice-nucleating particle concentration in dust-dominated and continental air masses over the Swiss Alps with in situ observations. A calibration factor to improve the retrieval from continental air masses is proposed. Ice multiplication factors are obtained with a new method utilizing remote sensing. Our results indicate that secondary ice production occurs at temperatures down to −30 °C.
Cyril Brunner, Benjamin T. Brem, Martine Collaud Coen, Franz Conen, Martin Steinbacher, Martin Gysel-Beer, and Zamin A. Kanji
Atmos. Chem. Phys., 22, 7557–7573, https://doi.org/10.5194/acp-22-7557-2022, https://doi.org/10.5194/acp-22-7557-2022, 2022
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Microscopic particles called ice-nucleating particles (INPs) are essential for ice crystals to form in clouds. INPs are a tiny proportion of atmospheric aerosol, and their abundance is poorly constrained. We study how the concentration of INPs changes diurnally and seasonally at a mountaintop station in central Europe. Unsurprisingly, a diurnal cycle is only found when considering air masses that have had lower-altitude ground contact. The highest INP concentrations occur in spring.
Cuiqi Zhang, Zhijun Wu, Jingchuan Chen, Jie Chen, Lizi Tang, Wenfei Zhu, Xiangyu Pei, Shiyi Chen, Ping Tian, Song Guo, Limin Zeng, Min Hu, and Zamin A. Kanji
Atmos. Chem. Phys., 22, 7539–7556, https://doi.org/10.5194/acp-22-7539-2022, https://doi.org/10.5194/acp-22-7539-2022, 2022
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The immersion ice nucleation effectiveness of aerosols from multiple sources in the urban environment remains elusive. In this study, we demonstrate that the immersion ice-nucleating particle (INP) concentration increased dramatically during a dust event in an urban atmosphere. Pollutant aerosols, including inorganic salts formed through secondary transformation (SIA) and black carbon (BC), might not act as effective INPs under mixed-phase cloud conditions.
Kunfeng Gao, Chong-Wen Zhou, Eszter J. Barthazy Meier, and Zamin A. Kanji
Atmos. Chem. Phys., 22, 5331–5364, https://doi.org/10.5194/acp-22-5331-2022, https://doi.org/10.5194/acp-22-5331-2022, 2022
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Incomplete combustion of fossil fuel produces carbonaceous particles called soot. These particles can affect cloud formation by acting as centres for droplet or ice formation. The atmospheric residence time of soot particles is of the order of days to weeks, which can result in them becoming coated by various trace species in the atmosphere such as acids. In this study, we quantify the cirrus cloud-forming ability of soot particles coated with the atmospherically ubiquitous sulfuric acid.
Zoé Brasseur, Dimitri Castarède, Erik S. Thomson, Michael P. Adams, Saskia Drossaart van Dusseldorp, Paavo Heikkilä, Kimmo Korhonen, Janne Lampilahti, Mikhail Paramonov, Julia Schneider, Franziska Vogel, Yusheng Wu, Jonathan P. D. Abbatt, Nina S. Atanasova, Dennis H. Bamford, Barbara Bertozzi, Matthew Boyer, David Brus, Martin I. Daily, Romy Fösig, Ellen Gute, Alexander D. Harrison, Paula Hietala, Kristina Höhler, Zamin A. Kanji, Jorma Keskinen, Larissa Lacher, Markus Lampimäki, Janne Levula, Antti Manninen, Jens Nadolny, Maija Peltola, Grace C. E. Porter, Pyry Poutanen, Ulrike Proske, Tobias Schorr, Nsikanabasi Silas Umo, János Stenszky, Annele Virtanen, Dmitri Moisseev, Markku Kulmala, Benjamin J. Murray, Tuukka Petäjä, Ottmar Möhler, and Jonathan Duplissy
Atmos. Chem. Phys., 22, 5117–5145, https://doi.org/10.5194/acp-22-5117-2022, https://doi.org/10.5194/acp-22-5117-2022, 2022
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The present measurement report introduces the ice nucleation campaign organized in Hyytiälä, Finland, in 2018 (HyICE-2018). We provide an overview of the campaign settings, and we describe the measurement infrastructure and operating procedures used. In addition, we use results from ice nucleation instrument inter-comparison to show that the suite of these instruments deployed during the campaign reports consistent results.
Kunfeng Gao, Franz Friebel, Chong-Wen Zhou, and Zamin A. Kanji
Atmos. Chem. Phys., 22, 4985–5016, https://doi.org/10.5194/acp-22-4985-2022, https://doi.org/10.5194/acp-22-4985-2022, 2022
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Soot particles impact cloud formation and radiative properties in the upper atmosphere where aircraft emit carbonaceous particles. We use cloud chambers to mimic the upper atmosphere temperature and humidity to test the influence of the morphology of the soot particles on ice cloud formation. For particles larger than 200 nm, the compacted (densified) samples have a higher affinity for ice crystal formation in the cirrus regime than the fluffy (un-compacted) soot particles of the same sample.
Ulrike Proske, Sylvaine Ferrachat, David Neubauer, Martin Staab, and Ulrike Lohmann
Atmos. Chem. Phys., 22, 4737–4762, https://doi.org/10.5194/acp-22-4737-2022, https://doi.org/10.5194/acp-22-4737-2022, 2022
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Cloud microphysical processes shape cloud properties and are therefore important to represent in climate models. Their parameterization has grown more complex, making the model results more difficult to interpret. Using sensitivity analysis we test how the global aerosol–climate model ECHAM-HAM reacts to changes to these parameterizations. The model is sensitive to the parameterization of ice crystal autoconversion but not to, e.g., self-collection, suggesting that it may be simplified.
Yu Wang, Aristeidis Voliotis, Dawei Hu, Yunqi Shao, Mao Du, Ying Chen, Judith Kleinheins, Claudia Marcolli, M. Rami Alfarra, and Gordon McFiggans
Atmos. Chem. Phys., 22, 4149–4166, https://doi.org/10.5194/acp-22-4149-2022, https://doi.org/10.5194/acp-22-4149-2022, 2022
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Aerosol water uptake plays a key role in atmospheric physicochemical processes. We designed chamber experiments on aerosol water uptake of secondary organic aerosol (SOA) from mixed biogenic and anthropogenic precursors with inorganic seed. Our results highlight this chemical composition influences the reconciliation of the sub- and super-saturated water uptake, providing laboratory evidence for understanding the chemical controls of water uptake of the multi-component aerosol.
Kristian Klumpp, Claudia Marcolli, and Thomas Peter
Atmos. Chem. Phys., 22, 3655–3673, https://doi.org/10.5194/acp-22-3655-2022, https://doi.org/10.5194/acp-22-3655-2022, 2022
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Surface interactions with solutes can significantly alter the ice nucleation activity of mineral dust. Past studies revealed the sensitivity of microcline, one of the most ice-active types of dust in the atmosphere, to inorganic solutes. This study focuses on the interaction of microcline with bio-organic substances and the resulting effects on its ice nucleation activity. We observe strongly hampered ice nucleation activity due to the presence of carboxylic and amino acids but not for polyols.
Jörg Wieder, Claudia Mignani, Mario Schär, Lucie Roth, Michael Sprenger, Jan Henneberger, Ulrike Lohmann, Cyril Brunner, and Zamin A. Kanji
Atmos. Chem. Phys., 22, 3111–3130, https://doi.org/10.5194/acp-22-3111-2022, https://doi.org/10.5194/acp-22-3111-2022, 2022
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We investigate the variation in ice-nucleating particles (INPs) relevant for primary ice formation in mixed-phased clouds over the Alps based on simultaneous in situ observations at a mountaintop and a nearby high valley (1060 m height difference). In most cases, advection from the surrounding lower regions was responsible for changes in INP concentration, causing a diurnal cycle at the mountaintop. Our study underlines the importance of the planetary boundary layer as an INP reserve.
Cyril Brunner, Benjamin T. Brem, Martine Collaud Coen, Franz Conen, Maxime Hervo, Stephan Henne, Martin Steinbacher, Martin Gysel-Beer, and Zamin A. Kanji
Atmos. Chem. Phys., 21, 18029–18053, https://doi.org/10.5194/acp-21-18029-2021, https://doi.org/10.5194/acp-21-18029-2021, 2021
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Special microscopic particles called ice-nucleating particles (INPs) are essential for ice crystals to form in the atmosphere. INPs are sparse and their atmospheric concentration and properties are not well understood. Mineral dust particles make up a significant fraction of INPs but how much remains unknown. Here, we address this knowledge gap by studying periods when mineral particles are present in large quantities at a mountaintop station in central Europe.
Larissa Lacher, Hans-Christian Clemen, Xiaoli Shen, Stephan Mertes, Martin Gysel-Beer, Alireza Moallemi, Martin Steinbacher, Stephan Henne, Harald Saathoff, Ottmar Möhler, Kristina Höhler, Thea Schiebel, Daniel Weber, Jann Schrod, Johannes Schneider, and Zamin A. Kanji
Atmos. Chem. Phys., 21, 16925–16953, https://doi.org/10.5194/acp-21-16925-2021, https://doi.org/10.5194/acp-21-16925-2021, 2021
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We investigate ice-nucleating particle properties at Jungfraujoch during the 2017 joint INUIT/CLACE field campaign, to improve the knowledge about those rare particles in a cloud-relevant environment. By quantifying ice-nucleating particles in parallel to single-particle mass spectrometry measurements, we find that mineral dust and aged sea spray particles are potential candidates for ice-nucleating particles. Our findings are supported by ice residual analysis and source region modeling.
Bernd Kärcher and Claudia Marcolli
Atmos. Chem. Phys., 21, 15213–15220, https://doi.org/10.5194/acp-21-15213-2021, https://doi.org/10.5194/acp-21-15213-2021, 2021
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Aerosol–cloud interactions play an important role in climate change. Simulations of the competition between homogeneous solution droplet freezing and heterogeneous ice nucleation can be compromised by the misapplication of ice-active particle fractions frequently derived from laboratory measurements or parametrizations. Our study frames the problem and establishes a solution that is easy to implement in cloud models.
Zane Dedekind, Annika Lauber, Sylvaine Ferrachat, and Ulrike Lohmann
Atmos. Chem. Phys., 21, 15115–15134, https://doi.org/10.5194/acp-21-15115-2021, https://doi.org/10.5194/acp-21-15115-2021, 2021
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The RACLETS campaign combined cloud and snow research to improve the understanding of precipitation formation in clouds. A numerical weather prediction model, COSMO, was used to assess the importance of ice crystal enhancement by ice–ice collisions for cloud properties. We found that the number of ice crystals increased by 1 to 3 orders of magnitude when ice–ice collisions were permitted to occur, reducing localized regions of high precipitation and, thereby, improving the model performance.
Paolo Pelucchi, David Neubauer, and Ulrike Lohmann
Geosci. Model Dev., 14, 5413–5434, https://doi.org/10.5194/gmd-14-5413-2021, https://doi.org/10.5194/gmd-14-5413-2021, 2021
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Stratocumulus are thin clouds whose cloud cover is underestimated in climate models partly due to overly low vertical resolution. We develop a scheme that locally refines the vertical grid based on a physical constraint for the cloud top. Global simulations show that the scheme, implemented only in the radiation routine, can increase stratocumulus cloud cover. However, this effect is poorly propagated to the simulated cloud cover. The scheme's limitations and possible ways forward are discussed.
Paraskevi Georgakaki, Aikaterini Bougiatioti, Jörg Wieder, Claudia Mignani, Fabiola Ramelli, Zamin A. Kanji, Jan Henneberger, Maxime Hervo, Alexis Berne, Ulrike Lohmann, and Athanasios Nenes
Atmos. Chem. Phys., 21, 10993–11012, https://doi.org/10.5194/acp-21-10993-2021, https://doi.org/10.5194/acp-21-10993-2021, 2021
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Aerosol and cloud observations coupled with a droplet activation parameterization was used to investigate the aerosol–cloud droplet link in alpine mixed-phase clouds. Predicted droplet number, Nd, agrees with observations and never exceeds a characteristic “limiting droplet number”, Ndlim, which depends solely on σw. Nd becomes velocity limited when it is within 50 % of Ndlim. Identifying when dynamical changes control Nd variability is central for understanding aerosol–cloud interactions.
Claudia Marcolli, Fabian Mahrt, and Bernd Kärcher
Atmos. Chem. Phys., 21, 7791–7843, https://doi.org/10.5194/acp-21-7791-2021, https://doi.org/10.5194/acp-21-7791-2021, 2021
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Pores are aerosol particle features that trigger ice nucleation, as they take up water by capillary condensation below water saturation that freezes at low temperatures. The pore ice can then grow into macroscopic ice crystals making up cirrus clouds. Here, we investigate the pores in soot aggregates responsible for pore condensation and freezing (PCF). Moreover, we present a framework to parameterize soot PCF that is able to predict the ice nucleation activity based on soot properties.
Fabiola Ramelli, Jan Henneberger, Robert O. David, Johannes Bühl, Martin Radenz, Patric Seifert, Jörg Wieder, Annika Lauber, Julie T. Pasquier, Ronny Engelmann, Claudia Mignani, Maxime Hervo, and Ulrike Lohmann
Atmos. Chem. Phys., 21, 6681–6706, https://doi.org/10.5194/acp-21-6681-2021, https://doi.org/10.5194/acp-21-6681-2021, 2021
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Orographic mixed-phase clouds are an important source of precipitation, but the ice formation processes within them remain uncertain. Here we investigate the origin of ice crystals in a mixed-phase cloud in the Swiss Alps using aerosol and cloud data from in situ and remote sensing observations. We found that ice formation primarily occurs in cloud top generating cells. Our results indicate that secondary ice processes are active in the feeder region, which can enhance orographic precipitation.
Fabiola Ramelli, Jan Henneberger, Robert O. David, Annika Lauber, Julie T. Pasquier, Jörg Wieder, Johannes Bühl, Patric Seifert, Ronny Engelmann, Maxime Hervo, and Ulrike Lohmann
Atmos. Chem. Phys., 21, 5151–5172, https://doi.org/10.5194/acp-21-5151-2021, https://doi.org/10.5194/acp-21-5151-2021, 2021
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Interactions between dynamics, microphysics and orography can enhance precipitation. Yet the exact role of these interactions is still uncertain. Here we investigate the role of low-level blocking and turbulence for precipitation by combining remote sensing and in situ observations. The observations show that blocked flow can induce the formation of feeder clouds and that turbulence can enhance hydrometeor growth, demonstrating the importance of local flow effects for orographic precipitation.
Ulrike Proske, Verena Bessenbacher, Zane Dedekind, Ulrike Lohmann, and David Neubauer
Atmos. Chem. Phys., 21, 5195–5216, https://doi.org/10.5194/acp-21-5195-2021, https://doi.org/10.5194/acp-21-5195-2021, 2021
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Ice crystals falling out of one cloud can initiate freezing in a second cloud below. We estimate the occurrence frequency of this natural cloud seeding over Switzerland from satellite data and sublimation calculations. We find that such situations with an ice cloud above another cloud are frequent and that the falling crystals survive the fall between two clouds in a significant number of cases, suggesting that natural cloud seeding is an important phenomenon over Switzerland.
Annika Lauber, Jan Henneberger, Claudia Mignani, Fabiola Ramelli, Julie T. Pasquier, Jörg Wieder, Maxime Hervo, and Ulrike Lohmann
Atmos. Chem. Phys., 21, 3855–3870, https://doi.org/10.5194/acp-21-3855-2021, https://doi.org/10.5194/acp-21-3855-2021, 2021
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An accurate prediction of the ice crystal number concentration (ICNC) is important to determine the radiation budget, lifetime, and precipitation formation of clouds. Even though secondary-ice processes can increase the ICNC by several orders of magnitude, they are poorly constrained and lack a well-founded quantification. During measurements on a mountain slope, a high ICNC of small ice crystals was observed just below 0 °C, attributed to a secondary-ice process and parametrized in this study.
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Short summary
Ice nucleation in the atmosphere influences cloud properties and lifetimes. Microfluidic instruments have recently been used to investigate ice nucleation, but these instruments are typically made out of a polymer that contributes to droplet instability over extended timescales and relatively high temperature uncertainty. To address these drawbacks, we develop and validate a new microfluidic instrument that uses fluoropolymer tubing to extend droplet stability and improve temperature accuracy.
Ice nucleation in the atmosphere influences cloud properties and lifetimes. Microfluidic...
