Abstract. The photochemistry of carbonyl compounds significantly influences tropospheric chemical composition by altering the local oxidative capacity; free radical abundance in the upper troposphere; and formation of ozone, peroxycarboxylic nitric anhydride (PAN), and secondary organic aerosol particles. Carbonyl compounds can be emitted directly from the biosphere into the atmosphere and are formed through photochemical degradation of various precursor compounds. Aldehydes have atmospheric lifetimes of hours to days, whereas ketones persist for up to several weeks. While standard operating conditions for a proton-transfer-reaction time-of-flight mass spectrometer (PTR-ToF-MS) using H3O+ ions are unable to separate aldehydes and ketones, the use of NO+ reagent ions allows for the differential detection of isomeric carbonyl compounds with a high temporal resolution. Here we study the temporal (24 h) and vertical (80–325 m) variability of individual carbonyl compounds in the Amazon rainforest atmosphere with respect to their rainforest-specific sources and sinks. We found strong sources of ketones within or just above the canopy (acetone, methyl ethyl ketone (MEK), and C5 ketones). A common feature of the carbonyls was nocturnal deposition observed by loss rates, most likely since oxidized volatile organic compounds are rapidly metabolized and utilized by the biosphere. With NO+ chemical ionization, we show that the dominant carbonyl species include acetone and propanal, which are present at a ratio of 1 : 10 in the wet-to-dry transition season and 1 : 20 in the dry season.

Akima Ringsdorf

Achim Edtbauer

Bruna Holanda

Christopher Poehlker

Marta O. Sá

Alessandro Araújo

Jürgen Kesselmeier

Jos Lelieveld

Jonathan Williams

Atmospheric chemistry and physics

Investigating carbonyl compounds above the Amazon rainforest using a proton-transfer-reaction time-of-flight mass spectrometer (PTR-ToF-MS) with NO+ chemical ionization

利用NO+化学电离的质子转移反应飞行时间质谱仪（PTR-ToF-MS）研究亚马逊雨林上空的羰基化合物

Abstract. Accurate estimates of greenhouse gas emissions and sinks are critical for understanding the carbon cycle and identifying key drivers of anthropogenic climate change. In this study, we investigate the variability in CO and CO2 concentrations and their ratio over the Mexico City metropolitan area (MCMA) using long-term, time-resolved columnar measurements at three stations, employing solar-absorption Fourier transform infrared spectroscopy (FTIR). Using a simple model and the mixed-layer height derived from a ceilometer, we determined the CO and CO2 concentrations in the mixed layer from the total column measurements and found good agreement with surface cavity ring-down spectroscopy measurements. In addition, we used the diurnal pattern of CO columnar measurements at specific time intervals to estimate an average growth rate that, when combined with the space-based Tropospheric Monitoring Instrument (TROPOMI) CO measurements, allowed for the derivation of annual CO and CO2 MCMA emissions from 2016 to 2021. A CO emission decrease of more than 50 % was found during the COVID-19 lockdown period with respect to the year 2018. These results demonstrate the feasibility of using long-term EM27/SUN column measurements to monitor the annual variability in the anthropogenic CO2 and CO emissions in Mexico City without recourse to complex transport models. This simple methodology could be adapted to other urban areas if the orography of the regions favours low ventilation for several hours per day and the column growth rate is dominated by the emission flux.

Noémie Taquet

Wolfgang Stremme

María Eugenia González del Castillo

Victor Almanza

Alejandro Bezanilla

Olivier Laurent

Carlos Alberti

Frank Hase

Michel Ramonet

Thomas Lauvaux

Ke Che

Michel Grutter

CO2 and CO temporal variability over Mexico City from ground-based total column and surface measurements

墨西哥城基于地基总柱和地表测量所得的CO2和CO时间变异性研究

Abstract. Atmospheric aerosols strongly influence the global climate through their light absorption properties (e.g., black carbon (BC) and brown carbon (BrC)) and scattering properties (e.g., sulfate). This study presents simultaneous measurements of ambient-aerosol light absorption properties and chemical composition obtained at three large-footprint southern Asian receptor sites during the South Asian Pollution Experiment (SAPOEX) from December 2017 to March 2018. The BC mass absorption cross section (BC-MAC678) values increased from 3.5 ± 1.3 at the Bangladesh Climate Observatory at Bhola (BCOB), located at the exit outflow of the Indo-Gangetic Plain, to 6.4 ± 1.3 at two regional receptor observatories, the Maldives Climate Observatory at Hanimaadhoo (MCOH) and the Maldives Climate Observatory at Gan (MCOG), representing an increase of 80 %. This likely reflects a scavenging fractionation, resulting in a population of finer BC with higher MAC678 that has greater longevity. At the same time, BrC-MAC365 decreased by a factor of 3 from the Indo-Gangetic Plain (IGP) exit to the equatorial Indian Ocean, likely due to photochemical bleaching of organic chromophores. The high chlorine-to-sodium ratio at the BCOB, located near the source region, suggests a significant contribution of chorine from anthropogenic activities. Particulate Cl− has the potential to be converted into Cl radicals, which can affect the oxidation capacity of polluted air. Moreover, Cl− is shown to be nearly fully consumed during long-range transport. The results of this synoptic study, conducted on a large southern Asian scale, provide rare observational constraints on the optical properties of ambient BC (and BrC) aerosols over regional scales, away from emission sources. They also contribute significantly to understanding the aging effect of the optical and chemical properties of aerosols as pollution from the Indo-Gangetic Plain disperses over the tropical ocean.

Krishnakant Budhavant

Mohanan Remani Manoj

Hari Ram Chandrika Rajendran Nair

Samuel Mwaniki Gaita

Henry Holmstrand

Abdus Salam

Ahmed Muslim

Sreedharan Krishnakumari Satheesh

Örjan Gustafsson

Changing optical properties of black carbon and brown carbon aerosols during long-range transport from the Indo-Gangetic Plain to the equatorial Indian Ocean

印度-恒河平原至赤道印度洋长距离传输过程中黑碳和棕碳气溶胶光学性质的变化

Abstract. The phenomenon of high ice water content (HIWC) occurs in mesoscale convective systems (MCSs) when a large number of small ice particles with typical sizes of a few hundred micrometers, concentrations of the order of 102–103 L−1, and IWC exceeding 1 g m−3 are present at high altitudes. HIWC regions in MCSs may extend vertically up to 10 km above the melting layer and horizontally up to hundreds of kilometers, filling large volumes of the convective systems. HIWC has great geophysical significance due to its effect on precipitation formation, the hydrological cycle, and the radiative properties of MCSs. It is also recognized as a hazard for commercial aviation operations since it can result in engine power loss and in the malfunctioning of aircraft data probes. This study summarizes observational and numerical simulation efforts leading to the development of a conceptual model for the production of HIWC in tropical MCSs based on the data collected during the HAIC–HIWC campaign. It is hypothesized that secondary ice production (SIP) in the vicinity of the melting layer plays a key role in the formation and sustainability of HIWC. In situ observations suggest that the major SIP mechanism in the vicinity of the melting layer is related to the fragmentation of freezing drops (FFDs). Both in situ data and numerical simulations suggest that the recirculation of drops through the melting layer led to the amplification of SIP. The proposed conceptual model and simulation results motivate further efforts to extend reproducible laboratory measurements.

Alexei Korolev

Zhipeng Qu

Jason Milbrandt

Ivan Heckman

Mélissa Cholette

Mengistu Wolde

Cuong Nguyen

Greg M. McFarquhar

Paul Lawson

Ann M. Fridlind

High ice water content in tropical mesoscale convective systems (a conceptual model)

热带中尺度对流系统中的高冰水含量（概念模型）

Abstract. Temperature fluctuations induced by mountain waves can play a crucial role in the formation of polar stratospheric clouds (PSCs). In particular, the cold phase of the waves can lower local temperatures sufficiently to trigger PSC formation, even when large-scale background temperatures are too high. To provide new quantitative constraints on the relevance of this effect, this study analyzes a decade (2002–2012) of ice PSC detections obtained from Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) measurements and ERA5 data in the polar winter lower stratosphere. In the MIPAS observations, we find that approximately 52 % of the Arctic ice PSCs and 26 % of the Antarctic ice PSCs are detected at temperatures above the local Tice. Ice PSCs above Tice are concentrated around mountainous regions and their downwind directions. A backward-trajectory analysis is performed to investigate the temperature history of each ice PSC observation. The cumulative fraction of ice PSCs above Tice increases as the trajectory gets closer to the observation point. The most significant change in the fraction of ice PSCs above Tice occurs within the 6 h preceding the observations. At the observation point, the mean fractions of ice PSCs above Tice, taking into account temperature fluctuations along the backward trajectory, are 33 % in the Arctic and 9 % in the Antarctic. The results provide a quantitative assessment of the occurrence of ice PSCs above Tice in connection with orographic waves. Additionally, the observational statistics presented can be utilized for comparison with chemistry climate simulations.

Ling Zou

Reinhold Spang

Sabine Griessbach

Lars Hoffmann

Farahnaz Khosrawi

Rolf Müller

Ines Tritscher

Impact of mountain-wave-induced temperature fluctuations on the occurrence of polar stratospheric ice clouds: a statistical analysis based on MIPAS observations and ERA5 data

山波诱导温度波动对极地平流层冰云出现的影响：基于MIPAS观测和ERA5数据的统计分析

Abstract. China has implemented some air pollution management measures in recent years, yet severe ozone pollution remains a significant issue. The southeastern coast of China (SECC) is often influenced by hot extremes and tropical cyclones (TCs), and the two can occur simultaneously (TC–HDs). The compound TC–HDs show a rising trend in the summers of 2014–2019, potentially affecting ozone pollution. Here, we found that surface ozone concentrations over the SECC are more elevated during extremely hot days than the summer climatology. However, compared to extremely hot days alone (AHDs), the maximum 8 h average ozone (MDA8 O3) concentration increases by an average of 6.8 µg m−3 in the Pearl River Delta (PRD) and decreases by 13.2 µg m−3 in the Yangtze River Delta (YRD) during the compound TC–HDs. The meteorological conditions during AHDs favor the chemical production of ozone over the SECC, exhibiting increased temperature and solar radiation and decreased relative humidity. Relative to AHDs, strong northeasterly winds prevail in the SECC during TC–HDs, suggesting the potential of ozone cross-regional transport between YRD and PRD. The process analysis in the chemical transport model (GEOS-Chem) suggests that relative to AHDs, the chemical production of ozone is enhanced in YRD during TC–HDs, while horizontal transport alleviates ozone pollution in YRD but worsens it in PRD through cross-regional transport. The results highlight the significant effects of cross-regional transport in modulating ozone pollution in the two megacity clusters during hot extremes accompanied by TC activities, giving insight into future ozone control measures over the SECC under global warming.

Cuini Qi

Pinya Wang

Yang Yang

Huimin Li

Hui Zhang

Lili Ren

Xipeng Jin

Chenchao Zhan

Jianping Tang

Hong Liao

Impacts of tropical cyclone–heat wave compound events on surface ozone in eastern China: comparison between the Yangtze River and Pearl River deltas

热带气旋-热浪复合事件对中国东部地面臭氧的影响：长江三角洲与珠江三角洲的比较

Abstract. Nitrogen oxides, emitted from air traffic, are of concern due to their impact on climate by changing atmospheric ozone and methane levels. Using the DLR research aircraft Falcon, total reactive nitrogen (NOy) in-flight measurements were carried out at high altitudes to characterize emissions in the fresh aircraft exhaust from the latest-generation Rolls-Royce Trent XWB-84 engine aboard the long-range Airbus A350-941 aircraft during the ECLIF3 (Emission and CLimate Impact of alternative Fuels 3) experiment. The impact of different engine thrust settings, monitored in terms of combustor inlet temperature, pressure and engine fuel flow, was tested for two different fuel types: Jet A-1 and, for the first time, a 100 % sustainable aviation fuel (SAF) under similar atmospheric conditions. In addition, a range of combustor temperatures and an additional blended SAF were tested during ground-based emission measurements. For the data measured during ECLIF3, we confirm that the NOx emission index increases with increasing combustion temperature, pressure and fuel flow. We find that as expected, the fuel type has no measurable effect on the NOx emission index. These measurements are used to compare to cruise NOx emission index estimates from three engine emission prediction methods. Our measurements thus help to understand the ground to cruise correlation of current engine emission prediction methods while serving as input for climate modelling and extending the extremely sparse data set on in-flight aircraft nitrogen oxide emissions to newer engine generations.

Theresa Harlass

Rebecca Dischl

Stefan Kaufmann

Raphael Märkl

Daniel Sauer

Monika Scheibe

Paul Stock

Tiziana Bräuer

Andreas Dörnbrack

Anke Roiger

Hans Schlager

Ulrich Schumann

Magdalena Pühl

Tobias Schripp

Tobias Grein

Linda Bondorf

Charles Renard

Maxime Gauthier

Mark Johnson

Darren Luff

Paul Madden

Peter Swann

Denise Ahrens

Reetu Sallinen

Christiane Voigt

Measurement report: In-flight and ground-based measurements of nitrogen oxide emissions from latest-generation jet engines and 100 % sustainable aviation fuel

测量报告：最新一代喷气发动机和100%可持续航空燃料的氮氧化物排放的机载和地面测量

Abstract. The aerosol particles serving as cloud condensation and ice nuclei contribute to key cloud processes associated with cold-air outbreak (CAO) events but are poorly constrained in climate models due to sparse observations. Here we retrieve aerosol number size distribution modes from measurements at Andenes, Norway, during the Cold-Air Outbreaks in the Marine Boundary Layer Experiment (COMBLE) and at Zeppelin Observatory, approximately 1000 km upwind from Andenes at Svalbard. During CAO events at Andenes, the sea-spray-mode number concentration is correlated with strong over-ocean winds with a mean of 8±4 cm−3 that is 71 % higher than during non-CAO conditions. Additionally, during CAO events at Andenes, the mean Hoppel minimum diameter is 6 nm smaller than during non-CAO conditions, though the estimated supersaturation is lower, and the mean number concentration of particles that likely activated in-cloud is 109±61 cm−3 with no statistically significant difference from the non-CAO mean of 99±66 cm−3. For CAO trajectories between Zeppelin Observatory and Andenes, the upwind-to-downwind change in number concentration is the largest for the accumulation mode with a mean decrease of 93±95 cm−3, likely attributable primarily to precipitation scavenging. These characteristic properties of aerosol number size distributions during CAO events provide guidance for evaluating CAO aerosol–cloud interaction processes in models.

Abigail S. Williams

Jeramy L. Dedrick

Lynn M. Russell

Florian Tornow

Israel Silber

Benjamin Swanson

Paul J. DeMott

Paul Zieger

Radovan Krejci

Aerosol size distribution properties associated with cold-air outbreaks in the Norwegian Arctic

挪威北极地区冷空气爆发相关的气溶胶粒径分布特性

Abstract. Cloud properties are strongly influenced by ice formation; hence, we need to understand the sources of ice-nucleating particles (INPs) around the globe. Boreal forests are known as sources of bioaerosol, and recent work indicates that these dominate the INP spectra above −24 °C. To quantify the INP population at temperatures below −24 °C, we deployed a portable cloud expansion chamber (PINE) in a Finnish boreal forest from 13 March 2018 to 11 May 2018. Using the 6 min time resolution PINE data, we present several lines of evidence that INPs below −24 °C in this location are also from biological sources: (i) an INP parameterization developed for a pine forest site in Colorado, where many INPs were shown to be biological, produced a good fit to our measurements; a moderate correlation of INPs with aerosol concentration larger than 0.5 µm and the fluorescent bioaerosol concentration; (ii) a negative correlation with relative humidity that may relate to enhanced release of bioaerosol at low humidity from local sources such as the prolific lichen population in boreal forests; and (iii) the absence of correlation with ultra-fine particles (3.5 to 50 nm), indicating that new particle formation events are not sources of INPs. This study should motivate further work to establish whether the commonality in bioaerosol ice-nucleating properties between spring in Finland and summer in Colorado is more generally applicable to different coniferous forest locations and times and also to determine to what extent these bioaerosols are transported to locations where they may affect clouds.

Franziska Vogel

Michael P. Adams

Larissa Lacher

Polly B. Foster

Grace C. E. Porter

Barbara Bertozzi

Kristina Höhler

Julia Schneider

Tobias Schorr

Nsikanabasi S. Umo

Jens Nadolny

Zoé Brasseur

Paavo Heikkilä

Erik S. Thomson

Nicole Büttner

Martin I. Daily

Romy Fösig

Alexander D. Harrison

Jorma Keskinen

Ulrike Proske

Jonathan Duplissy

Markku Kulmala

Tuukka Petäjä

Ottmar Möhler

Benjamin J. Murray

Ice-nucleating particles active below −24 °C in a Finnish boreal forest and their relationship to bioaerosols

芬兰北方森林中在低于−24°C条件下活跃的冰核颗粒及其与生物气溶胶的关系

Abstract. Volatile organic compounds (VOCs) are often subject to synergistic oxidation by different oxidants in the atmosphere. However, the exact synergistic-oxidation mechanism of atmospheric VOCs and its role in particle formation remain poorly understood. In particular, the reaction kinetics of the key reactive intermediates, organic peroxy radicals (RO2), during synergistic oxidation is rarely studied. Here, we conducted a combined experimental and kinetic modeling study of the nocturnal synergistic oxidation of α-pinene (the most abundant monoterpene) by O3 and NO3 radicals as well as its influences on the formation of highly oxygenated organic molecules (HOMs) and particles. We find that in the synergistic O3 + NO3 regime, where OH radicals are abundantly formed via decomposition of ozonolysis-derived Criegee intermediates, the production of CxHyOz HOMs is substantially suppressed compared to that in the O3-only regime, mainly because of the depletion of α-pinene RO2 derived from ozonolysis and OH oxidation by those arising from NO3 oxidation via cross reactions. Measurement–model comparisons further reveal that the cross-reaction rate constants of NO3-derived RO2 with O3-derived RO2 are on average 10–100 times larger than those of NO3-derived RO2 with OH-derived RO2. Despite a strong production of organic nitrates in the synergistic-oxidation regime, the substantial decrease in CxHyOz HOM formation leads to a significant reduction in ultralow- and extremely low-volatility organic compounds, which significantly inhibits the formation of new particles. This work provides valuable mechanistic and quantitative insights into the nocturnal synergistic-oxidation chemistry of biogenic emissions and will help to better understand the formation of low-volatility organic compounds and particles in the atmosphere.

Han Zang

Zekun Luo

Chenxi Li

Ziyue Li

Dandan Huang

Yue Zhao

Nocturnal atmospheric synergistic oxidation reduces the formation of low-volatility organic compounds from biogenic emissions

夜间大气协同氧化作用减少生物源排放的低挥发性有机化合物形成

ATMOSPHERIC CHEMISTRY AND PHYSICS (ACP) 是一本非营利性国际科学期刊，致力于出版和公开讨论调查地球大气及其潜在化学和物理过程的高质量研究。它涵盖的海拔范围从陆地和海洋表面直至涡轮顶，包括对流层、平流层和中间层。主要学科领域包括大气建模、实地测量、遥感以及气体、气溶胶、云和降水、同位素、辐射、动力学的实验室研究，生物圈相互作用和水圈相互作用期刊范围侧重于对大气科学具有一般意义的研究，而不是主要具有当地或技术兴趣的调查。

Atmospheric Chemistry and Physics (ACP) is a non-profit international scientific journal dedicated to publishing and discussing high-quality research on the Earth's atmosphere and its potential chemical and physical processes. The scope of the journal ranges from the land and ocean surfaces to the tropopause, covering the troposphere, stratosphere, and mesosphere. Major subject areas include atmospheric modeling, field measurements, remote sensing, as well as laboratory studies on gases, aerosols, clouds and precipitation, isotopes, radiation, and dynamics, along with interactions in the biosphere and hydrosphere. The journal focuses on research that has general significance for atmospheric science rather than investigations primarily of local or technical interest.

《Atmospheric Chemistry and Physics》（ACP）是一本非营利性国际科学期刊，专注于发布和讨论关于地球大气及其潜在化学和物理过程的高质量研究。期刊涵盖的研究范围从陆地和海洋表面到涡轮顶，包括对流层、平流层和中间层。主要学科领域包括大气建模、实地测量、遥感技术，以及气体、气溶胶、云和降水、同位素、辐射、动力学的实验室研究，生物圈和水圈的相互作用。该期刊的重点是对大气科学具有普遍意义的研究，而非仅限于地方性或技术性兴趣的调查。

Atmospheric Chemistry and Physics

期刊	Atmospheric Chemistry and Physics
ISSN	1680-7316, 1680-7324
h-index	253
Journal Impact	5.30
国际分区	METEOROLOGY & ATMOSPHERIC SCIENCES(Q1)
国内分区	地球科学(1区)地球科学气象与大气科学(1区)地球科学环境科学(2区)