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Hire Dr. James B.

United Kingdom

USD 100 /hr

Data Science, Scientific Analytics & Technical Writing

Profile Summary

I specialise in extracting meaning from complex, high-dimensional scientific datasets — applying machine learning, source apportionment, and bespoke modelling to problems where standard approaches fall short. With 24 peer-reviewed publications (including a Nature Geoscience cover) and a track record of delivering analytical frameworks to international research teams and policymakers, I bring rigorous, reproducible data science to clients who need more than off-the-shelf solutions. I also translate complex science into clear, compelling outputs — whether peer-reviewed manuscripts, policy briefs, technical reports, or stakeholder communications — with experience writing for audiences ranging from funding bodies to government advisors. Services: predictive modelling · dimensionality reduction · time-series analysis · custom ML pipelines · manuscript preparation · policy and regulatory writing · stakeholder reporting.

Subject Matter Expertise

• ☆ Data Analysis
• ☆ Computer Simulation/Computational Modeling
• ☆ Predictive Modeling & Analytics
• ☆ Data Processing
• ☆ Data Exploration
• ☆ Cluster Analysis
• ☆ Data Visualization
• ☆ Data Collection
• ☆ Data Management
• ☆ Data Manipulation
• ☆ Machine Learning
• ☆ Text Mining & Analytics
• ☆ Data Mining
• ☆ Data Cleaning
• ☆ Natural Language Processing
• ☆ Neural Networks
• ☆ Pattern Recognition
• ☆ Artificial Intelligence
• ☆ Deep Learning
• ☆ Computer Vision
• ☆ Statistics
• ☆ Applied Statistics
• ☆ Regression Analysis
• ☆ Multivariate Analysis
• ☆ Nonlinear Regression
• ☆ Study Design
• ☆ Trend Analysis
• ☆ Environmental Science
• ☆ Pollution Control & Waste Management
• ☆ Air Pollution
• ☆ Air Quality Management
• ☆ Environmental Management & Protection
• ☆ Environmental Policy
• ☆ Environmental Health
• ☆ Environmental Chemistry
• ☆ Environmental Statistics
• ☆ Applied Mathematics
• ☆ Library & Information Science
• ☆ Abstracting & Indexing
• ☆ Python
• ☆ SQL
• ☆ Excel
• ☆ Tensorflow
• ☆ LaTex
• ☆ R
• ☆ Scikit-learn
• ☆ Markup Languages
• ☆ Peer Review
• ☆ Research Methodology
• ☆ Fact Checking
• ☆ Literature Search
• ☆ Gray Literature Search
• ☆ Technical & Scientific Writing
• ☆ Journal Selection
• ☆ Manuscript & Journal Article Writing
• ☆ Instructional Materials
• ☆ Experimental Protocols
• ☆ Science Communication
• ☆ Literature Review
• ☆ Traditional/Narrative Literature Review
• ☆ Systematic Literature Review

Services

• Writing
• Research
• Consulting
• Data & AI

Writing Technical Writing

Research Fact Checking, Gray Literature Search, Scientific and Technical Research, Systematic Literature Review

Consulting Scientific and Technical Consulting

Data & AI Predictive Modeling, Statistical Analysis, Image Processing, Data Visualization, Big Data Analytics, Text Mining & Analytics, Data Mining, Data Cleaning, Data Processing, Data Insights

Work Experience

The University of Birmingham

- Present

Assistant Professor

University of Birmingham

June 2026 - Present

Postdoctoral Researcher

University of Birmingham

March 2020 - May 2026

Education

The University of Birmingham

- Present

Ph.D Atmospheric Chemistry (School of Geography, Earth and Environmental Sciences )

University of Birmingham

October 2016 - August 2020

B.Sc Chemistry (School of Geography, Earth and Environmental Sciences )

University of Plymouth

October 2013 - July 2016

Certifications

• Project Management

  APM

  May 2026 - December 2026

Publications

JOURNAL ARTICLE

Continental river runoff enhances atmospheric aerosol formation over the Arctic Ocean @article{0440790d0f324069abedeabc634d00e7, title = "Continental river runoff enhances atmospheric aerosol formation over the Arctic Ocean", abstract = "The formation of cloud condensation nuclei is a critical but uncertain factor in Arctic climate dynamics. A major nuclei contributor is new particle formation, yet the geographical variations in activity and the factors driving it remain poorly understood. Here, we present a nine-year (2010–2018) analysis of atmospheric particle number size distributions from Tiksi, Russia, integrated with air mass trajectory modelling and ocean remote sensing. We show that aerosol formation rates are significantly enhanced—particle formation rates increase by 300\% and growth rates by 60\%—when air masses travel over regions of the Arctic Ocean with high concentrations of terrigenous dissolved organic matter from river runoff. Using multiple analytical approaches, we identify terrigenous dissolved organic matter rich waters as key source regions for aerosol formation, likely driven by the oxidation of biotic and abiotic volatile organic compounds emitted from the air–ocean interface. We note that most atmospheric measurements are conducted far from Arctic River deltas, despite 11\% of the ice-free Arctic Ocean being influenced by high terrigenous dissolved organic matter concentrations. Our findings indicate that riverine input and subsequent aerosol formation is a major source of Arctic aerosol which has been largely overlooked.", author = "James Brean and Fichot, \{C{\'e}dric G.\} and Beddows, \{David C. S.\} and Douglas Worsnop and Zongbo Shi and Harrison, \{Roy M.\} and Eija Asmi and Manuel Dall´Osto", note = "Publisher Copyright: {\textcopyright} The Author(s) 2025.", year = "2026", month = jan, day = "22", doi = "10.1038/s43247-025-02986-8", language = "English", volume = "7", journal = "Communications Earth and Environment", issn = "2662-4435", publisher = "Nature Research", number = "1", } . Communications Earth and Environment.

Multiple oceanic sources of alkylamines in Southern Ocean atmospheres @article{80c389526ad84524bb490dc435ecb48f, title = "Multiple oceanic sources of alkylamines in Southern Ocean atmospheres", abstract = "Measurements of pre-industrial conditions are of paramount importance for understanding historical climate change. The Southern Ocean and Antarctic continent are some of the least polluted environments on planet Earth. Alkylamines can rapidly partition into aerosols, increasing their mass, as well as form new particles altogether. We demonstrate the importance of pelagic “open ocean” (OO) and sympagic “sea ice” (SI) regions in supplying distinct organic nitrogen aerosol components. In the aerosol phase, dimethylamine (DMA) and trimethylamine (TMA) are both secondary, though DMA likely originates mainly from pelagic regions, while TMA is associated mainly with sympagic regions. Parallel measurements in ice and surface waters reveal that melting sea ice contains a factor of four more TMA than coastal Antarctic Peninsula waters; and seventeen times more TMA than OO regions - suggesting additional coastal Antarctic sources. To better interpret future climate change, we recommend employing regional atmospheric chemistry models to understand these diverse aerosol sources.", author = "Manuel Dall'Osto and Fitzsimons, \{Mark F.\} and James Brean and Akenga, \{Preston Chebai\} and A. Jones and Tom Lachlan-Cope and Ana Sotomayor and Elisa Berdalet and Dolors Vaque and Harrison, \{Roy M.\} and Karam Mansour and Matteo Rinaldi and Stefano Decesari and David Beddows and Marco Paglione", year = "2026", month = jan, day = "14", doi = "10.1038/s41612-025-01284-6", language = "English", volume = "9", journal = "npj Climate and Atmospheric Science", issn = "2397-3722", publisher = "Nature Research", number = "1", } . npj Climate and Atmospheric Science.

Risks of increased ultrafine particles associated with transition to a carbon-neutral world @article{4f9d24a2db7d428e996a8227a0559e93, title = "Risks of increased ultrafine particles associated with transition to a carbon-neutral world", abstract = "Decades of successful air quality policies have significantly reduced fine particulate matter (PM2.5) concentrations, a major public health achievement. This success, however, presents an atmospheric paradox. The reduction in PM2.5 mass has lowered the atmospheric condensation sink, which normally scavenges the molecular clusters that initiate new particle formation (NPF). This creates more favourable conditions for the formation of smaller, potentially more hazardous, ultrafine particles (UFPs). Furthermore, technologies central to net-zero strategies, such as amine-based carbon capture, risk creating new, concentrated sources of potent NPF precursors. This confluence of factors exposes a critical blind spot in air quality management. Current regulations and industrial risk assessments are almost exclusively mass-based, overlooking particle number concentrations and the associated health risks of UFPs. This article argues that the pursuit of climate goals must not create unforeseen public health burdens. It calls for the strategic integration of particle number and size distribution measurements into existing air quality networks to build the evidence base needed to validate models, inform future policy, and ensure that climate solutions do not inadvertently establish a new generation of localised air pollution problems.", author = "James Brean and Roy Harrison", year = "2025", month = dec, day = "8", doi = "10.26599/TRCN.2025.9550015", language = "English", volume = "1", journal = "Technology Review for Carbon Neutrality", issn = "3007-6544", publisher = "Tsinghua University Press", number = "2025", } . Technology Review for Carbon Neutrality.

Wide-Positive Matrix Factorisation of particle number size distributions @article{3af913f86e134ca99b1f4d10044b0bb7, title = "Wide-Positive Matrix Factorisation of particle number size distributions: A new approach accounting for cyclically changing source profiles", abstract = "Particle number size distributions (PNSDs) in the atmosphere are a composite from various sources, and Positive Matrix Factorization (PMF) is commonly used to identify these sources by separating the data into multiple factors, each representing a source which is assumed to emit a constant PNSD over time. However, assuming a constant PNSD for each source overlooks the regular growth and shrinkage of atmospheric particles, which often follow diurnal cycles. {\textquoteleft}Wide-PMF{\textquoteright} restructures the data matrix to place each hourly observation side-by-side; each wide-PMF factor represents a diurnal cycle in the PNSD, capturing formation, emission, growth, shrinkage, and losses, unlike narrow-PMF which presents a time-invariant size distribution whose diurnal cycle has to be inferred from the G-matrix. Using data measured at an urban background site, Wide-PMF reveals diurnal trends in PNSD from each source, and is able to separate photochemical nucleation from traffic nucleation, which are typically inadequately resolved in narrow PMF.", keywords = "Positive Matrix Factorisation, PMF, Atmospheric particles, Number size distribution, Long data series", author = "D.C.S. Beddows and J. Brean and A. Rowell and M. Merkel and K. Weinhold and M. Dall'osto and R.M. Harrison", year = "2025", month = oct, day = "10", doi = "10.1016/j.scitotenv.2025.180231", language = "English", volume = "998", journal = "Science of the Total Environment", issn = "0048-9697", publisher = "Elsevier", } . Science of the Total Environment.

Traffic-Emitted Amines Promote New Particle Formation at Roadsides @article{6db1263b2dc3422aadbac19dc86d2ec3, title = "Traffic-Emitted Amines Promote New Particle Formation at Roadsides", abstract = "New particle formation (NPF) is a major source of atmospheric aerosol particles, significantly influencing particle number concentrations in urban environments. High condensation and coagulation sinks at highly trafficked roadside sites should suppress NPF due to the low survival probability of clusters and new particles, however, observations show that roadside NPF is frequent and intense. Here, we investigate NPF at an urban background and roadside site in Central Europe using simultaneous measurements of sulfuric acid, amines, highly oxygenated organic molecules (HOMs), and particle number size distributions. We demonstrate that sulfuric acid and amines, particularly traffic-derived C2-amines, are the primary participants in particle formation. C2-amine concentrations at the roadside are enhanced by over a factor of 4 relative to the background, overcoming the effect of enhanced coagulation and condensation sinks. Using machine learning we identify a further but uncertain enhancing role of HOMs. These findings reveal the critical role of traffic emissions in urban NPF.", author = "James Brean and Federica Bortolussi and Alex Rowell and David Beddows and Kay Weinhold and Peter Mettke and Maik Merkel and Avinash Kumar and Shawon Barua and Siddharth Iyer and Alexandra Karppinen and Hilda Sandstr{\"o}m and Patrick Rinke and Alfred Wiedensohler and Mira P{\"o}hlker and \{Dal Maso\}, Miikka and Matti Rissanen and Zongbo Shi and Harrison, \{Roy M.\}", year = "2025", month = jul, day = "16", doi = "10.1021/acsestair.5c00119", language = "English", journal = "ACS ES\&T Air", issn = "2837-1402", publisher = "American Chemical Society", } . ACS ES&T Air.

A coupled fluids-chemistry model for pollutant dynamics indoors—Application to a kitchen scenario @article{09754546700f49edaaf714665a70e853, title = "A coupled fluids-chemistry model for pollutant dynamics indoors—Application to a kitchen scenario", abstract = "Indoor air quality (IAQ) is a critical factor influencing human health, particularly in confined spaces such as kitchens, where cooking activities release harmful pollutants. This study presents a novel modeling framework—ChemFlow3D—combining an in-house computational fluid dynamics (CFD) solver with a chemical reaction module to simulate the dynamics of both pollutant dispersion and transformation in a residential kitchen. The model captures the intricate interplay between fluid flow and chemical kinetics and is validated against experimental data for accuracy and reliability. Using this approach, the spatial and temporal distributions of common indoor air pollutants, including particulate matter (PM2.5), nitrogen oxides (NO and NO2), a generic volatile organic compounds (RH), and carbon monoxide (CO), were examined under various natural and mechanical ventilation strategies. The study also explored the impact of including chemical reactions on pollutant concentrations and compared this with simulations that neglected such reactions. The results show ChemFlow3D's ability to simultaneously account for ventilation strategies, pollutant transport, and chemical reactions. Validated against real-world measurements, the model successfully captures the evolution of indoor pollutants during cooking and demonstrates its robustness in simulating complex ventilation conditions. Additionally, the findings underscore the importance of accounting for chemical reactions, as reactive pollutants like NO2 exhibited notable transformations that were otherwise neglected. This work provides actionable insights into ventilation system design and optimization to mitigate indoor air pollution. It highlights the potential of integrating CFD and chemical kinetics for advancing IAQ research, offering a robust methodology to track the spatiotemporal evolution of pollutants in enclosed spaces.", author = "Zhen Liu and Christian Pfrang and Roberto Sommariva and James Brean and Yizhou Su and William Bloss and Bru{\~n}o Fraga", year = "2025", month = may, day = "27", doi = "10.1063/5.0270416", language = "English", volume = "37", journal = "Physics of Fluids", issn = "1070-6631", publisher = "American Institute of Physics", number = "5", } . Physics of Fluids.

Multiple eco-regions contribute to the seasonal cycle of Antarctic aerosol size distributions @article{300be18ba29e480987a59cb293bb8a9b, title = "Multiple eco-regions contribute to the seasonal cycle of Antarctic aerosol size distributions", abstract = "In order to reduce the uncertainty of aerosol radiative forcing in global climate models, we need to better understand natural aerosol sources which are important to constrain the current and pre-industrial climate. Here, we analyse particle number size distributions (PNSDs) collected during a year (2015) across four coastal and inland Antarctic research bases (Halley, Marambio, Dome C and King Sejong). We utilise k-means cluster analysis to separate the PNSD data into six main categories. “Nucleation” and “bursting” PNSDs occur 28 \%–48 \% of the time between sites, most commonly at the coastal sites of Marambio and King Sejong where air masses mostly come from the west and travel over extensive regions of sea ice, marginal ice and open ocean and likely arise from new particle formation. “Aitken high”, “Aitken low” and “bimodal” PNSDs occur 37 \%–68 \% of the time, most commonly at Dome C on the Antarctic Plateau, and likely arise from atmospheric transport and ageing from aerosol originating likely in both the coastal boundary layer and free troposphere. “Pristine” PNSDs with low aerosol concentrations occur 12 \%–45 \% of the time, most commonly at Halley, located at low altitudes and far from the coastal melting ice and influenced by air masses from the west. Not only the sea spray primary aerosols and gas to particle secondary aerosol sources, but also the different air masses impacting the research stations should be kept in mind when deliberating upon different aerosol precursor sources across research stations. We infer that both primary and secondary components from pelagic and sympagic regions strongly contribute to the annual seasonal cycle of Antarctic aerosols. Our simultaneous aerosol measurements stress the importance of the variation in atmospheric biogeochemistry across the Antarctic region.", author = "James Brean and Beddows, \{David C. S.\} and Eija Asmi and Aki Virkkula and Qu{\'e}l{\'e}ver, \{Lauriane L. J.\} and Mikko Sipil{\"a} and \{Den Heuvel\}, \{Floortje Van\} and Thomas Lachlan-Cope and Anna Jones and Markus Frey and Angelo Lupi and Jiyeon Park and Yoon, \{Young Jun\} and Rolf Weller and Marincovich, \{Giselle L.\} and Mulena, \{Gabriela C.\} and Harrison, \{Roy M.\} and Manuel DallOsto", note = "Copyright: {\textcopyright} 2025 James Brean et al.", year = "2025", month = jan, day = "28", doi = "10.5194/acp-25-1145-2025", language = "English", volume = "25", pages = "1145--1162", journal = "Atmospheric Chemistry and Physics", issn = "1680-7316", publisher = "Copernicus Publications", number = "2", } . Atmospheric Chemistry and Physics.

The behaviour of charged particles (ions) during new particle formation events in urban Leipzig, Germany @article{8fb9aaee08174e38b3b0c05001c44f4e, title = "The behaviour of charged particles (ions) during new particle formation events in urban Leipzig, Germany", abstract = "Air ions are electrically charged particles in air. They are ubiquitous in the natural environment and affect the Earth's radiation budget by accelerating the formation and growth of new aerosol particles. Despite this, few datasets exist exploring these effects in the urban environment. A neutral cluster and air ion spectrometer was deployed in Leipzig, Germany, to measure the number size distribution of charged particles from 0.8 to 42 nm, between 27 July and 25 August 2022. Following previous analyses, charged particles were classified into small (0.8-1.6 nm), intermediate (1.6-7.5 nm), and large (7.5-22 nm) fractions by mass diameter, and their mean concentrations (sum of positive and negative polarities) during the campaign were 405, 71.6, and 415 cm-3, respectively. The largest peaks in intermediate and large ions were explained by new particle formation (NPF), with intermediate ions correlating well with sulfuric acid dimer. Smaller morning and evening peaks were coincident with black carbon concentrations and attributed to primary emissions. NPF events, observed on 30 \% of days, coincided with intense solar radiation and elevated sulfuric acid dimer. Small charged particles were primarily associated with radioactive decay and highest during the early hours, and they are unrelated to primary emissions or NPF. The apparent contributions of charged particles to 3 and 7.5 nm particle formation rates were 5.7 \% and 12.7 \%, respectively, with mean growth rates of 4.0 nm h-1 between 3-7.5 nm and 5.2 nm h-1 between 7.5 and 22 nm. The ratio of charged to total particle formation rates at 3 nm suggests a minor role for charged particles in NPF. We conclude that NPF is a primary source of > 3 nm ions in our data, with primary emissions being the major source in the absence of NPF.", author = "Alex Rowell and James Brean and Beddows, \{David C.S.\} and Zongbo Shi and Avinash Kumar and Matti Rissanen and \{Dal Maso\}, Miikka and Peter Mettke and Kay Weinhold and Maik Merkel and Harrison, \{Roy M.\}", note = "Publisher Copyright: {\textcopyright} 2024 Alex Rowell et al.", year = "2024", month = sep, day = "18", doi = "10.5194/acp-24-10349-2024", language = "English", volume = "24", pages = "10349--10361", journal = "Atmospheric Chemistry and Physics", issn = "1680-7316", publisher = "Copernicus Publications", number = "18", } . Atmospheric Chemistry and Physics.

James Brean, Alex Rowell, David C. S. Beddows, Tuukka Petäjä, Máté Vörösmarty, Imre Salma, Jarkko V. Niemi, Hanna E. Manninen, Dominik van Pinxteren, Thomas Tuch, et al. (2024). Insights into the sources of ultrafine particle numbers at six European urban sites obtained by investigating COVID-19 lockdowns . Atmospheric Chemistry and Physics.

Insights into the sources of ultrafine particle numbers at six European urban sites obtained by investigating COVID-19 lockdowns @article{53792e60fabd45d0b36cd81d3c38d026, title = "Insights into the sources of ultrafine particle numbers at six European urban sites obtained by investigating COVID-19 lockdowns", abstract = "Lockdown restrictions in response to the COVID-19 pandemic led to the curtailment of many activities and reduced emissions of primary air pollutants. Here, we applied positive matrix factorisation to particle size distribution (PSD) data from six monitoring sites (three urban background and three roadside) between four European cities (Helsinki, Leipzig, Budapest, and London) to evaluate how particle number concentrations (PNCs) and their sources changed during the respective 2020 lockdown periods compared to the reference years 2014-2019. A number of common factors were resolved between sites, including nucleation, road traffic semi-volatile fraction (road trafficsvf), road traffic solid fraction (road trafficsf), diffuse urban (wood smoke + aged traffic), ozone-Associated secondary aerosol (O3-associated SA), and secondary inorganic aerosol (SIA). Nucleation, road traffic, and diffuse urban factors were the largest contributors to mean PNCs during the reference years and respective lockdown periods. However, SIA factors were the largest contributors to particle mass concentrations, irrespective of environment type. Total mean PNCs were lower at two of the urban-background and all roadside sites during lockdown. The response of nucleation and road trafficsvf factors to lockdown restrictions was highly variable, although road trafficsf factors were consistently lower at roadside sites. The responses of diffuse urban factors were largely consistent and were mostly lower at urban-background sites. Secondary aerosols (O3-Associated SA and SIA) exhibited extensive reductions in their mean PNCs at all sites. These variegated responses to lockdowns across Europe point to a complex network of sources and aerosol sinks contributing to PSDs.", author = "Alex Rowell and James Brean and David Beddows and Tuukka Pet{\"a}j{\"a} and M{\'a}t{\'e} V{\"o}r{\"o}smarty and Imre Salma and Niemi, \{Jarkko V.\} and Manninen, \{Hanna E.\} and \{Van Pinxteren\}, Dominik and Thomas Tuch and Kay Weinhold and Zongbo Shi and Harrison, \{Roy M.\}", note = "Publisher Copyright: {\textcopyright} 2024 Alex Rowell et al.", year = "2024", month = aug, day = "29", doi = "10.5194/acp-24-9515-2024", language = "English", volume = "24", pages = "9515--9531", journal = "Atmospheric Chemistry and Physics", issn = "1680-7316", publisher = "Copernicus Publications", number = "16", } . Atmospheric Chemistry and Physics.

Measurements of particulate methanesulfonic acid above the remote Arctic Ocean using a high resolution aerosol mass spectrometer @article{d65b285d5eb94efe9d1f10733df02a6e, title = "Measurements of particulate methanesulfonic acid above the remote Arctic Ocean using a high resolution aerosol mass spectrometer", abstract = "Methanesulfonic acid (MSA) is an important product from the oxidation of dimethyl sulfide (DMS), and thus is often used as a tracer for marine biogenic sources and secondary organic aerosol. MSA also contributes to aerosol mass and potentially to the formation of cloud condensation nuclei and new particles. However, measurements of MSA at high temporal resolution in the remote Arctic are scarce, which limits our understanding of its formation, climate change impact and regional transport. Here, we applied a validated quantification method to determine the mass concentration of MSA and non-sea salt sulfate (nss-SO4) in PM2.5 in the marine boundary layer, using a high resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS) during a research cruise to the Arctic and North Atlantic Ocean, between 55 °N and 68 °N (26th May to June 23, 2022). With this method, the concentrations of MSA in the remote Arctic marine boundary layer were determined for the first time. Results show that the average MSA concentration was 0.025 ± 0.03 μg m−3, ranging from <0.01 to 0.32 μg m−3. The lowest MSA level was found towards the northern leg of the cruise (near Sisimut (67 °N)) with air masses from sea ice over the northern polar region, and the highest MSA concentrations were observed over the Atlantic open ocean. The diurnal cycles of gas MSA, particulate MSA and nss-SO4 peaked in the afternoon, about one hour later than that of peak of solar radiation, which suggests that photochemical process is an important mechanism for the conversion of DMS into MSA above the remote ocean. The mass ratio of MSA to nss-SO4 (MSA/nss-SO4) presents a temperature dependence, which indicates that the addition branching pathway favors MSA formation, while thermal decay of intermediate radicals could be a possible pathway for sulfate formation. Finally, we found that the MSA/nss-SO4 ratio is around 0.22-0.25 in the remote northern marine atmosphere.", keywords = "HR-ToF-AMS, Marine aerosol, MSA, Oxidation path, Reference MSA/nss-SO value", author = "Yangmei Zhang and Junying Sun and Xiaojing Shen and Chandani, \{Vipul Lal\} and Mao Du and Congbo Song and Yuqing Dai and Guoyuan Hu and Mingxi Yang and Tilstone, \{Gavin H.\} and Tom Jordan and Giorgio Dall'Olmo and Quan Liu and Eiko Nemitz and Anna Callaghan and James Brean and Roberto Sommariva and David Beddows and Ben Langford and William Bloss and William Acton and Roy Harrison and Manuel Dall'Osto and Zongbo Shi", note = "Publisher Copyright: {\textcopyright} 2024", year = "2024", month = aug, day = "15", doi = "10.1016/j.atmosenv.2024.120538", language = "English", volume = "331", journal = "Atmospheric Environment", issn = "1352-2310", publisher = "Elsevier", } . Atmospheric Environment.

Road Traffic Emissions Lead to Much Enhanced New Particle Formation through Increased Growth Rates @article{65c29927e9fd40a5beb1e6a4c0ada193, title = "Road Traffic Emissions Lead to Much Enhanced New Particle Formation through Increased Growth Rates", abstract = "New particle formation (NPF) is a major source of atmospheric aerosol particles, including cloud condensation nuclei (CCN), by number globally. Previous research has highlighted that NPF is less frequent but more intense at roadsides compared to urban background. Here, we closely examine NPF at both background and roadside sites in urban Central Europe. We show that the concentration of oxygenated organic molecules (OOMs) is greater at the roadside, and the condensation of OOMs along with sulfuric acid onto new particles is sufficient to explain the growth at both sites. We identify a hitherto unreported traffic-related OOM source contributing 29\% and 16\% to total OOMs at the roadside and background, respectively. Critically, this hitherto undiscovered OOM source is an essential component of urban NPF. Without their contribution to growth rates and the subsequent enhancements to particle survival, the number of >50 nm particles produced by NPF would be reduced by a factor of 21 at the roadside site. Reductions to hydrocarbon emissions from road traffic may thereby reduce particle numbers and CCN counts.", author = "James Brean and Alex Rowell and Beddows, \{David C S\} and Kay Weinhold and Peter Mettke and Maik Merkel and Thomas Tuch and Matti Rissanen and Maso, \{Miikka Dal\} and Avinash Kumar and Shawon Barua and Siddharth Iyer and Alexandra Karppinen and Alfred Wiedensohler and Zongbo Shi and Harrison, \{Roy M\}", year = "2024", month = jun, day = "8", doi = "10.1021/acs.est.3c10526", language = "English", journal = "Environmental Science and Technology", issn = "0013-936X", publisher = "American Chemical Society", } . Environmental Science and Technology.

Direct Measurements of Covalently Bonded Sulfuric Anhydrides from Gas-Phase Reactions of SO3 with Acids under Ambient Conditions @article{ba4fa7924b104e1d9078d5c2f6361346, title = "Direct Measurements of Covalently Bonded Sulfuric Anhydrides from Gas-Phase Reactions of SO3 with Acids under Ambient Conditions", abstract = "Sulfur trioxide (SO3) is an important oxide of sulfur and a key intermediate in the formation of sulfuric acid (H2SO4, SA) in the Earth{\textquoteright}s atmosphere. This conversion to SA occurs rapidly due to the reaction of SO3 with a water dimer. However, gas-phase SO3 has been measured directly at concentrations that are comparable to that of SA under polluted mega-city conditions, indicating gaps in our current understanding of the sources and fates of SO3. Its reaction with atmospheric acids could be one such fate that can have significant implications for atmospheric chemistry. In the present investigation, laboratory experiments were conducted in a flow reactor to generate a range of previously uncharacterized condensable sulfur-containing reaction products by reacting SO3 with a set of atmospherically relevant inorganic and organic acids at room temperature and atmospheric pressure. Specifically, key inorganic acids known to be responsible for most ambient new particle formation events, iodic acid (HIO3, IA) and SA, are observed to react promptly with SO3 to form iodic sulfuric anhydride (IO3SO3H, ISA) and disulfuric acid (H2S2O7, DSA). Carboxylic sulfuric anhydrides (CSAs) were observed to form by the reaction of SO3 with C2 and C3 monocarboxylic (acetic and propanoic acid) and dicarboxylic (oxalic and malonic acid)-carboxylic acids. The formed products were detected by a nitrate-ion-based chemical ionization atmospheric pressure interface time-of-flight mass spectrometer (NO3--CI-APi-TOF; NO3--CIMS). Quantum chemical methods were used to compute the relevant SO3 reaction rate coefficients, probe the reaction mechanisms, and model the ionization chemistry inherent in the detection of the products by NO3--CIMS. Additionally, we use NO3--CIMS ambient data to report that significant concentrations of SO3 and its acid anhydride reaction products are present under polluted, marine and polar, and volcanic plume conditions. Considering that these regions are rich in the acid precursors studied here, the reported reactions need to be accounted for in the modeling of atmospheric new particle formation.", author = "Avinash Kumar and Siddharth Iyer and Shawon Barua and James Brean and Emin Besic and Prasenjit Seal and Manuel Dall{\textquoteright}Osto and Beddows, \{David C.S.\} and Nina Sarnela and Tuija Jokinen and Mikko Sipil{\"a} and Harrison, \{Roy M.\} and Matti Rissanen", note = "Publisher Copyright: {\textcopyright} 2024 The Authors. Published by American Chemical Society.", year = "2024", month = jun, day = "5", doi = "10.1021/jacs.4c04531", language = "English", volume = "146", pages = "15562--15575", journal = "Journal of the American Chemical Society", issn = "0002-7863", publisher = "American Chemical Society", number = "22", } . Journal of the American Chemical Society.

Estimates of Future New Particle Formation under Different Emission Scenarios in Beijing @article{e08b5ea7cbe344db90de42751b337f34, title = "Estimates of Future New Particle Formation under Different Emission Scenarios in Beijing", abstract = "New particle formation (NPF) is a leading source of particulate matter by number and a contributor to particle mass during haze events. Reductions in emissions of air pollutants, many of which are NPF precursors, are expected in the move toward carbon neutrality or net-zero. Expected changes to pollutant emissions are used to investigate future changes to NPF processes, in comparison to a simulation of current conditions. The projected changes to SO2 emissions are key in changing future NPF number, with different scenarios producing either a doubling or near total reduction in sulfuric acid-amine particle formation rates. Particle growth rates are projected to change little in all but the strictest emission control scenarios. These changes will reduce the particle mass arising by NPF substantially, thus showing a further cobenefit of net-zero policies. Major uncertainties remain in future NPF including the volatility of oxygenated organic molecules resulting from changes to NOx and amine emissions.", keywords = "NPF, nucleation, growth, aerosols, net-zero, China, Anthropogenic Impacts on the Atmosphere, Article", author = "James Brean and Alex Rowell and David Beddows and Zongbo Shi and Roy Harrison", note = "Funding Information: This study was funded by the UK Natural Environment Research Council (grant number 2021GRIP02COP-AQ, R.M.H. and Z.S.). Publisher Copyright: {\textcopyright} 2023 The Authors. Published by American Chemical Society.", year = "2023", month = mar, day = "28", doi = "10.1021/acs.est.2c08348", language = "English", volume = "57", pages = "4741--4750", journal = "Environmental Science and Technology", issn = "0013-936X", publisher = "American Chemical Society", number = "12", } . Environmental Science and Technology.

Collective geographical ecoregions and precursor sources driving Arctic new particle formation @article{849b936de32f4f4c9fb1589ed6da8006, title = "Collective geographical ecoregions and precursor sources driving Arctic new particle formation", abstract = "The Arctic is a rapidly changing ecosystem, with complex ice-ocean-atmosphere feedbacks. An important process is new particle formation (NPF), from gas-phase precursors, which provides a climate forcing effect. NPF has been studied comprehensively at different sites in the Arctic, ranging from those in the High Arctic and those at Svalbard to those in the continental Arctic, but no harmonised analysis has been performed on all sites simultaneously, with no calculations of key NPF parameters available for some sites. Here, we analyse the formation and growth of new particles from six long-term ground-based stations in the Arctic (Alert, Villum, Tiksi, Zeppelin Mountain, Gruvebadet, and Utqia{\"A}¡vik). Our analysis of particle formation and growth rates in addition to back-trajectory analysis shows a summertime maxima in the frequency of NPF and particle formation rate at all sites, although the mean frequency and particle formation rates themselves vary greatly between sites, with the highest at Svalbard and lowest in the High Arctic. The summertime growth rate, condensational sinks, and vapour source rates show a slight bias towards the southernmost sites, with vapour source rates varying by around an order of magnitude between the northernmost and southernmost sites. Air masses back-trajectories during NPF at these northernmost sites are associated with large areas of sea ice and snow, whereas events at Svalbard are associated with more sea ice and ocean regions. Events at the southernmost sites are associated with large areas of land and sea ice. These results emphasise how understanding the geographical variation in surface type across the Arctic is key to understanding secondary aerosol sources and providing a harmonised analysis of NPF across the Arctic.", author = "James Brean and Beddows, \{David C.S.\} and Harrison, \{Roy M.\} and Congbo Song and Peter Tunved and Johan Str{\"o}m and Radovan Krejci and Eyal Freud and Andreas Massling and Henrik Skov and Eija Asmi and Angelo Lupi and Manuel Dall'osto", note = "Funding Information: This research has been supported by the Ministerio de Econom{\'i}a y Competitividad (grant nos. CTM2017-89117-R, CGL2013-49020-R, and RYC-2012-11922), the Natural Environment Research Council (grant no. NE/S00579X/1), and the National Centre for Atmospheric Science funded by the Natural Environment Research Council.We acknowledge support of the publication fee by the CSIC Open Access Publication Support Initiative through its Unit of Information Resources for Research (URICI). The aerosol and meteorological data for Utqiaġvik and Tiksi were downloaded from the International Arctic Systems for Observing the Atmosphere ( https://www.iasoa.org , last access: 21 August 2021) consortium website. For the Alert observations, we are grateful to the Canadian Department of National Defence, Andrew Platt, Sangeeta Sharma, Desiree Toom, Dan Veber, and the Alert operators. Funding from the European Union's Horizon 2020 programmes of ACTRIS (grant no. 654109) and INTAROS (project no. 727890) are acknowledged (Eija Asmi). Observations at Zeppelin Mountain observatory were supported by Swedish Environmental Protection agency (Naturv{\aa}rdsverket) and by the ACAS project funded by Knut and Alice Wallenberg Foundation. The study has been supported by the UK Natural Environment Research Council (SEANA; grant no. NE/S00579X/1), the Spanish Ministry of Economy through projects BIOeNUC (grant no. CGL2013–49020-R) and PI-ICE (grant no. CTM2017–89117-R) and the Ram{\'o}n y Cajal fellowship (grant no. RYC-2012-11922). The authors also acknowledge financial support (to David C. S. Beddows) from the National Centre for Atmospheric Science (NCAS; grant no. R8/H12/83/011), funded by UK Natural Environment Research Council. Finally, the authors from Aarhus University have been financially supported by the Danish Environmental Protection Agency and Danish Ministry for Climate Energy and Utilities via the MIKA/DANCEA funds for Environmental Support to the Arctic Region. As stressed in Freud et al. (2017), we would also like to express our appreciation and gratitude for the work and effort of all the scientists and engineers involved in setting up and maintaining the Arctic aerosol sites. The figures were created using the R software (R Core Team, 2022). Publisher Copyright: {\textcopyright} Copyright: ", year = "2023", month = feb, day = "14", doi = "10.5194/acp-23-2183-2023", language = "English", volume = "23", pages = "2183--2198", journal = "Atmospheric Chemistry and Physics", issn = "1680-7316", publisher = "Copernicus Publications", number = "3", } . Atmospheric Chemistry and Physics.

James Brean, Alfred W. Mayhew, Ben H. Lee, Joel A. Thornton, Thomas J. Bannan, James R. Hopkins, James D. Lee, Beth S. Nelson, Carl Percival, Andrew R. Rickard, et al. (2022). Evaluation of isoprene nitrate chemistry in detailed chemical mechanisms . Atmospheric Chemistry and Physics.

Understanding sources and drivers of size-resolved aerosol in the high Arctic islands of Svalbard using a receptor model coupled with machine learning @article{6cfbfdaa4455470188d26cd73f9540f7, title = "Understanding sources and drivers of size-resolved aerosol in the high Arctic islands of Svalbard using a receptor model coupled with machine learning", abstract = "Atmospheric aerosols are important drivers of Arctic climate change through aerosol-cloud-climate interactions. However, large uncertainties remain on the sources and processes controlling particle numbers in both fine and coarse modes. Here, we applied a receptor model and an explainable machine learning technique to understand the sources and drivers of particle numbers from 10 nm to 20 μm in Svalbard. Nucleation, biogenic, secondary, anthropogenic, mineral dust, sea salt and blowing snow aerosols and their major environmental drivers were identified. Our results show that the monthly variations in particles are highly size/source dependent and regulated by meteorology. Secondary and nucleation aerosols are the largest contributors to potential cloud condensation nuclei (CCN, particle number with a diameter larger than 40 nm as a proxy) in the Arctic. Nonlinear responses to temperature were found for biogenic, local dust particles and potential CCN, highlighting the importance of melting sea ice and snow. These results indicate that the aerosol factors will respond to rapid Arctic warming differently and in a nonlinear fashion.", keywords = "Arctic, machine learning, meteorology, particle number concentration, positive matrix factorization, source apportionment", author = "Congbo Song and Silvia Becagli and Beddows, \{David C S\} and James Brean and Jo Browse and Qili Dai and Manuel Dall'Osto and Valerio Ferracci and Harrison, \{Roy M\} and Neil Harris and Weijun Li and Jones, \{Anna E\} and Am{\'e}lie Kirchg{\"a}{\ss}ner and Kramawijaya, \{Agung Ghani\} and Alexander Kurganskiy and Angelo Lupi and Mauro Mazzola and Mirko Severi and Rita Traversi and Zongbo Shi", note = "Funding Information: This research was supported by the Natural Environment Research Council (grant no. NE/S00579X/1) and endorsed by the Surface Ocean-Lower Atmosphere Study (SOLAS). The authors acknowledge the staff of the Arctic Station Dirigibile Italia of the National Research Council of Italy for their support in measurements at the GVB station. The authors acknowledge the NOAA Air Resources Laboratory (ARL) for providing the HYSPLIT model used to analyze the back trajectories. Publisher Copyright: {\textcopyright} 2022 The Authors. Published by American Chemical Society.", year = "2022", month = aug, day = "16", doi = "10.1021/acs.est.1c07796", language = "English", volume = "56", pages = "11189--11198", journal = "Environmental Science and Technology", issn = "0013-936X", publisher = "American Chemical Society", number = "16", } . Environmental Science and Technology.

Measurement report @article{e071a688d6764528b3380c35ce0fcb72, title = "Measurement report: interpretation of wide-range particulate matter size distributions in Delhi", abstract = "Delhi is one of the world's most polluted cities, with very high concentrations of airborne particulate matter. However, little is known about the factors controlling the characteristics of wide-range particle number size distributions. Here, new measurements are reported from three field campaigns conducted in winter and pre-monsoon and post-monsoon seasons at the Indian Institute of Technology campus in the south of the city. Particle number size distributions were measured simultaneously, using a scanning mobility particle sizer and a GRIMM optical particle monitor, covering 15 nm to >10 μm diameter. The merged, wide-range size distributions were categorized into the following five size ranges: nucleation (15-20 nm), Aitken (20-100 nm), accumulation (100 nm-1 μm), large fine (1-2.5 μm), and coarse (2.5-10 μm) particles. The ultrafine fraction (15-100 nm) accounts for about 52 \% of all particles by number (PN10 is the total particle number from 15 nm to 10 μm) but just 1 \% by PM10 volume (PV10 is the total particle volume from 15 nm to 10 μm). The measured size distributions are markedly coarser than most from other parts of the world but are consistent with earlier cascade impactor data from Delhi. Our results suggest substantial aerosol processing by coagulation, condensation, and water uptake in the heavily polluted atmosphere, which takes place mostly at nighttime and in the morning hours. Total number concentrations are highest in winter, but the mode of the distribution is largest in the post-monsoon (autumn) season. The accumulation mode particles dominate the particle volume in autumn and winter, while the coarse mode dominates in summer. Polar plots show a huge variation between both size fractions in the same season and between seasons for the same size fraction. The diurnal pattern of particle numbers is strongly reflective of a road traffic influence upon concentrations, especially in autumn and winter, although other sources, such as cooking and domestic heating, may influence the evening peak. There is a clear influence of diesel traffic at nighttime, when it is permitted to enter the city, and also indications in the size distribution data of a mode < 15 nm, which is probably attributable to CNG/LPG vehicles. New particle formation appears to be infrequent and is, in this dataset, limited to 1 d in the summer campaign. Our results reveal that the very high emissions of airborne particles in Delhi, particularly from traffic, determine the variation in particle number size distributions. ", author = "{\c S}ahin, \{{\"U}lk{\"u} Alver\} and Harrison, \{Roy M.\} and Alam, \{Mohammed S.\} and Beddows, \{David C.S.\} and Dimitrios Bousiotis and Zongbo Shi and Crilley, \{Leigh R.\} and William Bloss and James Brean and Isha Khanna and Rulan Verma", note = "Funding Information: Financial support. We are thankful to the Scientific and Technical Research Council of Turkey (TUBITAK; grant no. 1059B191801445), who supported the work of {\"U}lk{\"u} Alver S¸ahin for this ASAP project. This research has been supported by the Natural Environment Research Council (grant no. NE/P016499/1).", year = "2022", month = apr, day = "25", doi = "10.5194/acp-22-5415-2022", language = "English", volume = "22", pages = "5415--5433", journal = "Atmospheric Chemistry and Physics", issn = "1680-7316", publisher = "Copernicus Publications", number = "8", } . Atmospheric Chemistry and Physics.

James Brean, &#220;lk&#252; Alver Şahin, Roy M. Harrison, Mohammed S. Alam, David C. S. Beddows, Dimitrios Bousiotis, Zongbo Shi, Leigh R. Crilley, William Bloss, Isha Khanna, et al. (2022). Measurement report: Interpretation of wide-range particulate matter size distributions in Delhi . Atmospheric Chemistry and Physics.

Differentiation of coarse-mode anthropogenic, marine and dust particles in the high Arctic islands of Svalbard @article{0485d83397f04536a65d09558dce700c, title = "Differentiation of coarse-mode anthropogenic, marine and dust particles in the high Arctic islands of Svalbard", abstract = "Understanding aerosol–cloud–climate interactions in the Arctic is key to predicting the climate in this rapidly changing region. Whilst many studies have focused on submicrometer aerosol (diameter less than 1 μm), relatively little is known about the supermicrometer aerosol (diameter above 1 μm). Here, we present a cluster analysis of multiyear (2015–2019) aerodynamic volume size distributions, with diameter ranging from 0.5 to 20 μm, measured continuously at the Gruvebadet Observatory in the Svalbard archipelago. Together with aerosol chemical composition data from several online and offline measurements, we apportioned the occurrence of the coarse-mode aerosols during the study period (mainly from March to October) to anthropogenic (two sources, 27\%) and natural (three sources, 73\%) origins. Specifically, two clusters are related to Arctic haze with high levels of black carbon, sulfate and accumulation mode (0.1–1 μm) aerosol. The first cluster (9\%) is attributed to ammonium sulfate-rich Arctic haze particles, whereas the second one (18\%) is attributed to larger-mode aerosol mixed with sea salt. The three natural aerosol clusters were openocean sea spray aerosol (3 \%), mineral dust (7\%) and an unidentified source of sea spray-related aerosol (32\%). The results suggest that sea-spray-related aerosol in polar regions may be more complex than previously thought due to shortand long-distance origins and mixtures with Arctic haze, biogenic and likely blowing snow aerosols. Studying supermicrometer natural aerosol in the Arctic is imperative for understanding the impacts of changing natural processes on Arctic aerosol.", author = "Congbo Song and Manuel Dall{\textquoteright}Osto and Angelo Lupi and Mauro Mazzola and Rita Traversi and Silvia Becagli and Stefania Gilardoni and Stergios Vratolis and \{Espen Yttri\}, Karl and David Beddows and Julia Schmale and James Brean and Kramawijaya, \{Agung Ghani\} and Roy Harrison and Zongbo Shi", year = "2021", month = jul, day = "28", doi = "10.5194/acp-21-11317-2021", language = "English", volume = "21", pages = "11317–11335", journal = "Atmospheric Chemistry and Physics", issn = "1680-7316", publisher = "Copernicus Publications", number = "14", } . Atmospheric Chemistry and Physics.

Open ocean and coastal new particle formation from sulfuric acid and amines around the Antarctic Peninsula @article{214f7f0d5bb448d9b63c164f8c79d7c5, title = "Open ocean and coastal new particle formation from sulfuric acid and amines around the Antarctic Peninsula", abstract = "New particle formation is globally one of the major sources of aerosol particles and cloud condensation nuclei. As primary emissions are a minor contributor to particle concentrations, secondary new particle formation processes are probably key in determining Antarctic aerosol number concentrations. However, our knowledge of new particle formation and its mechanisms in Antarctica is very limited. Here we study summertime open ocean and coastal new particle formation in the Antarctic Peninsula region based on both ship and station measurements. The rates of particle formation relative to sulfuric acid concentrations, as well as the sulfuric acid dimer-to-monomer ratios, were similar to those seen for sulfuric acid–dimethylamine–water nucleation. Numerous sulfuric acid–amine peaks were identified during new particle formation events, providing evidence that alkylamines were the bases that facilitated sulfuric acid nucleation. Most new particle formation events occurred in air masses arriving from the ice-covered Weddell Sea and its marginal ice zone, which are an important source of volatile sulfur and alkylamines. This nucleation mechanism is more efficient than the ion-induced sulfuric acid–ammonia pathway previously observed in Antarctica, and one that can occur rapidly under neutral conditions. This hitherto overlooked pathway to biologically driven aerosol formation should be considered for estimating aerosol and cloud condensation nuclei numbers in ocean–sea ice–aerosols–climate feedback models.", author = "James Brean and Manuel Dall{\textquoteright}Osto and Rafel Sim{\'o} and Zongbo Shi and Beddows, \{David C.S.\} and Harrison, \{Roy M.\}", note = "Funding Information: We thank the Spanish Armada, and particularly the captains and crew of the BIO A-33 Hesperides, for their invaluable collaboration. We are also indebted to the UTM, and especially M. Ojeda, for logistic and technical support on the Antarctic Spanish BAE JC1. We also thank A. Sotomayor for help with mapping. This study was funded by the Spanish Ministry of Economy (grant number PI‐ICE‐CTM 2017–89117‐R and RYC-2012-11922, both awarded to M.D.{\textquoteright}O.). This work was also supported by the National Centre for Atmospheric Science funded by the UK Natural Environment Research Council (grant number R8/H12/83/011 to R.M.H. and D.C.S.B., which also supported a studentship (ncasstu009) for J.B.). Publisher Copyright: {\textcopyright} 2021, The Author(s), under exclusive licence to Springer Nature Limited.", year = "2021", month = jun, doi = "10.1038/s41561-021-00751-y", language = "English", volume = "14", pages = "383--388", journal = "Nature Geoscience", issn = "1752-0894", publisher = "Nature Publishing Group", number = "6", } . Nature Geoscience.

The effect of meteorological conditions and atmospheric composition in the occurrence and development of new particle formation (NPF) events in Europe @article{cfc5d67a2dfc43a8904e44bf712b92a7, title = "The effect of meteorological conditions and atmospheric composition in the occurrence and development of new particle formation (NPF) events in Europe", abstract = "Although new particle formation (NPF) events have been studied extensively for some decades, the mechanisms that drive their occurrence and development are yet to be fully elucidated. Laboratory studies have done much to elucidate the molecular processes involved in nucleation, but this knowledge has yet to be conclusively linked to NPF events in the atmosphere. There is great difficulty in successful application of the results from laboratory studies to real atmospheric conditions due to the diversity of atmospheric conditions and observations found, as NPF events occur almost everywhere in the world without always following a clearly defined trend of frequency, seasonality, atmospheric conditions, or event development. The present study seeks common features in nucleation events by applying a binned linear regression over an extensive dataset from 16 sites of various types (combined dataset of 85 years from rural and urban backgrounds as well as roadside sites) in Europe. At most sites, a clear positive relation with the frequency of NPF events is found between the solar radiation intensity (up to R2=0.98), temperature (up to R2=0.98), and atmospheric pressure (up to R2=0.97), while relative humidity (RH) presents a negative relation (up to R2=0.95) with NPF event frequency, though exceptions were found among the sites for all the variables studied. Wind speed presents a less consistent relationship, which appears to be heavily affected by local conditions. While some meteorological variables (such as the solar radiation intensity and RH) appear to have a crucial effect on the occurrence and characteristics of NPF events, especially at rural sites, it appears that their role becomes less marked at higher average values. The analysis of chemical composition data presents interesting results. Concentrations of almost all chemical compounds studied (apart from O3) and the condensation sink (CS) have a negative relationship with NPF event frequency, though areas with higher average concentrations of SO2 had higher NPF event frequency. Particulate organic carbon (OC), volatile organic compounds (VOCs), and particulate-phase sulfate consistently had a positive relation with the growth rate of the newly formed particles. As with some meteorological variables, it appears that at increased concentrations of pollutants or the CS, their influence upon NPF frequency is reduced.", author = "Dimitrios Bousiotis and James Brean and Pope, \{Francis D.\} and Manuel Dall'osto and Xavier Querol and Andr{\'e}s Alastuey and Noemi Perez and Tuukka Pet{\"a}j{\"a} and Andreas Massling and N{\o}jgaard, \{Jacob Klen{\o}\} and Claus Nordstr{\o}m and Giorgos Kouvarakis and Stergios Vratolis and Konstantinos Eleftheriadis and Niemi, \{Jarkko V.\} and Harri Portin and Alfred Wiedensohler and Kay Weinhold and Maik Merkel and Thomas Tuch and Harrison, \{Roy M.\}", note = "Funding Information: Financial support. This research has been supported by the Natural", year = "2021", month = mar, day = "4", doi = "10.5194/acp-21-3345-2021", language = "English", volume = "21", pages = "3345--3370", journal = "Atmospheric Chemistry and Physics", issn = "1680-7316", publisher = "Copernicus Publications", number = "5", } . Atmospheric Chemistry and Physics.

Using highly time-resolved online mass spectrometry to examine biogenic and anthropogenic contributions to organic aerosol in Beijing @article{c63f552fce4e471fb4cae1b213a7a101, title = "Using highly time-resolved online mass spectrometry to examine biogenic and anthropogenic contributions to organic aerosol in Beijing", abstract = "Organic aerosols, a major constituent of fine particulate mass in megacities, can be directly emitted or formed from secondary processing of biogenic and anthropogenic volatile organic compound emissions. The complexity of volatile organic compound emission sources, speciation and oxidation pathways leads to uncertainties in the key sources and chemistry leading to formation of organic aerosol in urban areas. Historically, online measurements of organic aerosol composition have been unable to resolve specific markers of volatile organic compound oxidation, while offline analysis of markers focus on a small proportion of organic aerosol and lack the time resolution to carry out detailed statistical analysis required to study the dynamic changes in aerosol sources and chemistry. Here we use data collected as part of the joint UK-China Air Pollution and Human Health (APHH-Beijing) collaboration during a field campaign in urban Beijing in the summer of 2017 alongside laboratory measurements of secondary organic aerosol from oxidation of key aromatic precursors (1,3,5-Trimethyl benzene, 1,2,4-Trimethyl benzene, propyl benzene, isopropyl benzene and 1-methyl naphthalene) to study the anthropogenic and biogenic contributions to organic aerosol. For the first time in Beijing, this study applies positive matrix factorisation to online measurements of organic aerosol composition from a time-of-flight iodide chemical ionisation mass spectrometer fitted with a filter inlet for gases and aerosols (FIGAERO-ToF-I-CIMS). This approach identifies the real-Time variations in sources and oxidation processes influencing aerosol composition at a near-molecular level. We identify eight factors with distinct temporal variability, highlighting episodic differences in OA composition attributed to regional influences and in situ formation. These have average carbon numbers ranging from C5-C9 and can be associated with oxidation of anthropogenic aromatic hydrocarbons alongside biogenic emissions of isoprene, α-pinene and sesquiterpenes. This journal is ", author = "Archit Mehra and Manjula Canagaratna and Bannan, \{Thomas J.\} and Worrall, \{Stephen D.\} and Asan Bacak and Michael Priestley and Dantong Liu and Jian Zhao and Weiqi Xu and Yele Sun and Hamilton, \{Jacqueline F.\} and Squires, \{Freya A.\} and James Lee and Bryant, \{Daniel J.\} and Hopkins, \{James R.\} and Atallah Elzein and Budisulistiorini, \{Sri Hapsari\} and Xi Cheng and Qi Chen and Yuwei Wang and Lin Wang and Harald Stark and Krechmer, \{Jordan E.\} and James Brean and Eloise Slater and Lisa Whalley and Dwayne Heard and Bin Ouyang and Acton, \{W. Joe F.\} and Hewitt, \{C. Nicholas\} and Xinming Wang and Pingqing Fu and John Jayne and Douglas Worsnop and James Allan and Carl Percival and Hugh Coe", note = "Publisher Copyright: {\textcopyright} The Royal Society of Chemistry.", year = "2021", month = mar, day = "1", doi = "10.1039/d0fd00080a", language = "English", volume = "226", pages = "382--408", journal = "Faraday Discussions", issn = "1359-6640", publisher = "Royal Society of Chemistry", } . Faraday Discussions.

Mehra, A., Canagaratna, M., Bannan, T.J., Worrall, S.D., Bacak, A., Priestley, M., Liu, D., Zhao, J., Xu, W., Sun, Y., et al.(2021). Using highly time-resolved online mass spectrometry to examine biogenic and anthropogenic contributions to organic aerosol in Beijing . Faraday Discussions. 226. Microsoft.AspNetCore.Mvc.Localization.LocalizedHtmlString 382-408.

Brean, J., Dall’Osto, M., Sim&#243;, R., Shi, Z., Beddows, D.C.S., Harrison, R.M.(2021). Open ocean and coastal new particle formation from sulfuric acid and amines around the Antarctic Peninsula . Nature Geoscience. 14. (6). Microsoft.AspNetCore.Mvc.Localization.LocalizedHtmlString 383-388.

Bousiotis, D., Brean, J., Pope, F.D., Dall&#39;Osto, M., Querol, X., Alastuey, A., Perez, N., Pet&#228;j&#228;, T., Massling, A., Klen&#248; N&#248;jgaard, J., et al.(2021). The effect of meteorological conditions and atmospheric composition in the occurrence and development of new particle formation (NPF) events in Europe . Atmospheric Chemistry and Physics. 21. (5). Microsoft.AspNetCore.Mvc.Localization.LocalizedHtmlString 3345-3370.

James Brean, Archit Mehra, Manjula Canagaratna, Thomas J. Bannan, Stephen D. Worrall, Asan Bacak, Michael Priestley, Dantong Liu, Jian Zhao, Weiqi Xu, et al.(2021). Using highly time-resolved online mass spectrometry to examine biogenic and anthropogenic contributions to organic aerosol in Beijing . Faraday Discussions. Royal Society of Chemistry ({RSC})

Song, C., Dallosto, M., Lupi, A., Mazzola, M., Traversi, R., Becagli, S., Gilardoni, S., Vratolis, S., Yttri, K.E., Beddows, D.C.S., et al.(2021). Differentiation of coarse-mode anthropogenic, marine and dust particles in the High Arctic islands of Svalbard . Atmospheric Chemistry and Physics. 21. (14). Microsoft.AspNetCore.Mvc.Localization.LocalizedHtmlString 11317-11335.

Alam, M.S., Bloss, W., Brean, J., Brimblecombe, P., Chan, C., Chen, Y., Coe, H., Fu, P., Gani, S., Hamilton, J., et al.(2021). General discussion: Aerosol formation and growth; VOC sources and secondary organic aerosols . Faraday Discussions. 226. Microsoft.AspNetCore.Mvc.Localization.LocalizedHtmlString 479-501.

Molecular insights into new particle formation in Barcelona, Spain @article{d1e5ba32ef9e4eb190164afba2a244f9, title = "Molecular insights into new particle formation in Barcelona, Spain", abstract = "Atmospheric aerosols contribute some of the greatest uncertainties to estimates of global radiative forcing and have significant effects on human health. New particle formation (NPF) is the process by which new aerosols of sub-2\&thinsp;nm diameter form from gas-phase precursors and contributes significantly to particle numbers in the atmosphere, accounting for approximately 50\&thinsp;\% of cloud condensation nuclei globally. Here, we study summertime NPF in urban Barcelona in north-eastern Spain utilising particle counting instruments down to 1.9\&thinsp;nm and a Nitrate Chemical Ionisation Atmospheric Pressure interface Time of Flight Mass Spectrometer (CI-APi-ToF). The rate of formation of new particles is seen to increase linearly with sulfuric acid concentration, although particle formation rates fall short of chamber studies of H2SO4-DMA-H2O while exceeding those of H2SO4-BioOxOrg-H2O nucleation, although a role of highly oxygenated molecules (HOMs) cannot be ruled out. The sulfuric acid dimer\&thinsp;:\&thinsp;monomer ratio is significantly lower than that seen in experiments involving sulfuric acid and dimethylamine (DMA) in chambers, indicating that stabilisation of sulfuric acid clusters by bases is weaker in this dataset than in chambers, either due to rapid evaporation due to high summertime temperatures or limited pools of stabilising amines. Such a mechanism cannot be verified in these data, as no higher-order H2SO4-amine clusters nor H2SO4-HOM clusters were measured. The high concentrations of HOMs arise from isoprene, alkylbenzene, monoterpene and polycyclic aromatic hydrocarbon (PAH) oxidation, with alkylbenzenes providing greater concentrations of HOMs due to significant local sources. The concentration of these HOMs shows a dependence on temperature. The organic compounds measured primarily fall into the semivolatile organic compound (SVOC) volatility class arising from alkylbenzene and isoprene oxidation. Low-volatility organic compounds (LVOCs) largely arise from oxidation of alkylbenzenes, PAHs and monoterpenes, whereas extremely low-volatility organic compounds (ELVOCs) arise from primarily PAH and monoterpene oxidation. New particle formation without growth past 10\&thinsp;nm is also observed, and on these days oxygenated organic concentrations are lower than on days with growth by a factor of 1.6, and thus high concentrations of low-volatility oxygenated organics which primarily derive from traffic-emitted volatile organic compounds (VOCs) appear to be a necessary condition for the growth of newly formed particles in Barcelona. These results are consistent with prior observations of new particle formation from sulfuric acid-amine reactions in both chambers and the real atmosphere and are likely representative of the urban background of many European Mediterranean cities. A role for HOMs in the nucleation process cannot be confirmed or ruled out, and there is strong circumstantial evidence of the participation of HOMs across multiple volatility classes in particle growth.", author = "James Brean and Beddows, \{David C.S.\} and Zongbo Shi and Brice Temime-Roussel and Nicolas Marchand and Xavier Querol and Andres Alastuey and Minguillon, \{Maria Cruz\} and Harrison, \{Roy M.\}", year = "2020", month = aug, day = "27", doi = "10.5194/acp-20-10029-2020", language = "English", volume = "20", pages = "10029--10045", journal = "Atmospheric Chemistry and Physics", issn = "1680-7316", publisher = "Copernicus Publications", number = "16", } . Atmospheric Chemistry and Physics.

James Brean, David C. S. Beddows, Zongbo Shi, Brice Temime-Roussel, Nicolas Marchand, Xavier Querol, Andr&#233;s Alastuey, Mar&#237;a Cruz Minguill&#243;n, Roy M. Harrison(2020). Molecular insights into new particle formation in Barcelona, Spain . Atmospheric Chemistry and Physics. 20. (16). Microsoft.AspNetCore.Mvc.Localization.LocalizedHtmlString 10029--10045. Copernicus {GmbH}

Brean, J., Beddows, D.C.S., Shi, Z., Temime-Roussel, B., Marchand, N., Querol, X., Alastuey, A., Minguillon, M.C., Harrison, R.M.(2020). Molecular insights into new particle formation in Barcelona, Spain . Atmospheric Chemistry and Physics. 20. (16). Microsoft.AspNetCore.Mvc.Localization.LocalizedHtmlString 10029-10045.

Observations of highly oxidized molecules and particle nucleation in the atmosphere of Beijing @article{808cf3e39623437795639d1547487af0, title = "Observations of highly oxidized molecules and particle nucleation in the atmosphere of Beijing", abstract = "Particle nucleation is one of the main sources of atmospheric particulate matter by number, with new particles having great relevance for human health and climate. Highly oxidized multifunctional organic molecules (HOMs) have been recently identified as key constituents in the growth and, sometimes, in initial formation of new particles. While there have been many studies of HOMs in atmospheric chambers, flow tubes, and clean environments, analyses of data from polluted environments are scarce. Here, measurements of HOMs and particle size distributions down to small molecular clusters are presented alongside volatile organic compounds (VOCs) and trace-gas data from a campaign in June 2017, in Beijing. Many gas-phase HOMs have been characterized and their temporal trends and behaviours analysed in the context of new particle formation. The HOMs identified have a degree of oxidation comparable to that seen in other, cleaner, environments, likely due to an interplay between the higher temperatures facilitating rapid hydrogen abstractions and the higher concentrations of NOx and other RO2. Terminators ending the autoxidation sequence more rapidly. Our data indicate that alkylbenzenes, monoterpenes, and isoprene are important precursor VOCs for HOMs in Beijing. Many of the C5 and C10 compounds derived from isoprene and monoterpenes have a slightly greater degree of average oxidation state of carbon compared to those from other precursors. Most HOMs except for large dimers have daytime peak concentrations, indicating the importance of OH. chemistry in the formation of HOMs, as O3 tends to be lower on days with higher HOM concentrations; similarly, VOC concentrations are lower on the days with higher HOM concentrations. The daytime peaks of HOMs coincide with the growth of freshly formed new particles, and their initial formation coincides with the peak in sulfuric acid vapours, suggesting that the nucleation process is sulfuric-acid-dependent, with HOMs contributing to subsequent particle growth.", author = "James Brean and Roy Harrison and Zongbo Shi and David Beddows and Acton, \{W. Joe F.\} and Hewitt, \{C. Nicholas\} and Squires, \{Freya A.\} and James Lee", year = "2019", month = dec, day = "10", doi = "10.5194/acp-19-14933-2019", language = "English", volume = "19", pages = "14933--14947", journal = "Atmospheric Chemistry and Physics", issn = "1680-7316", publisher = "Copernicus Publications", number = "23", } . Atmospheric Chemistry and Physics.

Interpretation of particle number size distributions measured across an urban area during the FASTER campaign @article{5574bdf6cf5045e98103a50f74fbaec0, title = "Interpretation of particle number size distributions measured across an urban area during the FASTER campaign", abstract = "Particle number size distributions have been measured simultaneously by scanning mobility particle sizers (SMPSs) at five sites in central London for a 1 month campaign in January-February 2017. These measurements were accompanied by condensation particle counters (CPCs) to measure total particle number count at four of the sites and Aethalometers measuring black carbon (BC) at five sites. The spatial distribution and inter-relationships of the particle size distribution and SMPS total number counts with CPC total number counts and black carbon measurements have been analysed in detail as well as variations in the size distributions. One site (Marylebone Road) was in a street canyon with heavy traffic, one site (Westminster University) was on a rooftop adjacent to the Marylebone Road sampler, and a further sampler was located at Regent's University within a major park to the north of Marylebone Road. A fourth sampler was located nearby at 160 m above ground level on the BT tower and a fifth sampler was located 4 km to the west of the main sampling region at North Kensington. Consistent with earlier studies it was found that the mode in the size distribution had shifted to smaller sizes at the Regent's University (park) site, the mean particle shrinkage rate being 0.04 nm s-1 with slightly lower values at low wind speeds and some larger values at higher wind speeds. There was evidence of complete evaporation of the semi-volatile nucleation mode under certain conditions at the elevated BT Tower site. While the SMPS total count and black carbon showed typical traffic-dominated diurnal profiles, the CPC count data typically peaked during night-time as did CPC/BC ratios. This is thought to be due to the presence of high concentrations of small particles (2.5-15 nm diameter) probably arising from condensational growth from traffic emissions during the cooler night-time conditions. Such behaviour was most marked at the Regent's University and Westminster University sites and less so at Marylebone Road, while at the elevated BT Tower site the ratio of particle number (CPC) to black carbon peaked during the morning rush hour and not at night-time, unlike the other sites. An elevation in nucleation mode particles associated with winds from the west and WSW sector was concluded to result from emissions from London Heathrow Airport, despite a distance of 22 km from the central London sites.", author = "Harrison, \{Roy M.\} and Beddows, \{David C.S.\} and Alam, \{Mohammed S.\} and Ajit Singh and James Brean and Ruixin Xu and Simone Kotthaus and Sue Grimmond", year = "2019", month = jan, day = "3", doi = "10.5194/acp-19-39-2019", language = "English", volume = "19", pages = "39--55", journal = "Atmospheric Chemistry and Physics", issn = "1680-7316", publisher = "Copernicus Publications", number = "1", } . Atmospheric Chemistry and Physics.

Brean, J., Harrison, R.M., Shi, Z., Beddows, D.C.S., Acton, W.J.F., Nicholas Hewitt, C., Squires, F.A., Lee, J.(2019). Observations of highly oxidized molecules and particle nucleation in the atmosphere of Beijing . Atmospheric Chemistry and Physics. 19. (23). Microsoft.AspNetCore.Mvc.Localization.LocalizedHtmlString 14933-14947.

Harrison, R.M., Beddows, D.C.S., Alam, M.S., Singh, A., Brean, J., Xu, R., Kotthaus, S., Grimmond, S.(2019). Interpretation of particle number size distributions measured across an urban area during the FASTER campaign . Atmospheric Chemistry and Physics. 19. (1). Microsoft.AspNetCore.Mvc.Localization.LocalizedHtmlString 39-55.

James Brean, Roy M. Harrison, Zongbo Shi, David C. S. Beddows, W. Joe F. Acton, C. Nicholas Hewitt, Freya A. Squires, James Lee(2019). Observations of highly oxidized molecules and particle nucleation in the atmosphere of Beijing . Atmospheric Chemistry and Physics. 19. (23). Microsoft.AspNetCore.Mvc.Localization.LocalizedHtmlString 14933--14947. Copernicus {GmbH}

OTHER

Aerosol, clouds and particles @article{21c82649b6b24305983587c32c8e1b93, title = "Aerosol, clouds and particles: general discussion", author = "Sarah Albertin and Markus Ammann and Thorsten Bartels-Rausch and James Brean and Carpenter, \{Lucy J.\} and Rohit Chikkaraddy and Chipperfield, \{Martyn P.\} and Giancarlo Ciarelli and Hugh Coe and Cyran, \{Jen{\'e}e D.\} and Barbara D'Anna and Bruno Delille and Valerio Ferracci and Frey, \{Markus M.\} and Natasha Garner and Dwayne Heard and Kanji, \{Zamin A.\} and Saewung Kim and Julia Kojoj and Alexis Lamothe and Law, \{Kathy S.\} and S{\"o}nke Maus and Claudia Mohr and Murphy, \{Jennifer G.\} and Christian Pfrang and Kerri Pratt and Tjarda Roberts and Jochen Stutz and Thomas Whale and Megan Willis and Xin Yang and Paul Zieger", year = "2025", month = jun, day = "1", doi = "10.1039/d5fd90012c", language = "English", volume = "258", pages = "171--200", journal = "Faraday Discussions", issn = "1359-6640", publisher = "Royal Society of Chemistry", } . Faraday Discussions.

Transport and chemistry @article{237bb9c9eea547e9818f5f0e4a6aeac1, title = "Transport and chemistry: general discussion", author = "Markus Ammann and James Brean and Carpenter, \{Lucy J.\} and Rohit Chikkaraddy and Chipperfield, \{Martyn P.\} and Barbara D'Anna and Valerio Ferracci and Frey, \{Markus M.\} and Heard, \{Dwayne E.\} and Heddell, \{Saffron G.\} and Alicia Hoffman and Deanna Huff and Bianca Lauster and Law, \{Kathy S.\} and Jingqiu Mao and Claudia Mohr and Murphy, \{Jennifer G.\} and Peterson, \{Peter K.\} and Pratt, \{Kerri A.\} and Roberts, \{Tjarda J.\} and Joel Savarino and Freya Squires and Jochen Stutz and Megan Willis and Xin Yang", year = "2025", month = jun, day = "1", doi = "10.1039/D5FD90013A", language = "English", volume = "258", pages = "328--356", journal = "Faraday Discussions", issn = "1359-6640", publisher = "Royal Society of Chemistry", } . Faraday Discussions.

Multiphase chemistry @article{62a35c751eb94a2cb20539ab736af4f5, title = "Multiphase chemistry: general discussion", author = "Sarah Albertin and Markus Ammann and Patrick Ayotte and Thorsten Bartels-Rausch and Hendrik Bluhm and James Brean and Natalie Brett and Brown, \{Lucy V\} and Tillmann Buttersack and Carpenter, \{Lucy J\} and Rohit Chikkaraddy and Hugh Coe and Cyran, \{Jen{\'e}e D\} and Natasha Garner and Dwayne Heard and Deanna Huff and Saewung Kim and Jingqiu Mao and Murphy, \{Jennifer G\} and Christian Pfrang and Pratt, \{Kerri A\} and Matti Rissanen and Joel Savarino and C{\'e}line Toubin and Thomas Whale and Megan Willis", year = "2025", month = jun, day = "1", doi = "10.1039/d5fd90014j", language = "English", volume = "258", pages = "419--440", journal = "Faraday Discussions", issn = "1359-6640", publisher = "Royal Society of Chemistry", } . Faraday Discussions.

Snow and ice @article{4a87d6d39bdf48d496e8c01f081b3476, title = "Snow and ice: general discussion", author = "Markus Ammann and Veronica Amoruso and Patrick Ayotte and Thorsten Bartels-Rausch and Hendrik Bluhm and James Brean and Tillmann Buttersack and Carpenter, \{Lucy J.\} and Rohit Chikkaraddy and Cyran, \{Jen{\'e}e D.\} and Bruno Delille and Frey, \{Markus M.\} and Dwayne Heard and Alexis Lamothe and Law, \{Kathy S.\} and Jingqiu Mao and S{\"o}nke Maus and Murphy, \{Jennifer G.\} and Peterson, \{Peter K.\} and Christian Pfrang and Francesca Salteri and Joel Savarino and Jochen Stutz and C{\'e}line Toubin and Xin Yang and Paul Zieger", year = "2025", month = jun, day = "1", doi = "10.1039/d5fd90015h", language = "English", volume = "258", pages = "568--596", journal = "Faraday Discussions", issn = "1359-6640", publisher = "Royal Society of Chemistry", } . Faraday Discussions.

General discussion @article{83112acd1d8b436eb7b8a2a52f5b0ae4, title = "General discussion: Aerosol formation and growth; VOC sources and secondary organic aerosols", author = "Alam, \{Mohammed Salim\} and William Bloss and James Brean and Peter Brimblecombe and Chak Chan and Ying Chen and Hugh Coe and Pingqing Fu and Shahzad Gani and Jacqueline Hamilton and Roy Harrison and Jingkun Jiang and Markku Kulmala and Lya Lugon and Gordon McFiggans and Archit Mehra and Adam Milsom and Beth Nelson and Christian Pfrang and Karine Sartelet and Zongbo Shi and Deepchandra Srivastava and Gareth Stewart and Peter Styring and Hang Su and \{Van Pinxteren\}, Dominik and Erik Velasco and Yu, \{Jian Zhen\}", year = "2021", month = mar, day = "9", doi = "10.1039/D1FD90011K", language = "English", volume = "226", pages = "479--501", journal = "Faraday Discussions", issn = "1359-6640", publisher = "Royal Society of Chemistry", } . Faraday Discussions.