Articles | Volume 18, issue 2
Atmos. Chem. Phys., 18, 1203–1216, 2018
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 3.0 License.
the Creative Commons Attribution 3.0 License.
Research article 30 Jan 2018
Research article | 30 Jan 2018
Transport of regional pollutants through a remote trans-Himalayan valley in Nepal
Shradda Dhungel et al.
No articles found.
Md. Robiul Islam, Thilina Jayarathne, Isobel J. Simpson, Benjamin Werden, John Maben, Ashley Gilbert, Puppala S. Praveen, Sagar Adhikari, Arnico K. Panday, Maheswar Rupakheti, Donald R. Blake, Robert J. Yokelson, Peter F. DeCarlo, William C. Keene, and Elizabeth A. Stone
Atmos. Chem. Phys., 20, 2927–2951,Short summary
The Kathmandu Valley experiences high levels of air pollution. In this study, atmospheric gases and particulate matter were characterized by online and off-line measurements, with an emphasis on understanding their sources. The major sources of particulate matter and trace gases were identified as garbage burning, biomass burning, and vehicles. The majority of secondary organic aerosol was attributed to anthropogenic precursors, while a minority was attributed to biogenic gases.
Min Zhong, Eri Saikawa, Alexander Avramov, Chen Chen, Boya Sun, Wenlu Ye, William C. Keene, Robert J. Yokelson, Thilina Jayarathne, Elizabeth A. Stone, Maheswar Rupakheti, and Arnico K. Panday
Atmos. Chem. Phys., 19, 8209–8228,Short summary
Air pollution is one of the most pressing environmental issues in the Kathmandu Valley, the capital city of Nepal. We estimated emissions from two of the major source types in the valley (vehicles and brick kilns) and found that they have significant impacts on air quality surrounding the valley. Our results highlight the importance of improving local emissions estimates for air quality modeling.
Xin Wan, Shichang Kang, Maheswar Rupakheti, Qianggong Zhang, Lekhendra Tripathee, Junming Guo, Pengfei Chen, Dipesh Rupakheti, Arnico K. Panday, Mark G. Lawrence, Kimitaka Kawamura, and Zhiyuan Cong
Atmos. Chem. Phys., 19, 2725–2747,Short summary
The sources of primary and secondary aerosols in the Hindu Kush–Himalayan–Tibetan Plateau region are not well known. Organic molecular tracers are useful for aerosol source apportionment. The characterization of molecular tracers were first systemically investigated and the contribution from primary and secondary sources to carbonaceous aerosols was estimated in the Kathmandu Valley. Our results demonstrate that biomass burning contributed a significant fraction to OC in the Kathmandu Valley.
Ashish Singh, Khadak S. Mahata, Maheswar Rupakheti, Wolfgang Junkermann, Arnico K. Panday, and Mark G. Lawrence
Atmos. Chem. Phys., 19, 245–258,Short summary
This paper reports the first airborne measurement campaign in the central Himalayan foothill region, one of the polluted but relatively poorly sampled regions of the world. The measurement campaign quantifies the vertical distribution of aerosols over a polluted mountain valley in the Himalayan foothills and investigates the extent of regional emission transport.
J. Douglas Goetz, Michael R. Giordano, Chelsea E. Stockwell, Ted J. Christian, Rashmi Maharjan, Sagar Adhikari, Prakash V. Bhave, Puppala S. Praveen, Arnico K. Panday, Thilina Jayarathne, Elizabeth A. Stone, Robert J. Yokelson, and Peter F. DeCarlo
Atmos. Chem. Phys., 18, 14653–14679,Short summary
Size distributions and emission factors of submicron aerosol were quantified using online techniques for a variety of common but under-sampled combustion sources in South Asia: wood and dung cooking fires, groundwater pumps, brick kilns, trash burning, and open burning of crop residues. Optical properties (brown carbon light absorption and the absorption Ångström exponent, AAE) of the emissions were also investigated. Contextual comparisons to the literature and other NAMaSTE results were made.
Khadak Singh Mahata, Maheswar Rupakheti, Arnico Kumar Panday, Piyush Bhardwaj, Manish Naja, Ashish Singh, Andrea Mues, Paolo Cristofanelli, Deepak Pudasainee, Paolo Bonasoni, and Mark G. Lawrence
Atmos. Chem. Phys., 18, 14113–14132,Short summary
This paper presents the first-time simultaneous measurement of CO and O3 at multiple sites in the Kathmandu Valley bottom, its mountain rim and a river outlet, providing their spatial, temporal and seasonal–diurnal variations. Our study reveals that high O3, especially during premonsoon, in observed sites is of high concern for human health and ecosystems in the region. We also estimated CO emission flux to be 2–14 times higher than widely used emission databases (EDGAR HTAP, REAS and INTEX-B).
Piyush Bhardwaj, Manish Naja, Maheswar Rupakheti, Aurelia Lupascu, Andrea Mues, Arnico Kumar Panday, Rajesh Kumar, Khadak Singh Mahata, Shyam Lal, Harish C. Chandola, and Mark G. Lawrence
Atmos. Chem. Phys., 18, 11949–11971,Short summary
This study provides information about the regional variabilities in some of the pollutants using observations in Nepal and India. It is shown that agricultural crop residue burning leads to a significant enhancement in ozone and CO over a wider region. Further, the wintertime higher ozone levels are shown to be largely due to local emissions, while regional transport could be important in spring and hence shows the role of regional sources versus local sources in the Kathmandu Valley.
Thilina Jayarathne, Chelsea E. Stockwell, Prakash V. Bhave, Puppala S. Praveen, Chathurika M. Rathnayake, Md. Robiul Islam, Arnico K. Panday, Sagar Adhikari, Rashmi Maharjan, J. Douglas Goetz, Peter F. DeCarlo, Eri Saikawa, Robert J. Yokelson, and Elizabeth A. Stone
Atmos. Chem. Phys., 18, 2259–2286,Short summary
Emissions of fine particulate matter and its constituents were quantified for a variety of under-sampled combustion sources in South Asia: wood and dung cooking fires, generators, groundwater pumps, brick kilns, trash burning, and open burning of biomasses. Garbage burning and three-stone cooking fires were among the highest emitters, while servicing of motor vehicles significantly reduced PM. These data may be used in source apportionment and to update regional and global emission inventories.
Khadak Singh Mahata, Arnico Kumar Panday, Maheswar Rupakheti, Ashish Singh, Manish Naja, and Mark G. Lawrence
Atmos. Chem. Phys., 17, 12573–12596,Short summary
The paper provides an overview of CH4, CO2, and CO mixing ratios, including diurnal and seasonal variation, and discusses the association of potential sources and meteorology with the observed temporal variation in the Kathmandu Valley. The study will provide an important dataset for a poorly studied region and will be useful for validating estimates from emission inventories, regional models, and satellite observations and assisting in the design of mitigation measures in the region.
Chaeyoon Cho, Sang-Woo Kim, Maheswar Rupakheti, Jin-Soo Park, Arnico Panday, Soon-Chang Yoon, Ji-Hyoung Kim, Hyunjae Kim, Haeun Jeon, Minyoung Sung, Bong Mann Kim, Seungkyu K. Hong, Rokjin J. Park, Dipesh Rupakheti, Khadak Singh Mahata, Puppala Siva Praveen, Mark G. Lawrence, and Brent Holben
Atmos. Chem. Phys., 17, 12617–12632,Short summary
We investigated the optical and chemical properties and direct radiative effects of aerosols in the Kathmandu Valley. We concluded that the ratio of light-absorbing to scattering aerosols as well as the concentration of light-absorbing aerosols is much higher at Kathmandu than other comparable regions, and it contributes to a great atmospheric absorption efficiency. This study provides unprecedented insights into aerosol optical properties and their radiative forcings in the Kathmandu Valley.
Dipesh Rupakheti, Bhupesh Adhikary, Puppala Siva Praveen, Maheswar Rupakheti, Shichang Kang, Khadak Singh Mahata, Manish Naja, Qianggong Zhang, Arnico Kumar Panday, and Mark G. Lawrence
Atmos. Chem. Phys., 17, 11041–11063,Short summary
For the first time, atmospheric composition was monitored during pre-monsoon season of 2013 at Lumbini (UNESCO world heritage site as birthplace of the Buddha). PM and O3 frequently exceeded WHO guidelines. Pollution concentration, diurnal characteristics and influence of open burning on air quality in Lumbini were investigated. Potential source regions were also identified. Results show that air pollution at this site is of a great concern, requiring prompt attention for mitigation.
Xin Wan, Shichang Kang, Quanlian Li, Dipesh Rupakheti, Qianggong Zhang, Junming Guo, Pengfei Chen, Lekhendra Tripathee, Maheswar Rupakheti, Arnico K. Panday, Wu Wang, Kimitaka Kawamura, Shaopeng Gao, Guangming Wu, and Zhiyuan Cong
Atmos. Chem. Phys., 17, 8867–8885,Short summary
Biomass burning (BB) tracers in the aerosols in Lumbini, northern IGP, were studied for the first time. The levoglucosan was the predominant tracer and BB significantly contributed to the air quality in Lumbini. Mixed crop residues and hardwood were main burning materials. BB emissions constituted large fraction of OC, especially during the post-monsoon season. The sources of BB aerosols in Lumbini varies seasonally due to the influence of local emissions and long-range transport.
Chinmoy Sarkar, Vinayak Sinha, Baerbel Sinha, Arnico K. Panday, Maheswar Rupakheti, and Mark G. Lawrence
Atmos. Chem. Phys., 17, 8129–8156,Short summary
This study provides quantitative information regarding the source contributions of the major non-methane volatile organic compound sources in the Kathmandu Valley. Combining high-resolution in situ NMVOC data and model analyses, we show that REAS v2.1 and EDGAR v4.2 emission inventories underestimate the contribution of traffic and do not take the contribution of brick kilns into account. Furthermore, REAS v2.1 overestimates the contribution of residential biofuel use and industries.
Kabindra M. Shakya, Maheswar Rupakheti, Anima Shahi, Rejina Maskey, Bidya Pradhan, Arnico Panday, Siva P. Puppala, Mark Lawrence, and Richard E. Peltier
Atmos. Chem. Phys., 17, 6503–6516,Short summary
Particulate matter levels were monitored at six major roadway intersections in the Kathmandu Valley during two seasons in 2014. The study documented distinct seasonal (dry season versus wet season) and diel variations in particulate matter levels. This study suggests traffic-related emissions, and soil–dust–construction materials were found to be a major source of particulate matter at these locations.
Sujan Shrestha, Siva Praveen Puppala, Bhupesh Adhikary, Kundan Lal Shrestha, and Arnico K. Panday
Atmos. Chem. Phys. Discuss.,
Revised manuscript not accepted
Chelsea E. Stockwell, Ted J. Christian, J. Douglas Goetz, Thilina Jayarathne, Prakash V. Bhave, Puppala S. Praveen, Sagar Adhikari, Rashmi Maharjan, Peter F. DeCarlo, Elizabeth A. Stone, Eri Saikawa, Donald R. Blake, Isobel J. Simpson, Robert J. Yokelson, and Arnico K. Panday
Atmos. Chem. Phys., 16, 11043–11081,Short summary
We present the first, or rare, field measurements in South Asia of emission factors for up to 80 gases (pollutants, greenhouse gases, and precursors) and black carbon and aerosol optical properties at 405 and 870 nm for many previously under-sampled sources that are important in developing countries such as cooking with dung and wood, garbage and crop residue burning, brick kilns, motorcycles, generators and pumps, etc. Brown carbon contributes significantly to total aerosol absorption.
Chinmoy Sarkar, Vinayak Sinha, Vinod Kumar, Maheswar Rupakheti, Arnico Panday, Khadak S. Mahata, Dipesh Rupakheti, Bhogendra Kathayat, and Mark G. Lawrence
Atmos. Chem. Phys., 16, 3979–4003,Short summary
First deployment of PTR-TOF-MS in South Asia. High acetaldehyde and biogenic isoprene concentrations detected even in winter in the Kathmandu Valley. Isocyanic acid, formamide, acetamide, naphthalene and nitromethane were detected for the first time in South Asian air. Oxygenated VOCs and isoprene-dominated OH reactivity and ozone production potentials (> 68 % OPP). Regulation of emissions from biomass co-fired brick kilns' by cleaner technology would improve air quality of the valley.
Peng Fei Chen, Chao Liu Li, Shi Chang Kang, Maheswar Rupakheti, Arnico K. Panday, Fang Ping Yan, Quan Lian Li, Qiang Gong Zhang, Jun Ming Guo, Dipesh Rupakheti, and Wei Luo
Atmos. Chem. Phys. Discuss.,
Revised manuscript not acceptedShort summary
PAHs were measured at six sites along two south-north transects across the central Himalayas. The annual average PAHs and their dry deposition fluxes decreased noticeably from the south to north sides, however, a similar compostion pattern was found at three remote sites, suggesting the northern slope of the Himalayas may be affected by anthropogenic emissions form Indo-Gangetic Plain. PAHs showed a clear seasonal variation at Nepal and they were mainly form biomass and fossil combustion .
D. Putero, P. Cristofanelli, A. Marinoni, B. Adhikary, R. Duchi, S. D. Shrestha, G. P. Verza, T. C. Landi, F. Calzolari, M. Busetto, G. Agrillo, F. Biancofiore, P. Di Carlo, A. K. Panday, M. Rupakheti, and P. Bonasoni
Atmos. Chem. Phys., 15, 13957–13971,Short summary
The aim of this paper is to present a full-year analysis of simultaneous measurements of ozone, black carbon, and aerosol number concentration at Paknajol, in the Kathmandu Valley, one of the global “hot spots” in terms of air pollution. Results indicate persisting poor air quality conditions throughout the measurement period, and suggest that the pollutants' variability is mainly driven by local pollution source activity, local- and large-scale dynamics, photochemistry, and vegetation fires.
Related subject area
Subject: Aerosols | Research Activity: Field Measurements | Altitude Range: Troposphere | Science Focus: Physics (physical properties and processes)PM2.5 surface concentrations in southern West African urban areas based on sun photometer and satellite observationsObservations on aerosol optical properties and scavenging during cloud eventsAssessing the vertical structure of Arctic aerosols using balloon-borne measurementsAn overview of the ORACLES (ObseRvations of Aerosols above CLouds and their intEractionS) project: aerosol–cloud–radiation interactions in the southeast Atlantic basinMeasurement report: aerosol hygroscopic properties extended to 600 nm in the urban environmentSpatiotemporal variation and trends in equivalent black carbon in the Helsinki metropolitan area in FinlandCharacteristics of sub-10 nm particle emissions from in-use commercial aircraft observed at Narita International AirportThe CLoud–Aerosol–Radiation Interaction and Forcing: Year 2017 (CLARIFY-2017) measurement campaignMeasurement report: quantifying source contribution of fossil fuels and biomass-burning black carbon aerosol in the southeastern margin of the Tibetan PlateauThe electrical activity of Saharan dust as perceived from surface electric field observationsLong-term measurement of sub-3 nm particles and their precursor gases in the boreal forestVariability in the mass absorption cross section of black carbon (BC) aerosols is driven by BC internal mixing state at a central European background site (Melpitz, Germany) in winterOptical and hygroscopic properties of black carbon influenced by particle microphysics at the top of the anthropogenically polluted boundary layerMeasurement report: Properties of aerosol and gases in the vertical profile during the LAPSE-RATE campaignAircraft vertical profiles during summertime regional and Saharan dust scenarios over the north-western Mediterranean basin: aerosol optical and physical propertiesAfrican dust particles over the western Caribbean – Part I: Impact on air quality over the Yucatán PeninsulaDirect measurements of black carbon fluxes in central Beijing using the eddy covariance methodMeasurements to determine the mixing state of black carbon emitted from the 2017–2018 California wildfires and urban Los AngelesWhat can we learn about urban air quality with regard to the first outbreak of the COVID-19 pandemic? A case study from central EuropeMeasurement report: Source and mixing state of black carbon aerosol in the North China Plain: implications for radiative effectThe potential role of organics in new particle formation and initial growth in the remote tropical upper troposphereImpacts of long-range transport of aerosols on marine-boundary-layer clouds in the eastern North AtlanticInfluence of vegetation on occurrence and time distributions of regional new aerosol particle formation and growthQuantifying bioaerosol concentrations in dust clouds through online UV-LIF and mass spectrometry measurements at the Cape Verde Atmospheric ObservatoryNew particle formation at urban and high-altitude remote sites in the south-eastern Iberian PeninsulaCharacterization of submicron organic particles in Beijing during summertime: comparison between SP-AMS and HR-AMSThe characterization of Taklamakan dust properties using a multiwavelength Raman polarization lidar in Kashi, ChinaFrom a polar to a marine environment: has the changing Arctic led to a shift in aerosol light scattering properties?Atmospheric new particle formation characteristics in the Arctic as measured at Mount Zeppelin, Svalbard, from 2016 to 2018Rapid evolution of aerosol particles and their optical properties downwind of wildfires in the western USDistinct aerosol effects on cloud-to-ground lightning in the plateau and basin regions of Sichuan, Southwest ChinaSpatial and temporal representativeness of point measurements for nitrogen dioxide pollution levels in citiesVertical variability of the properties of highly aged biomass burning aerosol transported over the southeast Atlantic during CLARIFY-2017Large contribution of organics to condensational growth and formation of cloud condensation nuclei (CCN) in the remote marine boundary layerDecennial time trends and diurnal patterns of particle number concentrations in a central European city between 2008 and 2018Roles of climate variability on the rapid increases of early winter haze pollution in North China after 2010Drivers of cloud droplet number variability in the summertime in the southeastern United StatesRoll vortices induce new particle formation bursts in the planetary boundary layerDeposition of light-absorbing particles in glacier snow of the Sunderdhunga Valley, the southern forefront of Central HimalayaLarge-scale ion generation for precipitation of atmospheric aerosolsAerosol light absorption and the role of extremely low volatility organic compoundsSize-resolved particle number emissions in Beijing determined from measured particle size distributionsEffects of marine fuel sulfur restrictions on particle number concentrations and size distributions in ship plumes at the Baltic SeaDaytime aerosol optical depth above low-level clouds is similar to that in adjacent clear skies at the same heights: airborne observation above the southeast AtlanticAbsorption closure in highly aged biomass burning smokeAerosol pollution maps and trends over Germany with hourly data at four rural background stations from 2009 to 2018Measurement report: Cloud Processes and the Transport of Biological Emissions Regulate Southern Ocean Particle and Cloud Condensation Nuclei ConcentrationsDominant synoptic patterns associated with the decay process of PM2.5 pollution episodes around BeijingVertical profiles of light absorption and scattering associated with black carbon particle fractions in the springtime Arctic above 79° NContrasting impacts of two types of El Niño events on winter haze days in China's Jing-Jin-Ji region
Jean-François Léon, Aristide Barthélémy Akpo, Mouhamadou Bedou, Julien Djossou, Marleine Bodjrenou, Véronique Yoboué, and Cathy Liousse
Atmos. Chem. Phys., 21, 1815–1834,Short summary
We have investigated the aerosol optical depth (AOD) and its relation to PM2.5 surface concentrations in southern West Africa based on in situ observations (2015–2017 period) and MODIS satellite data (2003–2019). MODIS AODs are validated using a regional network of handheld and automatic sun photometers. Satellite-derived PM2.5 shows an increasing trend during the short dry period that is possibly linked to the increase in anthropogenic emission over this area.
Antti Ruuskanen, Sami Romakkaniemi, Harri Kokkola, Antti Arola, Santtu Mikkonen, Harri Portin, Annele Virtanen, Kari E. J. Lehtinen, Mika Komppula, and Ari Leskinen
Atmos. Chem. Phys., 21, 1683–1695,Short summary
The study focuses mainly on cloud-scavenging efficiency of absorbing particulate matter (mainly black carbon) but additionally covers cloud-scavenging efficiency of scattering particles and statistics of cloud condensation nuclei. The main findings give insight into how black carbon is distributed in different particle sizes and the sensitivity to cloud scavenged. The main findings are useful for large-scale modelling for evaluating cloud scavenging.
Jessie M. Creamean, Gijs de Boer, Hagen Telg, Fan Mei, Darielle Dexheimer, Matthew D. Shupe, Amy Solomon, and Allison McComiskey
Atmos. Chem. Phys., 21, 1737–1757,Short summary
Arctic clouds play a role in modulating sea ice extent. Importantly, aerosols facilitate cloud formation, and thus it is crucial to understand the interactions between aerosols and clouds. Vertical measurements of aerosols and clouds are needed to tackle this issue. We present results from balloon-borne measurements of aerosols and clouds over the course of 2 years in northern Alaska. These data shed light onto the vertical distributions of aerosols relative to clouds spanning multiple seasons.
Jens Redemann, Robert Wood, Paquita Zuidema, Sarah J. Doherty, Bernadette Luna, Samuel E. LeBlanc, Michael S. Diamond, Yohei Shinozuka, Ian Y. Chang, Rei Ueyama, Leonhard Pfister, Ju-Mee Ryoo, Amie N. Dobracki, Arlindo M. da Silva, Karla M. Longo, Meloë S. Kacenelenbogen, Connor J. Flynn, Kristina Pistone, Nichola M. Knox, Stuart J. Piketh, James M. Haywood, Paola Formenti, Marc Mallet, Philip Stier, Andrew S. Ackerman, Susanne E. Bauer, Ann M. Fridlind, Gregory R. Carmichael, Pablo E. Saide, Gonzalo A. Ferrada, Steven G. Howell, Steffen Freitag, Brian Cairns, Brent N. Holben, Kirk D. Knobelspiesse, Simone Tanelli, Tristan S. L'Ecuyer, Andrew M. Dzambo, Ousmane O. Sy, Greg M. McFarquhar, Michael R. Poellot, Siddhant Gupta, Joseph R. O'Brien, Athanasios Nenes, Mary Kacarab, Jenny P. S. Wong, Jennifer D. Small-Griswold, Kenneth L. Thornhill, David Noone, James R. Podolske, K. Sebastian Schmidt, Peter Pilewskie, Hong Chen, Sabrina P. Cochrane, Arthur J. Sedlacek, Timothy J. Lang, Eric Stith, Michal Segal-Rozenhaimer, Richard A. Ferrare, Sharon P. Burton, Chris A. Hostetler, David J. Diner, Felix C. Seidel, Steven E. Platnick, Jeffrey S. Myers, Kerry G. Meyer, Douglas A. Spangenberg, Hal Maring, and Lan Gao
Atmos. Chem. Phys., 21, 1507–1563,Short summary
Southern Africa produces significant biomass burning emissions whose impacts on regional and global climate are poorly understood. ORACLES (ObseRvations of Aerosols above CLouds and their intEractionS) is a 5-year NASA investigation designed to study the key processes that determine these climate impacts. The main purpose of this paper is to familiarize the broader scientific community with the ORACLES project, the dataset it produced, and the most important initial findings.
Chuanyang Shen, Gang Zhao, Weilun Zhao, Ping Tian, and Chunsheng Zhao
Atmos. Chem. Phys., 21, 1375–1388,Short summary
Submicron particles larger than 300 nm dominate the aerosol light extinction and mass concentration in the urban environment. Aerosol hygroscopic properties extended to 600 nm were investigated at an urban site. Our results find that there exists a large fraction of a less hygroscopic group above 300 nm, and the hygroscopicity in this size range is enhanced significantly with the development of pollution levels. The hygroscopicity variation contributes greatly to the low visibility.
Krista Luoma, Jarkko V. Niemi, Minna Aurela, Pak Lun Fung, Aku Helin, Tareq Hussein, Leena Kangas, Anu Kousa, Topi Rönkkö, Hilkka Timonen, Aki Virkkula, and Tuukka Petäjä
Atmos. Chem. Phys., 21, 1173–1189,Short summary
This study combined black carbon measurements from 15 Finnish sites that represented different environments (traffic, detached housing area, urban background, and regional background). The seasonal and diurnal variations in the black carbon concentration were associated with local emissions from traffic and residential wood burning. The study observed decreasing trends in the black carbon concentration and associated them with decreases in traffic emissions.
Nobuyuki Takegawa, Yoshiko Murashima, Akihiro Fushimi, Kentaro Misawa, Yuji Fujitani, Katsumi Saitoh, and Hiromu Sakurai
Atmos. Chem. Phys., 21, 1085–1104,Short summary
The characterization of particle emissions from aircraft is important for the assessment of the aviation impacts on climate and human health. We conducted field observations of aerosols near a runway at Narita International Airport in February 2018. We investigated particle number emissions from in-use commercial aircraft under real-world operating conditions, and we found the significance of sub-10 nm size ranges in take-off plumes for both total and non-volatile particles.
Jim M. Haywood, Steven J. Abel, Paul A. Barrett, Nicolas Bellouin, Alan Blyth, Keith N. Bower, Melissa Brooks, Ken Carslaw, Haochi Che, Hugh Coe, Michael I. Cotterell, Ian Crawford, Zhiqiang Cui, Nicholas Davies, Beth Dingley, Paul Field, Paola Formenti, Hamish Gordon, Martin de Graaf, Ross Herbert, Ben Johnson, Anthony C. Jones, Justin M. Langridge, Florent Malavelle, Daniel G. Partridge, Fanny Peers, Jens Redemann, Philip Stier, Kate Szpek, Jonathan W. Taylor, Duncan Watson-Parris, Robert Wood, Huihui Wu, and Paquita Zuidema
Atmos. Chem. Phys., 21, 1049–1084,Short summary
Every year, the seasonal cycle of biomass burning from agricultural practices in Africa creates a huge plume of smoke that travels many thousands of kilometres over the Atlantic Ocean. This study provides an overview of a measurement campaign called the cloud–aerosol–radiation interaction and forcing for year 2017 (CLARIFY-2017) and documents the rationale, deployment strategy, observations, and key results from the campaign which utilized the heavily equipped FAAM atmospheric research aircraft.
Huikun Liu, Qiyuan Wang, Li Xing, Yong Zhang, Ting Zhang, Weikang Ran, and Junji Cao
Atmos. Chem. Phys., 21, 973–987,Short summary
We conducted black carbon (BC) source apportionment on the southeastern Tibetan Plateau (TP) by an improved aethalometer model with the site-dependent Ångström exponent and BC mass absorption cross section (MAC). The result shows that the biomass-burning BC on the TP is slightly higher than fossil fuel BC, mainly from cross-border transportation instead of the local region, and the BC radiative effect is lower than that in the southwestern Himalaya but higher than that on the northeastern TP.
Vasiliki Daskalopoulou, Sotirios A. Mallios, Zbigniew Ulanowski, George Hloupis, Anna Gialitaki, Ioanna Tsikoudi, Konstantinos Tassis, and Vassilis Amiridis
Atmos. Chem. Phys., 21, 927–949,Short summary
This research highlights the detection of charged Saharan dust in Greece and provides indications of charge separation in the plumes through the first-ever co-located ground electric field measurements and sophisticated lidar observations. We provide a robust methodology for the extraction of a fair-weather proxy field used to assess the effect of lofted dust particles to the electric field and insert a realistic modelling aspect to the charge accumulation areas within electrically active dust.
Juha Sulo, Nina Sarnela, Jenni Kontkanen, Lauri Ahonen, Pauli Paasonen, Tiia Laurila, Tuija Jokinen, Juha Kangasluoma, Heikki Junninen, Mikko Sipilä, Tuukka Petäjä, Markku Kulmala, and Katrianne Lehtipalo
Atmos. Chem. Phys., 21, 695–715,Short summary
In this study, we analyzed over 5 years of sub-3 nm particle concentrations and their precursor vapors, identifying atmoshperic vapors important to the formation of these particles in the boreal forest. We also observed seasonal differences in both particle and precursor vapor concentrations and the formation pathways of these particles. Our results confirm the importance of organic vapors in atmospheric aerosol formation and highlight key seasonal differences that require further study.
Jinfeng Yuan, Robin Lewis Modini, Marco Zanatta, Andreas B. Herber, Thomas Müller, Birgit Wehner, Laurent Poulain, Thomas Tuch, Urs Baltensperger, and Martin Gysel-Beer
Atmos. Chem. Phys., 21, 635–655,Short summary
Black carbon (BC) aerosols contribute substantially to climate warming due to their unique light absorption capabilities. We performed field measurements at a central European background site in winter and found that variability in the absorption efficiency of BC particles is driven mainly by their internal mixing state. Our results suggest that, at this site, knowing the BC mixing state is sufficient to describe BC light absorption enhancements due to the lensing effect in good approximation.
Shuo Ding, Dantong Liu, Kang Hu, Delong Zhao, Ping Tian, Fei Wang, Ruijie Li, Yichen Chen, Hui He, Mengyu Huang, and Deping Ding
Atmos. Chem. Phys., 21, 681–694,Short summary
In this study, we for the first time characterized the detailed black carbon (BC) microphysics at a mountain site located at the top of the planetary boundary layer (PBL) influenced by surface emission over the North China Plain. We investigated the optical and hygroscopic properties of BC at this level as influenced by microphysical properties. Such information will constrain the impacts of BC in influencing the PBL dynamics and low-level cloud formation over anthropogenically polluted regions.
David Brus, Jani Gustafsson, Ville Vakkari, Osku Kemppinen, Gijs de Boer, and Anne Hirsikko
Atmos. Chem. Phys., 21, 517–533,Short summary
This paper summarizes Finnish Meteorological Institute and Kansas State University unmanned aerial vehicle measurements during the summer 2018 Lower Atmospheric Process Studies at Elevation – a Remotely-piloted Aircraft Team Experiment (LAPSE-RATE) campaign in the San Luis Valley, providing an overview of the rotorcraft deployed, payloads, scientific goals and flight strategies and presenting observations of atmospheric thermodynamics and aerosol and gas parameters in the vertical column.
Jesús Yus-Díez, Marina Ealo, Marco Pandolfi, Noemí Perez, Gloria Titos, Griša Močnik, Xavier Querol, and Andrés Alastuey
Atmos. Chem. Phys., 21, 431–455,Short summary
Here we describe the vertical profiles of extensive (scattering and absorption) and intensive (e.g. albedo and asymmetry parameter) aerosol optical properties from coupling ground-based measurements from two sites in north-eastern Spain and airborne measurements performed with an aircraft. We analyse different aerosol layers along the vertical profile for a regional pollution episode and a Saharan dust intrusion. The results show a change with height depending on the different measured layers.
Carolina Ramírez-Romero, Alejandro Jaramillo, María F. Córdoba, Graciela B. Raga, Javier Miranda, Harry Alvarez-Ospina, Daniel Rosas, Talib Amador, Jong Sung Kim, Jacqueline Yakobi-Hancock, Darrel Baumgardner, and Luis A. Ladino
Atmos. Chem. Phys., 21, 239–253,Short summary
Field measurements were conducted to confirm the arrival of African dust on the Yucatàn Peninsula. Aerosol particles were monitored at ground level by different online and off-line sensors. Several particulate matter peaks were observed with a relative increase in their levels of up to 500 % with respect to background conditions. Based on the chemical composition, back trajectories, vertical profiles, reanalysis, and satellite images, it was found that the peaks are linked to African dust.
Rutambhara Joshi, Dantong Liu, Eiko Nemitz, Ben Langford, Neil Mullinger, Freya Squires, James Lee, Yunfei Wu, Xiaole Pan, Pingqing Fu, Simone Kotthaus, Sue Grimmond, Qiang Zhang, Ruili Wu, Oliver Wild, Michael Flynn, Hugh Coe, and James Allan
Atmos. Chem. Phys., 21, 147–162,Short summary
Black carbon (BC) is a component of particulate matter which has significant effects on climate and human health. Sources of BC include biomass burning, transport, industry and domestic cooking and heating. In this study, we measured BC emissions in Beijing, finding a dominance of traffic emissions over all other sources. The quantitative method presented here has benefits for revising widely used emissions inventories and for understanding BC sources with impacts on air quality and climate.
Joseph Ko, Trevor Krasowsky, and George Ban-Weiss
Atmos. Chem. Phys., 20, 15635–15664,Short summary
Black carbon (BC) is the second strongest climate forcing pollutant in the atmosphere, after carbon dioxide. Here, we seek to understand how BC microphysical properties vary with atmospheric contexts, as these properties can influence its radiative forcing. Consistent with previous studies, we found that biomass burning BC had thicker coatings and larger core diameters than fossil fuel BC. We also present evidence to show that atmospheric aging also increases BC coating thickness.
Imre Salma, Máté Vörösmarty, András Zénó Gyöngyösi, Wanda Thén, and Tamás Weidinger
Atmos. Chem. Phys., 20, 15725–15742,Short summary
Motor vehicle road traffic in Budapest was reduced by approximately 50% of its ordinary level due to COVID-19. In parallel, concentrations of most criteria air pollutants declined by 30–60%. Change rates of NO and NO2 with relative change in traffic intensity were the largest, total particle number concentration showed considerable dependency, while particulate matter mass concentrations did not appear to be related to urban traffic. Concentrations of O3 showed an increasing tendency.
Qiyuan Wang, Li Li, Jiamao Zhou, Jianhuai Ye, Wenting Dai, Huikun Liu, Yong Zhang, Renjian Zhang, Jie Tian, Yang Chen, Yunfei Wu, Weikang Ran, and Junji Cao
Atmos. Chem. Phys., 20, 15427–15442,Short summary
Recently, China has promulgated a series of regulations to reduce air pollutants. The decreased black carbon (BC) and co-emitted pollutants could affect the interactions between BC and other aerosols, which in turn results in changes in BC. Herein, we re-assessed the characteristics of BC of a representative pollution site in northern China in the final year of the Chinese
Action Plan for the Prevention and Control of Air Pollution.
Agnieszka Kupc, Christina J. Williamson, Anna L. Hodshire, Jan Kazil, Eric Ray, T. Paul Bui, Maximilian Dollner, Karl D. Froyd, Kathryn McKain, Andrew Rollins, Gregory P. Schill, Alexander Thames, Bernadett B. Weinzierl, Jeffrey R. Pierce, and Charles A. Brock
Atmos. Chem. Phys., 20, 15037–15060,Short summary
Tropical upper troposphere over the Atlantic and Pacific oceans is a major source region of new particles. These particles are associated with the outflow from deep convection. We investigate the processes that govern the formation of these particles and their initial growth and show that none of the formation schemes commonly used in global models are consistent with observations. Using newer schemes indicates that organic compounds are likely important as nucleating and initial growth agents.
Yuan Wang, Xiaojian Zheng, Xiquan Dong, Baike Xi, Peng Wu, Timothy Logan, and Yuk L. Yung
Atmos. Chem. Phys., 20, 14741–14755,Short summary
A recent aircraft field campaign near the Azores in the summer of 2017 provides ample observations of aerosols and clouds with detailed vertical information. This study utilizes those observational data in combination with the aerosol-aware large-eddy simulations and aerosol reanalysis data to examine the significance of the long-range-transported aerosol effect on marine-boundary-layer clouds. It is the first time that the ACE-ENA aircraft campaign data are used for this topic.
Imre Salma, Wanda Thén, Pasi Aalto, Veli-Matti Kerminen, Anikó Kern, Zoltán Barcza, Tuukka Petäjä, and Markku Kulmala
Atmos. Chem. Phys. Discuss.,
Revised manuscript accepted for ACPShort summary
The distribution of monthly mean nucleation frequency possessed a characteristic pattern. Its shape was compared to those of environmental variables including vegetation-derived properties. The spring maximum in the occurrence frequency often overlapped with the positive T anomaly. The link between the heat stress and the occurrence minimum in summer could not be proved, while association between the occurrence frequency and vegetation growth dynamics was clearly identified in spring.
Douglas Morrison, Ian Crawford, Nicholas Marsden, Michael Flynn, Katie Read, Luis Neves, Virginia Foot, Paul Kaye, Warren Stanley, Hugh Coe, David Topping, and Martin Gallagher
Atmos. Chem. Phys., 20, 14473–14490,Short summary
We provide conservative estimates of the concentrations of bacteria within transatlantic dust clouds, originating from the African continent. We observe significant seasonal differences in the overall concentrations of particles but no seasonal variation in the ratio between bacteria and dust. With bacteria contributing to ice formation at warmer temperatures than dust, our observations should improve the accuracy of climate models.
Juan Andrés Casquero-Vera, Hassan Lyamani, Lubna Dada, Simo Hakala, Pauli Paasonen, Roberto Román, Roberto Fraile, Tuukka Petäjä, Francisco José Olmo-Reyes, and Lucas Alados-Arboledas
Atmos. Chem. Phys., 20, 14253–14271,Short summary
New particle formation was investigated at two stations located close to each other but at different altitudes: urban and high-altitude sites. Results show that sulfuric acid is able to explain a minimal fraction contribution to the observed growth rates and point to the availability of volatile organic compounds as the main factor controlling NPF events at both sites. A closer analysis of the NPF events that were observed at high-altitude sites during a Saharan dust episode was carried out.
Junfeng Wang, Jianhuai Ye, Dantong Liu, Yangzhou Wu, Jian Zhao, Weiqi Xu, Conghui Xie, Fuzhen Shen, Jie Zhang, Paul E. Ohno, Yiming Qin, Xiuyong Zhao, Scot T. Martin, Alex K. Y. Lee, Pingqing Fu, Daniel J. Jacob, Qi Zhang, Yele Sun, Mindong Chen, and Xinlei Ge
Atmos. Chem. Phys., 20, 14091–14102,Short summary
We compared the organics in total submicron matter and those coated on BC cores during summertime in Beijing and found large differences between them. Traffic-related OA was associated significantly with BC, while cooking-related OA did not coat BC. In addition, a factor likely originated from primary biomass burning OA was only identified in BC-containing particles. Such a unique BBOA requires further field and laboratory studies to verify its presence and elucidate its properties and impacts.
Qiaoyun Hu, Haofei Wang, Philippe Goloub, Zhengqiang Li, Igor Veselovskii, Thierry Podvin, Kaitao Li, and Mikhail Korenskiy
Atmos. Chem. Phys., 20, 13817–13834,Short summary
This study presents the characteristics of Taklamakan dust particles derived from lidar measurements collected in the dust aerosol observation field campaign. It provides comprehensive parameters for Taklamakan dust properties and vertical distributions of Taklamakan dust. This paper also points out the importance of polluted dust which was frequently observed in the field campaign. The results contribute to improving knowledge about dust and reducing uncertainties in the climatic model.
Dominic Heslin-Rees, Maria Burgos, Hans-Christen Hansson, Radovan Krejci, Johan Ström, Peter Tunved, and Paul Zieger
Atmos. Chem. Phys., 20, 13671–13686,Short summary
Aerosol particles are one important key player in the Arctic climate. Using long-term measurements of particle light scattering from an observatory on Svalbard, this study investigates the reasons behind an observed shift towards larger particles seen in the last 2 decades. We find that increases in sea spray are the most likely cause. Air masses from the south-west have increased significantly, suggestive of a potential mechanism, whilst the retreat in sea ice has a marginal influence.
Haebum Lee, Kwangyul Lee, Chris Rene Lunder, Radovan Krejci, Wenche Aas, Jiyeon Park, Ki-Tae Park, Bang Yong Lee, Young Jun Yoon, and Kihong Park
Atmos. Chem. Phys., 20, 13425–13441,Short summary
New particle formation (NPF) contributes to enhance the number of particles in the ambient atmosphere, affecting local air quality and cloud condensation nuclei (CCN) concentration. This study investigated NPF characteristics in the Arctic and showed that although formation and growth rates of nanoparticles were much lower than those in continental areas, NPF occurrence frequency was comparable and marine biogenic sources played important roles in production of condensing vapors for NPF.
Lawrence I. Kleinman, Arthur J. Sedlacek III, Kouji Adachi, Peter R. Buseck, Sonya Collier, Manvendra K. Dubey, Anna L. Hodshire, Ernie Lewis, Timothy B. Onasch, Jeffery R. Pierce, John Shilling, Stephen R. Springston, Jian Wang, Qi Zhang, Shan Zhou, and Robert J. Yokelson
Atmos. Chem. Phys., 20, 13319–13341,Short summary
Aerosols from wildfires affect the Earth's temperature by absorbing light or reflecting it back into space. This study investigates time-dependent chemical, microphysical, and optical properties of aerosols generated by wildfires in the Pacific Northwest, USA. Wildfire smoke plumes were traversed by an instrumented aircraft at locations near the fire and up to 3.5 h travel time downwind. Although there was no net aerosol production, aerosol particles grew and became more efficient scatters.
Pengguo Zhao, Zhanqing Li, Hui Xiao, Fang Wu, Youtong Zheng, Maureen C. Cribb, Xiaoai Jin, and Yunjun Zhou
Atmos. Chem. Phys., 20, 13379–13397,Short summary
We discussed the different aerosol effects on lightning in plateau and basin regions of Sichuan, southwestern China. In the plateau area, the aerosol concentration is low, and aerosols (via microphysical effects) inhibit the process of warm rain and stimulate convection and lightning activity. In the basin region, however, aerosols tend to show a significant radiative effect (reducing the solar radiation reaching the surface by absorbing and scattering) and inhibit the lightning.
Ying Zhu, Jia Chen, Xiao Bi, Gerrit Kuhlmann, Ka Lok Chan, Florian Dietrich, Dominik Brunner, Sheng Ye, and Mark Wenig
Atmos. Chem. Phys., 20, 13241–13251,Short summary
Average NO2 concentration of on-street mobile measurements (MMs) near the monitoring stations (MSs) was found to be considerably higher than the MSs data. The common measurement height (H) and distance (D) of the MSs result in 27 % lower average concentrations in total than the concentration of our MMs. Another 21 % difference remained after correcting the influence of the measuring H and D. This result makes our city-wide measurements for capturing the full range of concentrations necessary.
Huihui Wu, Jonathan W. Taylor, Kate Szpek, Justin M. Langridge, Paul I. Williams, Michael Flynn, James D. Allan, Steven J. Abel, Joseph Pitt, Michael I. Cotterell, Cathryn Fox, Nicholas W. Davies, Jim Haywood, and Hugh Coe
Atmos. Chem. Phys., 20, 12697–12719,Short summary
Airborne measurements of highly aged biomass burning aerosols (BBAs) over the remote southeast Atlantic provide unique aerosol parameters for climate models. Our observations demonstrate the persistence of strongly absorbing BBAs across wide regions of the South Atlantic. We also found significant vertical variation in the single-scattering albedo of these BBAs, as a function of relative chemical composition and size. Aerosol properties in the marine BL are suggested to be separated from the FT.
Guangjie Zheng, Chongai Kuang, Janek Uin, Thomas Watson, and Jian Wang
Atmos. Chem. Phys., 20, 12515–12525,Short summary
Condensational growth of Aitken-mode particles is a major source of cloud condensation nuclei in the remote marine boundary layer. It has been long thought that over remote oceans, condensation growth is dominated by sulfate that derives from ocean-emitted dimethyl sulfide. In this study, we present the first long-term observational evidence that, contrary to conventional thinking, organics play an even more important role than sulfate in particle growth over remote oceans throughout the year.
Santtu Mikkonen, Zoltán Németh, Veronika Varga, Tamás Weidinger, Ville Leinonen, Taina Yli-Juuti, and Imre Salma
Atmos. Chem. Phys., 20, 12247–12263,Short summary
We determined decennial statistical time trends and diurnal statistical patterns of atmospheric particle number concentrations in various relevant size fractions in the city centre of Budapest in an interval of 2008–2018. The mean overall decrease rate of particles in different size fractions was approximately −5 % scaled for the 10-year measurement interval. The decline can be interpreted as a consequence of the decreased anthropogenic emissions in the city.
Yijia Zhang, Zhicong Yin, and Huijun Wang
Atmos. Chem. Phys., 20, 12211–12221,Short summary
Haze events in early winter in North China exhibited rapid growth after 2010, which was completely different from the slow decline observed before 2010. However, global warming and anthropogenic emissions could not explain this trend reversal well, which was puzzling. Our study found that four climate factors, exhibiting completely opposite trends before and after 2010, effectively drove the trend reversal of the haze pollution in North China.
Aikaterini Bougiatioti, Athanasios Nenes, Jack J. Lin, Charles A. Brock, Joost A. de Gouw, Jin Liao, Ann M. Middlebrook, and André Welti
Atmos. Chem. Phys., 20, 12163–12176,Short summary
The number concentration of droplets in clouds in the summertime in the southeastern United States is influenced by aerosol variations but limited by the strong competition for supersaturated water vapor. Concurrent variations in vertical velocity magnify the response of cloud droplet number to aerosol increases by up to a factor of 5. Omitting the covariance of vertical velocity with aerosol number may therefore bias estimates of the cloud albedo effect from aerosols.
Janne Lampilahti, Hanna Elina Manninen, Katri Leino, Riikka Väänänen, Antti Manninen, Stephany Buenrostro Mazon, Tuomo Nieminen, Matti Leskinen, Joonas Enroth, Marja Bister, Sergej Zilitinkevich, Juha Kangasluoma, Heikki Järvinen, Veli-Matti Kerminen, Tuukka Petäjä, and Markku Kulmala
Atmos. Chem. Phys., 20, 11841–11854,Short summary
In this work, by using co-located airborne and ground-based measurements, we show that counter-rotating horizontal circulations in the planetary boundary layer (roll vortices) frequently enhance regional new particle formation or induce localized bursts of new particle formation. These observations can be explained by the ability of the rolls to efficiently lift low-volatile vapors emitted from the surface to the top of the boundary layer where new particle formation is more favorable.
Jonas Svensson, Johan Ström, Henri Honkonen, Eija Asmi, Nathaniel B. Dkhar, Shresth Tayal, Ved P. Sharma, Rakesh Hooda, Matti Leppäranta, Hans-Werner Jacobi, Heikki Lihavainen, and Antti Hyvärinen
Atmos. Chem. Phys. Discuss.,
Preprint under review for ACPShort summary
Light-absorbing particles specifically affect snow melt in the Himalaya. Through measurements of the constituents in glacier snow pits from Indian Himalaya our investigations show that different snow layers display striking similarities. These similarities can be characterized by a deposition constant. Our results further indicate that mineral dust can be responsible for the majority of light absorption in the snow in this part of the Himalaya.
Shaoxiang Ma, He Cheng, Jiacheng Li, Maoyuan Xu, Dawei Liu, and Kostya Ostrikov
Atmos. Chem. Phys., 20, 11717–11727,Short summary
Our work suggests that a large corona discharge system is an efficient and possibly economically sustainable way to increase the ion density in the open air and control the precipitation of atmospheric aerosols. Once the system is installed on a mountaintop, it will generate lots of charged nuclei, which may trigger water precipitation or fog elimination within a certain region in the downwind directions.
Antonios Tasoglou, Evangelos Louvaris, Kalliopi Florou, Aikaterini Liangou, Eleni Karnezi, Christos Kaltsonoudis, Ningxin Wang, and Spyros N. Pandis
Atmos. Chem. Phys., 20, 11625–11637,Short summary
A month-long set of summertime measurements in a remote area in the Mediterranean is used to quantify aerosol absorption. The measured light absorption was two or more times higher than that of fresh black carbon. The absorption enhancement due to the coating of black carbon cores by other aerosol components could explain only part of this absorption enhancement. The rest was due to brown carbon, mostly in the form of extremely low volatility organic compounds.
Jenni Kontkanen, Chenjuan Deng, Yueyun Fu, Lubna Dada, Ying Zhou, Jing Cai, Kaspar R. Daellenbach, Simo Hakala, Tom V. Kokkonen, Zhuohui Lin, Yongchun Liu, Yonghong Wang, Chao Yan, Tuukka Petäjä, Jingkun Jiang, Markku Kulmala, and Pauli Paasonen
Atmos. Chem. Phys., 20, 11329–11348,Short summary
To estimate the impacts of atmospheric aerosol particles on air quality, knowledge of size distributions of particles emitted from anthropogenic sources is needed. We introduce a new method for determining size-resolved particle number emissions from measured particle size distributions. We apply our method to data measured in Beijing, China. We find that particle number emissions at our site are dominated by emissions of particles smaller than 30 nm, originating mainly from traffic.
Sami Seppälä, Joel Kuula, Antti-Pekka Hyvärinen, Sanna Saarikoski, Topi Rönkkö, Jorma Keskinen, Jukka-Pekka Jalkanen, and Hilkka Timonen
Atmos. Chem. Phys. Discuss.,
Revised manuscript accepted for ACPShort summary
Effects of fuel sulfur content restrictions implemented by the International Maritime Organization at the Baltic Sea, in July 2010 and January 2015, on the particle properties of ship exhaust plumes and ambient aerosol were studied. The restrictions reduced the particle number concentrations and median particle size in plumes and number concentrations in the ambient aerosol. These changes may improve human health in coastal areas and decrease the cooling effect of the exhaust emissions of ships.
Yohei Shinozuka, Meloë S. Kacenelenbogen, Sharon P. Burton, Steven G. Howell, Paquita Zuidema, Richard A. Ferrare, Samuel E. LeBlanc, Kristina Pistone, Stephen Broccardo, Jens Redemann, K. Sebastian Schmidt, Sabrina P. Cochrane, Marta Fenn, Steffen Freitag, Amie Dobracki, Michal Segal-Rosenheimer, and Connor J. Flynn
Atmos. Chem. Phys., 20, 11275–11285,Short summary
To help satellite retrieval of aerosols and studies of their radiative effects, we demonstrate that daytime aerosol optical depth over low-level clouds is similar to that in neighboring clear skies at the same heights. Based on recent airborne lidar and sun photometer observations above the southeast Atlantic, the mean AOD difference at 532 nm is between 0 and -0.01, when comparing the cloudy and clear sides of cloud edges, with each up to 20 km wide.
Jonathan W. Taylor, Huihui Wu, Kate Szpek, Keith Bower, Ian Crawford, Michael J. Flynn, Paul I. Williams, James Dorsey, Justin M. Langridge, Michael I. Cotterell, Cathryn Fox, Nicholas W. Davies, Jim M. Haywood, and Hugh Coe
Atmos. Chem. Phys., 20, 11201–11221,Short summary
Every year, huge plumes of smoke hundreds of miles wide travel over the south Atlantic Ocean from fires in central and southern Africa. These plumes absorb the sun’s energy and warm the climate. We used airborne optical instrumentation to determine how absorbing the smoke was as well as the relative importance of black and brown carbon. We also tested different ways of simulating these properties that could be used in a climate model.
Jost Heintzenberg, Wolfram Birmili, Bryan Hellack, Gerald Spindler, Thomas Tuch, and Alfred Wiedensohler
Atmos. Chem. Phys., 20, 10967–10984,Short summary
A total of 10 years of hourly aerosol and gas data at four rural German stations have been combined with hourly back trajectories to the stations and inventories of the European Emissions Database for Global Atmospheric Research (EDGAR), yielding emission maps and trends over Germany for PM10, particle number concentrations, and equivalent black carbon (eBC). The maps reflect aerosol emissions modified with atmospheric processes during transport between sources and receptor sites.
Kevin J. Sanchez, Gregory C. Roberts, Georges Saliba, Lynn M. Russell, Cynthia Twohy, Michael J. Reeves, Ruhi S. Humphries, Melita D. Keywood, Jason P. Ward, and Ian M. McRobert
Atmos. Chem. Phys. Discuss.,
Revised manuscript accepted for ACPShort summary
Measurements of particles and their properties were made from aircraft over the Southern Ocean. Aerosol transported from the Antarctic coast is shown to greatly enhances the particle concentrations over the Southern Ocean. The occurrence of precipitation was shown to be associated with the lowest particle concentrations over the Southern Ocean. These particles are important due to their ability to enhance cloud droplet concentrations, resulting in more sunlight being reflected by the clouds.
Xiaoyan Wang, Renhe Zhang, Yanke Tan, and Wei Yu
Atmos. Chem. Phys. Discuss.,
Revised manuscript accepted for ACPShort summary
The physical mechanism of synoptic patterns affecting the decay process of air pollution episodes are investigate in this work. Three dominate circulation pattern are identified, which usually decrease the ambient PM2.5 concentrations by 27 %~ 41 % after they arrived around Beijing. Emission reductions led to a 4.3~5.7 μg/(m3.yr) decrease in PM2.5 concentrations around Beijing during 2014 to 2020.
W. Richard Leaitch, John K. Kodros, Megan D. Willis, Sarah Hanna, Hannes Schulz, Elisabeth Andrews, Heiko Bozem, Julia Burkart, Peter Hoor, Felicia Kolonjari, John A. Ogren, Sangeeta Sharma, Meng Si, Knut von Salzen, Allan K. Bertram, Andreas Herber, Jonathan P. D. Abbatt, and Jeffrey R. Pierce
Atmos. Chem. Phys., 20, 10545–10563,Short summary
Black carbon is a factor in the warming of the Arctic atmosphere due to its ability to absorb light, but the uncertainty is high and few observations have been made in the high Arctic above 80° N. We combine airborne and ground-based observations in the springtime Arctic, at and above 80° N, with simulations from a global model to show that light absorption by black carbon may be much larger than modelled. However, the uncertainty remains high.
Xiaochao Yu, Zhili Wang, Hua Zhang, Jianjun He, and Ying Li
Atmos. Chem. Phys., 20, 10279–10293,Short summary
There are statistically significant positive and negative correlations, respectively, between winter haze days (WHDs) in China's Jing-Jin-Ji region and eastern Pacific and central Pacific El Niño events. These opposite changes in WHDs are attributable to the anomalies of both large-scale circulation and local synoptic conditions corresponding to two types of El Niño. Our study highlights the importance of distinguishing the impacts of two types of El Niño on winter haze pollution in this region.
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We analyze seasonal and diurnal concentrations of black carbon (BC), ozone, and associated meteorological conditions within a remote trans-Himalayan valley in western Nepal. We observe elevated BC concentrations during non-monsoon seasons, frequent and persistent episodes of higher-than-average concentrations, and net up-valley fluxes throughout the year. The findings provide direct observational evidence of trans-Himalayan valleys serving as vital pollutant transport pathways.
We analyze seasonal and diurnal concentrations of black carbon (BC), ozone, and associated...