Articles | Volume 16, issue 20
https://doi.org/10.5194/amt-16-4885-2023
© Author(s) 2023. 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-16-4885-2023
© Author(s) 2023. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Research article
| 
26 Oct 2023
Research article |
| 26 Oct 2023
| 26 Oct 2023
Acoustic levitation of pollen and visualisation of hygroscopic behaviour
Sophie A. Mills
School of Geography, Earth and Environmental Sciences, University of Birmingham, Birmingham, B15 2TT, UK
Birmingham Institute of Forest Research, University of Birmingham, Birmingham, B15 2TT, UK
Adam Milsom
School of Geography, Earth and Environmental Sciences, University of Birmingham, Birmingham, B15 2TT, UK
Christian Pfrang
School of Geography, Earth and Environmental Sciences, University of Birmingham, Birmingham, B15 2TT, UK
Birmingham Institute of Forest Research, University of Birmingham, Birmingham, B15 2TT, UK
Department of Meteorology, University of Reading, Whiteknights, Earley Gate, Reading, RG6 6BB, UK
A. Rob MacKenzie
School of Geography, Earth and Environmental Sciences, University of Birmingham, Birmingham, B15 2TT, UK
Birmingham Institute of Forest Research, University of Birmingham, Birmingham, B15 2TT, UK
School of Geography, Earth and Environmental Sciences, University of Birmingham, Birmingham, B15 2TT, UK
Birmingham Institute of Forest Research, University of Birmingham, Birmingham, B15 2TT, UK
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EGUsphere, https://doi.org/10.5194/egusphere-2025-3839, https://doi.org/10.5194/egusphere-2025-3839, 2025
This preprint is open for discussion and under review for Atmospheric Measurement Techniques (AMT).
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We developed a multi-stage AutoML calibration framework to improve low-cost indoor PM2.5 sensor accuracy. Using chamber tests with varied emission sources, the method corrected drift, humidity effects, and non-linear responses, raising R2 above 0.9 and halving RMSE. The approach enables reliable, scalable indoor air quality monitoring for research and public health applications.
Andrea Mazzeo, Christian Pfrang, and Zaheer Ahmad Nasir
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Yuqing Dai, Bowen Liu, Chengxu Tong, David Carslaw, Robert MacKenzie, and Zongbo Shi
EGUsphere, https://doi.org/10.5194/egusphere-2025-1376, https://doi.org/10.5194/egusphere-2025-1376, 2025
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Susan E. Quick, Giulio Curioni, Nicholas J. Harper, Stefan Krause, and A. Robert MacKenzie
Biogeosciences, 22, 1557–1581, https://doi.org/10.5194/bg-22-1557-2025, https://doi.org/10.5194/bg-22-1557-2025, 2025
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To study the effects of rising CO2 levels on water usage of old-growth temperate oak forest, we monitored trees in an open-air elevated CO2 experiment for 5 years. We found 4 %–16 % leaf-on season reduction in daylight water usage for ~35% increase in atmospheric CO2. July-only reduction varied more widely. Tree water usage depended on tree size, i.e. stem size and projected canopy area, across all treatments. Experimental infrastructure increased the water usage of the trees in leaf-on season.
Rosalie H. Shepherd, Martin D. King, Andrew D. Ward, Edward J. Stuckey, Rebecca J. L. Welbourn, Neil Brough, Adam Milsom, Christian Pfrang, and Thomas Arnold
Atmos. Chem. Phys., 25, 2569–2588, https://doi.org/10.5194/acp-25-2569-2025, https://doi.org/10.5194/acp-25-2569-2025, 2025
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Adam Milsom, Adam M. Squires, Ben Laurence, Ben Wōden, Andrew J. Smith, Andrew D. Ward, and Christian Pfrang
Atmos. Chem. Phys., 24, 13571–13586, https://doi.org/10.5194/acp-24-13571-2024, https://doi.org/10.5194/acp-24-13571-2024, 2024
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We followed nano-structural changes in mixtures found in urban organic aerosol emissions (oleic acid, sodium oleate and fructose) during humidity change and ozone exposure. We demonstrate that self-assembly of fatty acid nanostructures can impact water uptake and chemical reactivity, affecting atmospheric lifetimes, urban air quality (preventing harmful emissions from degradation and enabling their long-range transport) and climate (affecting cloud formation), with implications for human health.
Adam Milsom, Shaojun Qi, Ashmi Mishra, Thomas Berkemeier, Zhenyu Zhang, and Christian Pfrang
Atmos. Chem. Phys., 23, 10835–10843, https://doi.org/10.5194/acp-23-10835-2023, https://doi.org/10.5194/acp-23-10835-2023, 2023
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Aerosols and films are found indoors and outdoors. Our study measures and models reactions of a cooking aerosol proxy with the atmospheric oxidant ozone relying on a low-cost but sensitive technique based on mass changes and film rigidity. We found that film morphology changed and film rigidity increased with evidence of surface crust formation during ozone exposure. Our modelling results demonstrate clear potential to take this robust method to the field for reaction monitoring.
Clarissa Baldo, Paola Formenti, Claudia Di Biagio, Gongda Lu, Congbo Song, Mathieu Cazaunau, Edouard Pangui, Jean-Francois Doussin, Pavla Dagsson-Waldhauserova, Olafur Arnalds, David Beddows, A. Robert MacKenzie, and Zongbo Shi
Atmos. Chem. Phys., 23, 7975–8000, https://doi.org/10.5194/acp-23-7975-2023, https://doi.org/10.5194/acp-23-7975-2023, 2023
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This paper presents new shortwave spectral complex refractive index and single scattering albedo data for Icelandic dust. Our results show that the imaginary part of the complex refractive index of Icelandic dust is at the upper end of the range of low-latitude dust. Furthermore, we observed that Icelandic dust is more absorbing towards the near-infrared, which we attribute to its high magnetite content. These findings are important for modeling dust aerosol radiative effects in the Arctic.
Edward J. Bannister, Mike Jesson, Nicholas J. Harper, Kris M. Hart, Giulio Curioni, Xiaoming Cai, and A. Rob MacKenzie
Atmos. Chem. Phys., 23, 2145–2165, https://doi.org/10.5194/acp-23-2145-2023, https://doi.org/10.5194/acp-23-2145-2023, 2023
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In forests, the residence time of air influences canopy chemistry and atmospheric exchange. However, there have been few field observations. We use long-term open-air CO2 enrichment measurements to show median daytime residence times are twice as long when the trees are in leaf versus when they are not. Residence times increase with increasing atmospheric stability and scale inversely with turbulence. Robust parametrisations for large-scale models are available using common distributions.
Adam Milsom, Amy Lees, Adam M. Squires, and Christian Pfrang
Geosci. Model Dev., 15, 7139–7151, https://doi.org/10.5194/gmd-15-7139-2022, https://doi.org/10.5194/gmd-15-7139-2022, 2022
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Andrea Mazzeo, Michael Burrow, Andrew Quinn, Eloise A. Marais, Ajit Singh, David Ng'ang'a, Michael J. Gatari, and Francis D. Pope
Atmos. Chem. Phys., 22, 10677–10701, https://doi.org/10.5194/acp-22-10677-2022, https://doi.org/10.5194/acp-22-10677-2022, 2022
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A modelling system for meteorology and chemistry transport processes, WRF–CHIMERE, has been tested and validated for three East African conurbations using the most up-to-date anthropogenic emissions available. Results show that the model is able to reproduce hourly and daily temporal variabilities in aerosol concentrations that are close to observations in both urban and rural environments, encouraging the adoption of numerical modelling as a tool for air quality management in East Africa.
Dimitrios Bousiotis, David C. S. Beddows, Ajit Singh, Molly Haugen, Sebastián Diez, Pete M. Edwards, Adam Boies, Roy M. Harrison, and Francis D. Pope
Atmos. Meas. Tech., 15, 4047–4061, https://doi.org/10.5194/amt-15-4047-2022, https://doi.org/10.5194/amt-15-4047-2022, 2022
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Tony Bush, Nick Papaioannou, Felix Leach, Francis D. Pope, Ajit Singh, G. Neil Thomas, Brian Stacey, and Suzanne Bartington
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Aileen B. Baird, Edward J. Bannister, A. Robert MacKenzie, and Francis D. Pope
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Forest environments contain a wide variety of airborne biological particles (bioaerosols) important for plant and animal health and biosphere–atmosphere interactions. Using low-cost sensors and a free-air carbon dioxide enrichment (FACE) experiment, we monitor the impact of enhanced CO2 on airborne particles. No effect of the enhanced CO2 treatment on total particle concentrations was observed, but a potential suppression of high concentration bioaerosol events was detected under enhanced CO2.
Adam Milsom, Adam M. Squires, Andrew D. Ward, and Christian Pfrang
Atmos. Chem. Phys., 22, 4895–4907, https://doi.org/10.5194/acp-22-4895-2022, https://doi.org/10.5194/acp-22-4895-2022, 2022
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Cooking emissions can self-organise into nanostructured lamellar bilayers, and this can influence reaction kinetics. We developed a kinetic multi-layer model-based description of decay data we obtained from laboratory experiments of the ozonolysis of coated films of such a self-organised system, demonstrating a decreased diffusivity for both oleic acid and ozone. Nanostructure formation can thus increase the reactive half-life of oleic acid by days under typical indoor and outdoor conditions.
Leigh R. Crilley, Louisa J. Kramer, Francis D. Pope, Chris Reed, James D. Lee, Lucy J. Carpenter, Lloyd D. J. Hollis, Stephen M. Ball, and William J. Bloss
Atmos. Chem. Phys., 21, 18213–18225, https://doi.org/10.5194/acp-21-18213-2021, https://doi.org/10.5194/acp-21-18213-2021, 2021
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Nitrous acid (HONO) is a key source of atmospheric oxidants. We evaluate if the ocean surface is a source of HONO for the marine boundary layer, using measurements from two contrasting coastal locations. We observed no evidence for a night-time ocean surface source, in contrast to previous work. This points to significant geographical variation in the predominant HONO formation mechanisms in marine environments, reflecting possible variability in the sea-surface microlayer composition.
Adam Milsom, Adam M. Squires, Jacob A. Boswell, Nicholas J. Terrill, Andrew D. Ward, and Christian Pfrang
Atmos. Chem. Phys., 21, 15003–15021, https://doi.org/10.5194/acp-21-15003-2021, https://doi.org/10.5194/acp-21-15003-2021, 2021
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Atmospheric aerosols can be solid, semi-solid or liquid. This phase state may impact key aerosol processes such as oxidation and water uptake, affecting cloud droplet formation and urban air pollution. We have observed a solid crystalline organic phase in a levitated proxy for cooking emissions, oleic acid. Spatially resolved structural changes were followed during ageing by X-ray scattering, revealing phase gradients, aggregate products and a markedly reduced ozonolysis reaction rate.
Dimitrios Bousiotis, Francis D. Pope, David C. S. Beddows, Manuel Dall'Osto, Andreas Massling, Jakob Klenø Nøjgaard, Claus Nordstrøm, Jarkko V. Niemi, Harri Portin, Tuukka Petäjä, Noemi Perez, Andrés Alastuey, Xavier Querol, Giorgos Kouvarakis, Nikos Mihalopoulos, Stergios Vratolis, Konstantinos Eleftheriadis, Alfred Wiedensohler, Kay Weinhold, Maik Merkel, Thomas Tuch, and Roy M. Harrison
Atmos. Chem. Phys., 21, 11905–11925, https://doi.org/10.5194/acp-21-11905-2021, https://doi.org/10.5194/acp-21-11905-2021, 2021
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Formation of new particles is a key process in the atmosphere. New particle formation events arising from nucleation of gaseous precursors have been analysed in extensive datasets from 13 sites in five European countries in terms of frequency, nucleation rate, and particle growth rate, with several common features and many differences identified. Although nucleation frequencies are lower at roadside sites, nucleation rates and particle growth rates are typically higher.
Dimitrios Bousiotis, Ajit Singh, Molly Haugen, David C. S. Beddows, Sebastián Diez, Killian L. Murphy, Pete M. Edwards, Adam Boies, Roy M. Harrison, and Francis D. Pope
Atmos. Meas. Tech., 14, 4139–4155, https://doi.org/10.5194/amt-14-4139-2021, https://doi.org/10.5194/amt-14-4139-2021, 2021
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Measurement and source apportionment of atmospheric pollutants are crucial for the assessment of air quality and the implementation of policies for their improvement. This study highlights the current capability of low-cost sensors in source identification and differentiation using clustering approaches. Future directions towards particulate matter source apportionment using low-cost OPCs are highlighted.
Dimitrios Bousiotis, James Brean, Francis D. Pope, Manuel Dall'Osto, Xavier Querol, Andrés Alastuey, Noemi Perez, Tuukka Petäjä, Andreas Massling, Jacob Klenø Nøjgaard, Claus Nordstrøm, Giorgos Kouvarakis, Stergios Vratolis, Konstantinos Eleftheriadis, Jarkko V. Niemi, Harri Portin, Alfred Wiedensohler, Kay Weinhold, Maik Merkel, Thomas Tuch, and Roy M. Harrison
Atmos. Chem. Phys., 21, 3345–3370, https://doi.org/10.5194/acp-21-3345-2021, https://doi.org/10.5194/acp-21-3345-2021, 2021
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New particle formation events from 16 sites over Europe have been studied, and the influence of meteorological and atmospheric composition variables has been investigated. Some variables, like solar radiation intensity and temperature, have a positive effect on the occurrence of these events, while others have a negative effect, affecting different aspects such as the rate at which particles are formed or grow. This effect varies depending on the site type and magnitude of these variables.
Benjamin Woden, Maximilian W. A. Skoda, Adam Milsom, Curtis Gubb, Armando Maestro, James Tellam, and Christian Pfrang
Atmos. Chem. Phys., 21, 1325–1340, https://doi.org/10.5194/acp-21-1325-2021, https://doi.org/10.5194/acp-21-1325-2021, 2021
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Atmospheric aerosols contain a large amount of organic compounds, whose oxidation affects their physical properties through a process known as ageing. We have simulated atmospheric ageing experimentally to elucidate the nature and behaviour of residual surface films. Our results show an increasing amount of residue at near-zero temperatures, demonstrating that an inert product film may build up during droplet ageing, even if only ordinarily short-lived reactive species are initially emitted.
Clarissa Baldo, Paola Formenti, Sophie Nowak, Servanne Chevaillier, Mathieu Cazaunau, Edouard Pangui, Claudia Di Biagio, Jean-Francois Doussin, Konstantin Ignatyev, Pavla Dagsson-Waldhauserova, Olafur Arnalds, A. Robert MacKenzie, and Zongbo Shi
Atmos. Chem. Phys., 20, 13521–13539, https://doi.org/10.5194/acp-20-13521-2020, https://doi.org/10.5194/acp-20-13521-2020, 2020
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We showed that Icelandic dust has a fundamentally different chemical and mineralogical composition from low-latitude dust. In particular, magnetite is as high as 1 %–2 % of the total dust mass. Our results suggest that Icelandic dust may have an important impact on the radiation balance in the subpolar and polar regions.
Mohammed S. Alam, Leigh R. Crilley, James D. Lee, Louisa J. Kramer, Christian Pfrang, Mónica Vázquez-Moreno, Milagros Ródenas, Amalia Muñoz, and William J. Bloss
Atmos. Meas. Tech., 13, 5977–5991, https://doi.org/10.5194/amt-13-5977-2020, https://doi.org/10.5194/amt-13-5977-2020, 2020
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We report on the interference arising in measurements of nitrogen oxides (NOx) from the presence of a range of alkenes in sampled air when using the most widespread air quality monitoring technique for chemiluminescence detection. Interferences of up to 11 % are reported, depending upon the alkene present and conditions used. Such interferences may be of substantial importance for the interpretation of ambient NOx data, particularly for high volatile organic compound and low NOx environments.
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Short summary
Pollen grains are important components of the atmosphere and have the potential to impact upon cloud processes via their ability to help in the formation of rain droplets. This study investigates the hygroscopicity of two different pollen species using an acoustic levitator. Pollen grains are levitated, and their response to changes in relative humidity is investigated. A key advantage of this method is that it is possible study pollen shape under varying environmental conditions.
Pollen grains are important components of the atmosphere and have the potential to impact upon...
