Articles | Volume 18, issue 7
10 Apr 2018
Research article | 10 Apr 2018
On the functional form of particle number size distributions: influence of particle source and meteorological variables
Katia Cugerone et al.
No articles found.
Greta Cazzaniga, Carlo De Michele, Michele D'Amico, Cristina Deidda, Antonio Ghezzi, and Roberto Nebuloni
Hydrol. Earth Syst. Sci., 26, 2093–2111,Short summary
Rainfall estimates are usually obtained from rain gauges, weather radars, or satellites. An alternative is the measurement of the signal loss induced by rainfall on commercial microwave links (CMLs). In this work, we assess the hydrologic response of Lambro Basin when CML-retrieved rainfall is used as model input. CML estimates agree with rain gauge data. CML-driven discharge simulations show performance comparable to that from rain gauges if a CML-based calibration of the model is undertaken.
Fabiola Banfi and Carlo De Michele
The Cryosphere, 16, 1031–1056,Short summary
Climate changes require a dynamic description of glaciers in hydrological models. In this study we focus on the local modelling of snow and firn. We tested our model at the site of Colle Gnifetti, 4400–4550 m a.s.l. The model shows that wind erodes all the precipitation of the cold months, while snow is in part conserved between April and September since higher temperatures protect snow from erosion. We also compared modelled and observed firn density, obtaining a satisfying agreement.
Julia Schmale, Sangeeta Sharma, Stefano Decesari, Jakob Pernov, Andreas Massling, Hans-Christen Hansson, Knut von Salzen, Henrik Skov, Elisabeth Andrews, Patricia K. Quinn, Lucia M. Upchurch, Konstantinos Eleftheriadis, Rita Traversi, Stefania Gilardoni, Mauro Mazzola, James Laing, and Philip Hopke
Atmos. Chem. Phys., 22, 3067–3096,Short summary
Long-term data sets of Arctic aerosol properties from 10 stations across the Arctic provide evidence that anthropogenic influence on the Arctic atmospheric chemical composition has declined in winter, a season which is typically dominated by mid-latitude emissions. The number of significant trends in summer is smaller than in winter, and overall the pattern is ambiguous with some significant positive and negative trends. This reflects the mixed influence of natural and anthropogenic emissions.
Congbo Song, Manuel Dall'Osto, Angelo Lupi, Mauro Mazzola, Rita Traversi, Silvia Becagli, Stefania Gilardoni, Stergios Vratolis, Karl Espen Yttri, David C. S. Beddows, Julia Schmale, James Brean, Agung Ghani Kramawijaya, Roy M. Harrison, and Zongbo Shi
Atmos. Chem. Phys., 21, 11317–11335,Short summary
We present a cluster analysis of relatively long-term (2015–2019) aerosol aerodynamic volume size distributions up to 20 μm in the Arctic for the first time. The study found that anthropogenic and natural aerosols comprised 27 % and 73 % of the occurrence of the coarse-mode aerosols, respectively. Our study shows that about two-thirds of the coarse-mode aerosols are related to two sea-spray-related aerosol clusters, indicating that sea spray aerosol may more complex in the Arctic environment.
Roberto Villalobos-Herrera, Emanuele Bevacqua, Andreia F. S. Ribeiro, Graeme Auld, Laura Crocetti, Bilyana Mircheva, Minh Ha, Jakob Zscheischler, and Carlo De Michele
Nat. Hazards Earth Syst. Sci., 21, 1867–1885,Short summary
Climate hazards may be caused by events which have multiple drivers. Here we present a method to break down climate model biases in hazard indicators down to the bias caused by each driving variable. Using simplified fire and heat stress indicators driven by temperature and relative humidity as examples, we show how multivariate indicators may have complex biases and that the relationship between driving variables is a source of bias that must be considered in climate model bias corrections.
Jianhui Jiang, Imad El Haddad, Sebnem Aksoyoglu, Giulia Stefenelli, Amelie Bertrand, Nicolas Marchand, Francesco Canonaco, Jean-Eudes Petit, Olivier Favez, Stefania Gilardoni, Urs Baltensperger, and André S. H. Prévôt
Geosci. Model Dev., 14, 1681–1697,Short summary
We developed a box model with a volatility basis set to simulate organic aerosol (OA) from biomass burning and optimized the vapor-wall-loss-corrected OA yields with a genetic algorithm. The optimized parameterizations were then implemented in the air quality model CAMx v6.5. Comparisons with ambient measurements indicate that the vapor-wall-loss-corrected parameterization effectively improves the model performance in predicting OA, which reduced the mean fractional bias from −72.9 % to −1.6 %.
Marco Bongio, Ali Nadir Arslan, Cemal Melih Tanis, and Carlo De Michele
The Cryosphere, 15, 369–387,Short summary
The capability of time-lapse photography to retrieve snow depth time series was tested. We demonstrated that this method can be efficiently used in three different case studies: two in the Italian Alps and one in a forested region of Finland, with an accuracy comparable to the most common methods such as ultrasonic sensors or manual measurements. We hope that this simple method based only on a camera and a graduated stake can enable snow depth measurements in dangerous and inaccessible sites.
Fabiola Banfi and Carlo De Michele
The Cryosphere Discuss.,
Manuscript not accepted for further reviewShort summary
Climate changes require a dynamic description of glaciers in hydrological models. In this study we focus on the local modeling of snow and firn. We tested our model at the site of Colle Gnifetti, 4400–4550 m a.s.l. The model shows that wind erodes all the precipitation of the cold months, while snow is in part conserved between May and September, since higher temperatures protect snow from erosion. We also compared modeled and observed firn density obtaining a satisfying agreement.
Marco Paglione, Stefania Gilardoni, Matteo Rinaldi, Stefano Decesari, Nicola Zanca, Silvia Sandrini, Lara Giulianelli, Dimitri Bacco, Silvia Ferrari, Vanes Poluzzi, Fabiana Scotto, Arianna Trentini, Laurent Poulain, Hartmut Herrmann, Alfred Wiedensohler, Francesco Canonaco, André S. H. Prévôt, Paola Massoli, Claudio Carbone, Maria Cristina Facchini, and Sandro Fuzzi
Atmos. Chem. Phys., 20, 1233–1254,Short summary
Our multi-year observational study regarding organic aerosol (OA) in the Po Valley indicates that more than half of OA is of secondary origin (SOA) through all the year and at both urban and rural sites. Within the SOA, the measurements show the importance of biomass burning (BB) aging products during cold seasons and indicate aqueous-phase processing of BB emissions as a fundamental driver of SOA formation in wintertime, with important consequences for air quality policy at the global level.
Jianhui Jiang, Sebnem Aksoyoglu, Imad El-Haddad, Giancarlo Ciarelli, Hugo A. C. Denier van der Gon, Francesco Canonaco, Stefania Gilardoni, Marco Paglione, María Cruz Minguillón, Olivier Favez, Yunjiang Zhang, Nicolas Marchand, Liqing Hao, Annele Virtanen, Kalliopi Florou, Colin O'Dowd, Jurgita Ovadnevaite, Urs Baltensperger, and André S. H. Prévôt
Atmos. Chem. Phys., 19, 15247–15270,Short summary
We use an air quality model with a modified organic aerosol (OA) module based on chamber experiments to identify the OA sources and their contributions in Europe. Comparisons with long-term measurements at nine sites in 2011 show an improvement in OA simulation. Our results suggest that the biomass burning and biogenic emissions are the dominant sources in winter and summer, respectively. Contributions of diesel and gasoline vehicles are relatively small compared to a previous study in the US.
Matthew Brege, Marco Paglione, Stefania Gilardoni, Stefano Decesari, Maria Cristina Facchini, and Lynn R. Mazzoleni
Atmos. Chem. Phys., 18, 13197–13214,Short summary
The detailed molecular composition of ambient fog and aerosol influenced by regional biomass burning and secondary processes was studied. Aerosol and aqueous-phase functionalization and oxidation were observed, leading to fog compositions that are more "SOA-like" than aerosols. The significance of the aqueous phase in transforming the molecular chemistry and contributing to secondary organic aerosol is demonstrated here.
Nicola Zanca, Andrew T. Lambe, Paola Massoli, Marco Paglione, David R. Croasdale, Yatish Parmar, Emilio Tagliavini, Stefania Gilardoni, and Stefano Decesari
Atmos. Chem. Phys., 17, 10405–10421,Short summary
Simulating the composition of organic aerosol particles formed by chemical reactions in the atmosphere (secondary organic aerosol, SOA) is challenged by the enormous complexity of molecular species and chemical processes involved. We report spectroscopic (NMR) and chromatographic data for SOA samples obtained using a flow reactor designed to simulate photochemical ageing. We show that the composition of aged biogenic (monoterpene) SOA particles closely resembles that of ambient aerosols.
Stefano Decesari, Mohammad Hossein Sowlat, Sina Hasheminassab, Silvia Sandrini, Stefania Gilardoni, Maria Cristina Facchini, Sandro Fuzzi, and Constantinos Sioutas
Atmos. Chem. Phys., 17, 7721–7731,Short summary
Exposure to atmospheric particulate matter (PM) represents one of the biggest environmental health risks. We show that the intrinsic PM toxicity at a rural site, far from traffic emissions, is comparable to that of urban areas heavily impacted by traffic. Potentially toxic, redox-active compounds in PM are efficiently scavenged in the presence of fog but are also produced in fog. These findings provide evidence that atmospheric processing can significantly alter the toxicity of airborne PM.
Francesco Avanzi, Alberto Bianchi, Alberto Cina, Carlo De Michele, Paolo Maschio, Diana Pagliari, Daniele Passoni, Livio Pinto, Marco Piras, and Lorenzo Rossi
The Cryosphere Discuss.,
Revised manuscript not acceptedShort summary
We compare three different instruments used to collect snow depth, i.e., photogrammetric surveys using Unmanned Aerial Systems (UAS), a 3D laser scanning, and manual probing. The relatively high density of manual data (135 pt over 6700 m2, i.e., 2 pt/100 m2) enables to assess the performance of UAS in capturing the marked spatial variability of snow. Results suggest that UAS represent a competitive choice among existing techniques for high-precision, high-resolution remote sensing of snow.
Evangelia Diapouli, Manousos I. Manousakas, Stergios Vratolis, Vasiliki Vasilatou, Stella Pateraki, Kyriaki A. Bairachtari, Xavier Querol, Fulvio Amato, Andrés Alastuey, Angeliki A. Karanasiou, Franco Lucarelli, Silvia Nava, Giulia Calzolai, Vorne L. Gianelle, Cristina Colombi, Célia Alves, Danilo Custódio, Casimiro Pio, Christos Spyrou, George B. Kallos, and Konstantinos Eleftheriadis
Atmos. Chem. Phys., 17, 3673–3685,Short summary
This study examined the contribution of two natural sources (long-range transport of African dust and sea salt) to the airborne particulate matter concentrations, in 5 southern European cities (Porto, Barcelona, Milan, Florence, Athens). The results demonstrated that natural sources are often expressed with high-intensity events, leading even to exceedances of the EU air quality standards. This effect was more pronounced in the case of African dust intrusions in the eastern Mediterranean area.
Francesca Costabile, Stefania Gilardoni, Francesca Barnaba, Antonio Di Ianni, Luca Di Liberto, Davide Dionisi, Maurizio Manigrasso, Marco Paglione, Vanes Poluzzi, Matteo Rinaldi, Maria Cristina Facchini, and Gian Paolo Gobbi
Atmos. Chem. Phys., 17, 313–326,Short summary
We investigate the particle size distribution and spectral optical properties of brown carbon (BrC) associated with the formation of secondary aerosol in the ambient atmosphere and relate these properties to major aerosol chemical components. We found that BrC occurs in particles in the droplet mode size range, enriched in ammonium nitrate and poor in black carbon (BC), with a strong dependance on the organic aerosol to BC ratio.
Francesco Avanzi, Hiroyuki Hirashima, Satoru Yamaguchi, Takafumi Katsushima, and Carlo De Michele
The Cryosphere, 10, 2013–2026,Short summary
We investigate capillary barriers and preferential flow in layered snow during nine cold laboratory experiments. The dynamics of each sample were replicated solving Richards equation within the 1-D multi-layer physically based SNOWPACK model. Results show that both processes affect the speed of water infiltration in stratified snow and are marked by a high degree of spatial variability at cm scale and complex 3-D patterns.
Silvia Sandrini, Dominik van Pinxteren, Lara Giulianelli, Hartmut Herrmann, Laurent Poulain, Maria Cristina Facchini, Stefania Gilardoni, Matteo Rinaldi, Marco Paglione, Barbara J. Turpin, Francesca Pollini, Silvia Bucci, Nicola Zanca, and Stefano Decesari
Atmos. Chem. Phys., 16, 10879–10897,Short summary
This paper deals with impactor measurements performed in the summer 2012 during the EU project PEGASOS campaign in the Po Valley, at an urban and a rural site. The paper tries to disentangle the effects of weather anomalies (temporal and spatial) from those of diverse emissions (NH3) and chemical processes on the formation of secondary aerosols in the region, with special focus on nocturnal ammonium nitrate formation and its implications (aqueous formation of secondary organic aerosol).
Amy P. Sullivan, Natasha Hodas, Barbara J. Turpin, Kate Skog, Frank N. Keutsch, Stefania Gilardoni, Marco Paglione, Matteo Rinaldi, Stefano Decesari, Maria Cristina Facchini, Laurent Poulain, Hartmut Herrmann, Alfred Wiedensohler, Eiko Nemitz, Marsailidh M. Twigg, and Jeffrey L. Collett Jr.
Atmos. Chem. Phys., 16, 8095–8108,Short summary
This paper presents the results from our measurements and approach for the investigation of aqueous secondary organic aerosol (aqSOA) formation in the ambient atmosphere. When local aqSOA formation was observed, a correlation of water-soluble organic carbon with organic aerosol, aerosol liquid water, relative humidity, and aerosol nitrate was found. Key factors of local aqSOA production include air mass stagnation, formation of local nitrate overnight, and significant amounts of ammonia.
Carlo De Michele, Francesco Avanzi, Daniele Passoni, Riccardo Barzaghi, Livio Pinto, Paolo Dosso, Antonio Ghezzi, Roberto Gianatti, and Giacomo Della Vedova
The Cryosphere, 10, 511–522,Short summary
We investigate snow depth distribution at peak accumulation over a small Alpine area using photogrammetry-based surveys with a fixed wing unmanned aerial system. Results reveal that UAS estimations of point snow depth present an average difference with reference to manual measurements equal to -0.073 m. Moreover, in this case study snow depth standard deviation (hence coefficient of variation) increases with decreasing cell size, but it stabilizes for resolutions smaller than 1 m.
M. Rinaldi, S. Gilardoni, M. Paglione, S. Sandrini, S. Fuzzi, P. Massoli, P. Bonasoni, P. Cristofanelli, A. Marinoni, V. Poluzzi, and S. Decesari
Atmos. Chem. Phys., 15, 11327–11340,Short summary
This work highlights the important contribution of organic aerosols to the composition of submicron particles at remote mountain sites. Moreover, it confirms the importance of regional-scale physical and chemical processes and of transboundary transport in determining the background aerosol composition at rural European sites.
S. Fuzzi, U. Baltensperger, K. Carslaw, S. Decesari, H. Denier van der Gon, M. C. Facchini, D. Fowler, I. Koren, B. Langford, U. Lohmann, E. Nemitz, S. Pandis, I. Riipinen, Y. Rudich, M. Schaap, J. G. Slowik, D. V. Spracklen, E. Vignati, M. Wild, M. Williams, and S. Gilardoni
Atmos. Chem. Phys., 15, 8217–8299,Short summary
Particulate matter (PM) constitutes one of the most challenging problems both for air quality and climate change policies. This paper reviews the most recent scientific results on the issue and the policy needs that have driven much of the increase in monitoring and mechanistic research over the last 2 decades. The synthesis reveals many new processes and developments in the science underpinning climate-PM interactions and the effects of PM on human health and the environment.
P. Licznar, C. De Michele, and W. Adamowski
Hydrol. Earth Syst. Sci., 19, 485–506,
P. Da Ronco and C. De Michele
Hydrol. Earth Syst. Sci., 18, 4579–4600,Short summary
The negative impacts of cloud obstruction in snow mapping from MODIS and a new reliable cloud removal procedure for the Italian Alps.
S. Gilardoni, P. Massoli, L. Giulianelli, M. Rinaldi, M. Paglione, F. Pollini, C. Lanconelli, V. Poluzzi, S. Carbone, R. Hillamo, L. M. Russell, M. C. Facchini, and S. Fuzzi
Atmos. Chem. Phys., 14, 6967–6981,
K. Saarnio, K. Teinilä, S. Saarikoski, S. Carbone, S. Gilardoni, H. Timonen, M. Aurela, and R. Hillamo
Atmos. Meas. Tech., 6, 2839–2849,
Related subject area
Subject: Aerosols | Research Activity: Atmospheric Modelling | Altitude Range: Troposphere | Science Focus: Physics (physical properties and processes)Causal influences of El Niño–Southern Oscillation on global dust activitiesFormation, radiative forcing, and climatic effects of severe regional hazeAdvances in air quality research – current and emerging challengesLarge-eddy-simulation study on turbulent particle deposition and its dependence on atmospheric-boundary-layer stabilityAerosol indirect effects in complex-orography areas: a numerical study over the Great Alpine RegionModelling the size distribution of aggregated volcanic ash and implications for operational atmospheric dispersion modellingThe effect of BC on aerosol–boundary layer feedback: potential implications for urban pollution episodesRelative importance of high-latitude local and long-range-transported dust for Arctic ice-nucleating particles and impacts on Arctic mixed-phase cloudsTechnical note: Dispersion of cooking-generated aerosols from an urban street canyonComparison of six approaches to predicting droplet activation of surface active aerosol – Part 1: moderately surface active organicsThe contribution of coral-reef-derived dimethyl sulfide to aerosol burden over the Great Barrier Reef: a modelling studyDevelopment and application of a street-level meteorology and pollutant tracking system (S-TRACK)How well do the CMIP6 models simulate dust aerosols?Input-adaptive linear mixed-effects model for estimating alveolar lung-deposited surface area (LDSA) using multipollutant datasetsSimulated impacts of vertical distributions of black carbon aerosol on meteorology and PM2.5 concentrations in Beijing during severe haze eventsData assimilation of volcanic aerosol observations using FALL3D+PDAFSimulation of the effects of low-volatility organic compounds on aerosol number concentrations in EuropeNew particle formation event detection with Mask R-CNNContribution of traffic-originated nanoparticle emissions to regional and local aerosol levelsReassessment of the radiocesium resuspension flux from contaminated ground surfaces in eastern JapanDuff burning from wildfires in a moist region: different impacts on PM2.5 and ozoneAssimilating spaceborne lidar dust extinction can improve dust forecastsAssessing the value meteorological ensembles add to dispersion modelling using hypothetical releasesEffects of oligomerization and decomposition on the nanoparticle growth: a model studyThe role of anthropogenic aerosols in the anomalous cooling from 1960 to 1990 in the CMIP6 Earth system modelsConstant flux layers with gravitational settling: links to aerosols, fog and deposition velocitiesCombining POLDER-3 satellite observations and WRF-Chem numerical simulations to derive biomass burning aerosol properties over the southeast Atlantic regionIs the Atlantic Ocean driving the recent variability in South Asian dust?Molecular-scale description of interfacial mass transfer in phase-separated aqueous secondary organic aerosolExploring the uncertainties in the aviation soot–cirrus effectReduced effective radiative forcing from cloud–aerosol interactions (ERFaci) with improved treatment of early aerosol growth in an Earth system modelHyperfine-resolution mapping of on-road vehicle emissions with comprehensive traffic monitoring and an intelligent transportation systemLess atmospheric radiative heating by dust due to the synergy of coarser size and aspherical shapeAir quality deterioration episode associated with a typhoon over the complex topographic environment in central TaiwanImpact of modified turbulent diffusion of PM2.5 aerosol in WRF-Chem simulations in eastern ChinaWhat rainfall rates are most important to wet removal of different aerosol types?A weather regime characterisation of winter biomass aerosol transport from southern Africa15-year variability of desert dust optical depth on global and regional scalesDipole pattern of summer ozone pollution in the east of China and its connection with climate variabilityAerosol absorption in global models from AeroCom phase IIIA black carbon peak and its sources in the free troposphere of Beijing induced by cyclone lifting and transport from central ChinaCompeting effects of aerosol reductions and circulation changes for future improvements in Beijing hazeUnderstanding the surface temperature response and its uncertainty to CO2, CH4, black carbon, and sulfateSurface deposition of marine fog and its treatment in the Weather Research and Forecasting (WRF) modelAssessing the potential efficacy of marine cloud brightening for cooling Earth using a simple heuristic modelAerosol effects on electrification and lightning discharges in a multicell thunderstorm simulated by the WRF-ELEC modelThe response of the Amazon ecosystem to the photosynthetically active radiation fields: integrating impacts of biomass burning aerosol and clouds in the NASA GEOS Earth system model“Warm cover”: precursory strong signals for haze pollution hidden in the middle troposphereThe MAPM (Mapping Air Pollution eMissions) method for inferring particulate matter emissions maps at city scale from in situ concentration measurements: description and demonstration of capabilityCharacteristics of surface energy balance and atmospheric circulation during hot-and-polluted episodes and their synergistic relationships with urban heat islands over the Pearl River Delta region
Thanh Le and Deg-Hyo Bae
Atmos. Chem. Phys., 22, 5253–5263,Short summary
Here we assess the response of dust activities to El Niño–Southern Oscillation (ENSO) over the 1850–2014 period using climate model outputs. Our results show that ENSO is an important driver of dust deposition and dust transportation with high consensus across models. However, the results indicate that ENSO is unlikely to show causal impacts on dust emissions of major dust sources. This study allows us to obtain further understanding of the linkages between ENSO and dust cycle at a global scale.
Yun Lin, Yuan Wang, Bowen Pan, Jiaxi Hu, Song Guo, Misti Levy Zamora, Pengfei Tian, Qiong Su, Yuemeng Ji, Jiayun Zhao, Mario Gomez-Hernandez, Min Hu, and Renyi Zhang
Atmos. Chem. Phys., 22, 4951–4967,Short summary
Severe regional haze events, which are characterized by exceedingly high levels of fine particulate matter (PM), occur frequently in many developing countries (such as China and India), with profound implications for human health, weather, and climate. Our work establishes a synthetic view for the dominant regional features during severe haze events, unraveling rapid in situ PM production and inefficient transport, both of which are amplified by atmospheric stagnation.
Ranjeet S. Sokhi, Nicolas Moussiopoulos, Alexander Baklanov, John Bartzis, Isabelle Coll, Sandro Finardi, Rainer Friedrich, Camilla Geels, Tiia Grönholm, Tomas Halenka, Matthias Ketzel, Androniki Maragkidou, Volker Matthias, Jana Moldanova, Leonidas Ntziachristos, Klaus Schäfer, Peter Suppan, George Tsegas, Greg Carmichael, Vicente Franco, Steve Hanna, Jukka-Pekka Jalkanen, Guus J. M. Velders, and Jaakko Kukkonen
Atmos. Chem. Phys., 22, 4615–4703,Short summary
This review of air quality research focuses on developments over the past decade. The article considers current and future challenges that are important from air quality research and policy perspectives and highlights emerging prominent gaps of knowledge. The review also examines how air pollution management needs to adapt to new challenges and makes recommendations to guide the direction for future air quality research within the wider community and to provide support for policy.
Xin Yin, Cong Jiang, Yaping Shao, Ning Huang, and Jie Zhang
Atmos. Chem. Phys., 22, 4509–4522,Short summary
Through a series of numerical experiments using the large-eddy-simulation model, we have developed an improved particle deposition scheme that takes into account transient wind shear fluctuations. Statistical analysis of the simulation results shows that the shear stress can be well approximated by a Weibull distribution and that the new scheme provides more accurate predictions than the conventional scheme, particularly under weak wind conditions and strong convective atmospheric conditions.
Anna Napoli, Fabien Desbiolles, Antonio Parodi, and Claudia Pasquero
Atmos. Chem. Phys., 22, 3901–3909,Short summary
Aerosols are liquid or solid particles suspended in the air that can interact with radiation and clouds, modifying the meteoclimatic conditions. Using an atmospheric model, we study the climatological impact of aerosols through their effects on clouds in the Alps, a region characterized by high pollution levels in the densely populated surrounding flatlands. Results show that cloud cover, temperature, and precipitation are affected by aerosols, and the response varies with elevation and season.
Frances Beckett, Eduardo Rossi, Benjamin Devenish, Claire Witham, and Costanza Bonadonna
Atmos. Chem. Phys., 22, 3409–3431,Short summary
As volcanic ash is transported through the atmosphere, it may collide and stick together to form aggregates. Neglecting the process of aggregation in atmospheric dispersion models could lead to inaccurate forecasts used by civil aviation for hazard assessment. We developed an aggregation scheme for use with the model NAME, which is used by the London Volcanic Ash Advisory Centre. Using our scheme, we investigate the impact of aggregation on simulations of the 2010 Eyjafjallajökull ash cloud.
Jessica Slater, Hugh Coe, Gordon McFiggans, Juha Tonttila, and Sami Romakkaniemi
Atmos. Chem. Phys., 22, 2937–2953,Short summary
This paper shows the specific impact of black carbon (BC) on the aerosol–planetary boundary layer (PBL) feedback and its influence on a Beijing haze episode. Overall, this paper shows that strong temperature inversions prevent BC heating within the PBL from significantly increasing PBL height, while BC above the PBL suppresses PBL development significantly through the day. From this we suggest a method by which both locally and regionally emitted BC may impact urban pollution episodes.
Yang Shi, Xiaohong Liu, Mingxuan Wu, Xi Zhao, Ziming Ke, and Hunter Brown
Atmos. Chem. Phys., 22, 2909–2935,Short summary
We perform a modeling study to evaluate the contribution to Arctic dust loading and ice-nucleating particle (INP) population from high-latitude local and low-latitude dust. High-latitude dust has a large contribution in the lower troposphere, while low-latitude dust dominates the upper troposphere. The high-latitude dust INPs result in a net cooling effect on the Arctic surface by glaciating mixed-phase clouds. Our results highlight the contribution of high-latitude dust to the Arctic climate.
Shang Gao, Mona Kurppa, Chak K. Chan, and Keith Ngan
Atmos. Chem. Phys., 22, 2703–2726,Short summary
The contribution of cooking emissions to organic aerosols may exceed that of motor vehicles. However, little is known about how cooking-generated aerosols evolve in the outdoor environment. In this paper, we present a numerical study of the dispersion of cooking emissions. For plausible choices of the emission strength, cooking can yield much higher concentrations than traffic. This has important implications for public health and city planning.
Sampo Vepsäläinen, Silvia M. Calderón, Jussi Malila, and Nønne L. Prisle
Atmos. Chem. Phys., 22, 2669–2687,Short summary
Atmospheric aerosols act as seeds for cloud formation. Many aerosols contain surface active material that accumulates at the surface of growing droplets. This can affect cloud droplet activation, but the broad significance of the effect and the best way to model it are still debated. We compare predictions of six different model approaches to surface activity of organic aerosols and find significant differences between the models, especially with large fractions of organics in the dry particles.
Sonya L. Fiddes, Matthew T. Woodhouse, Steve Utembe, Robyn Schofield, Simon P. Alexander, Joel Alroe, Scott D. Chambers, Zhenyi Chen, Luke Cravigan, Erin Dunne, Ruhi S. Humphries, Graham Johnson, Melita D. Keywood, Todd P. Lane, Branka Miljevic, Yuko Omori, Alain Protat, Zoran Ristovski, Paul Selleck, Hilton B. Swan, Hiroshi Tanimoto, Jason P. Ward, and Alastair G. Williams
Atmos. Chem. Phys., 22, 2419–2445,Short summary
Coral reefs have been found to produce the climatically relevant chemical compound dimethyl sulfide (DMS). It has been suggested that corals can modify their environment via the production of DMS. We use an atmospheric chemistry model to test this theory at a regional scale for the first time. We find that it is unlikely that coral-reef-derived DMS has an influence over local climate, in part due to the proximity to terrestrial and anthropogenic aerosol sources.
Huan Zhang, Sunling Gong, Lei Zhang, Jingwei Ni, Jianjun He, Yaqiang Wang, Xu Wang, Lixin Shi, Jingyue Mo, Huabing Ke, and Shuhua Lu
Atmos. Chem. Phys., 22, 2221–2236,Short summary
This study established a multi-model simulation system for street-level circulation and pollutant tracking and applied to real building scenarios and atmospheric conditions. Results showed that for a particular site the potential contribution ratio varies with the height of the site, with a peak not at the ground but at a certain height. This work is of significance for urban planning and improvement of urban air quality.
Alcide Zhao, Claire L. Ryder, and Laura J. Wilcox
Atmos. Chem. Phys., 22, 2095–2119,Short summary
The CMIP6 models' simulated dust processes are getting more uncertain as models become more sophisticated. Of particular challenge are the links between dust cycles and optical properties, and we recommend more detailed output relating to dust cycles in future intercomparison projects to constrain such links. Also, models struggle to capture certain key regional dust processes such as dust accumulation along the slope of the Himalayas and dust seasonal cycles in North China and North America.
Pak Lun Fung, Martha A. Zaidan, Jarkko V. Niemi, Erkka Saukko, Hilkka Timonen, Anu Kousa, Joel Kuula, Topi Rönkkö, Ari Karppinen, Sasu Tarkoma, Markku Kulmala, Tuukka Petäjä, and Tareq Hussein
Atmos. Chem. Phys., 22, 1861–1882,Short summary
We developed an input-adaptive mixed-effects model, which was automatised to select the best combination of input variables, including up to three fixed effect variables and three time indictors as random effect variables. We tested the model to estimate lung-deposited surface area (LDSA), which correlates well with human health. The results show the inclusion of time indicators improved the sensitivity and the accuracy of the model so that it could serve as a network of virtual sensors.
Donglin Chen, Hong Liao, Yang Yang, Lei Chen, Delong Zhao, and Deping Ding
Atmos. Chem. Phys., 22, 1825–1844,Short summary
The black carbon (BC) vertical profile plays a critical role in BC–meteorology interaction, which also influences PM2.5 concentrations. More BC mass was assigned into high altitudes (above 1000 m) in the model, which resulted in a stronger cooling effect near the surface, a larger temperature inversion below 421 m, more reductions in PBLH, and a larger increase in near-surface PM2.5 in the daytime caused by the direct radiative effect of BC.
Leonardo Mingari, Arnau Folch, Andrew T. Prata, Federica Pardini, Giovanni Macedonio, and Antonio Costa
Atmos. Chem. Phys., 22, 1773–1792,Short summary
We present a new implementation of an ensemble-based data assimilation method to improve forecasting of volcanic aerosols. This system can be efficiently integrated into operational workflows by exploiting high-performance computing resources. We found a dramatic improvement of forecast quality when satellite retrievals are continuously assimilated. Management of volcanic risk and reduction of aviation impacts can strongly benefit from this research.
David Patoulias and Spyros N. Pandis
Atmos. Chem. Phys., 22, 1689–1706,Short summary
Our simulations indicate that the recently identified production and subsequent condensation effect of extremely low-volatility organic compounds have a smaller-than-expected effect on the total concentration of atmospheric particles. On the other hand, the oxidation of intermediate-volatility organic compounds leads to decreases in the ultrafine-particle concentrations. These results improve our understanding of the links between secondary organic aerosol formation and ultrafine particles.
Peifeng Su, Jorma Joutsensaari, Lubna Dada, Martha Arbayani Zaidan, Tuomo Nieminen, Xinyang Li, Yusheng Wu, Stefano Decesari, Sasu Tarkoma, Tuukka Petäjä, Markku Kulmala, and Petri Pellikka
Atmos. Chem. Phys., 22, 1293–1309,Short summary
We regarded the banana shapes in the surface plots as a special kind of object (similar to cats) and applied an instance segmentation technique to automatically identify the new particle formation (NPF) events (especially the strongest ones), in addition to their growth rates, start times, and end times. The automatic method generalized well on datasets collected in different sites, which is useful for long-term data series analysis and obtaining statistical properties of NPF events.
Miska Olin, David Patoulias, Heino Kuuluvainen, Jarkko V. Niemi, Topi Rönkkö, Spyros N. Pandis, Ilona Riipinen, and Miikka Dal Maso
Atmos. Chem. Phys., 22, 1131–1148,Short summary
An emission factor particle size distribution was determined from the measurements at an urban traffic site. It was used in updating a pre-existing emission inventory, and regional modeling was performed after the update. Emission inventories typically underestimate nanoparticle emissions due to challenges in determining them with high certainty. This update reveals that the simulated aerosol levels have previously been underestimated especially for urban areas and for sub-50 nm particles.
Mizuo Kajino, Akira Watanabe, Masahide Ishizuka, Kazuyuki Kita, Yuji Zaizen, Takeshi Kinase, Rikuya Hirai, Kakeru Konnai, Akane Saya, Kazuki Iwaoka, Yoshitaka Shiroma, Hidenao Hasegawa, Naofumi Akata, Masahiro Hosoda, Shinji Tokonami, and Yasuhito Igarashi
Atmos. Chem. Phys., 22, 783–803,Short summary
Using a numerical model and observations of surface concentration and depositions, the current study provides quantitative assessments of resuspension, transport, and deposition of radio-Cs in eastern Japan in 2013, which was once deposited to the ground surface after the Fukushima nuclear accident. The areal mean resuspension rate of radio-Cs from the ground to the air is estimated as 0.96 % per year, which is equivalent to 1–10 % of the decreasing rate of the ambient gamma dose in Fukushima.
Aoxing Zhang, Yongqiang Liu, Scott Goodrick, and Marcus D. Williams
Atmos. Chem. Phys., 22, 597–624,Short summary
Duff is decomposed forest fuel under ground. Duff burning often occurs at the smoldering phase with low intensity and long periods, which has little impact on regional air quality. However, there is increasing evidence for duff burning during flaming phases. This study simulates the air quality impacts of duff burning during flaming phases in the southeastern US using a regional air quality model. The results indicate the important contributions of such burning to regional PM2.5 concentrations.
Jerónimo Escribano, Enza Di Tomaso, Oriol Jorba, Martina Klose, Maria Gonçalves Ageitos, Francesca Macchia, Vassilis Amiridis, Holger Baars, Eleni Marinou, Emmanouil Proestakis, Claudia Urbanneck, Dietrich Althausen, Johannes Bühl, Rodanthi-Elisavet Mamouri, and Carlos Pérez García-Pando
Atmos. Chem. Phys., 22, 535–560,Short summary
We explore the benefits and consistency in adding lidar dust observations in a dust optical depth assimilation. We show that adding lidar data to a dust optical depth assimilation has valuable benefits and the dust analysis improves. We discuss the impact of the narrow satellite footprint of the lidar dust observations on the assimilation.
Susan J. Leadbetter, Andrew R. Jones, and Matthew C. Hort
Atmos. Chem. Phys., 22, 577–596,Short summary
In this study we look at the ability of meteorological ensembles (multiple realisations of the meteorological data) to provide information about the uncertainty in the dispersion model predictions. Statistical measures are used to evaluate the model predictions, and these show that on average the ensemble predictions outperform the non-ensemble predictions.
Arto Heitto, Kari Lehtinen, Tuukka Petäjä, Felipe Lopez-Hilfiker, Joel A. Thornton, Markku Kulmala, and Taina Yli-Juuti
Atmos. Chem. Phys., 22, 155–171,Short summary
For atmospheric aerosol particles to take part in cloud formation, they need to be at least a few tens of nanometers in diameter. By using a particle condensation model, we investigated how two types of chemical reactions, oligomerization and decomposition, of organic molecules inside the particle may affect the growth of secondary aerosol particles to these sizes. We show that the effect is potentially significant, which highlights the importance of increasing understanding of these processes.
Jie Zhang, Kalli Furtado, Steven T. Turnock, Jane P. Mulcahy, Laura J. Wilcox, Ben B. Booth, David Sexton, Tongwen Wu, Fang Zhang, and Qianxia Liu
Atmos. Chem. Phys., 21, 18609–18627,Short summary
The CMIP6 ESMs systematically underestimate TAS anomalies in the NH midlatitudes, especially from 1960 to 1990. The anomalous cooling is concurrent in time and space with anthropogenic SO2 emissions. The spurious drop in TAS is attributed to the overestimated aerosol concentrations. The aerosol forcing sensitivity cannot well explain the inter-model spread of PHC biases. And the cloud-amount term accounts for most of the inter-model spread in aerosol forcing sensitivity.
Peter A. Taylor
Atmos. Chem. Phys., 21, 18263–18269,Short summary
Atmospheric aerosols including fog droplets can be deposited on the ground or on water surfaces. This is due to both gravitational settling and turbulent impaction. A simple model of this combined process is developed based on conventional atmospheric-boundary-layer ideas. The model suggests an alternative formulation for the treatment of gravitational settling in the deposition velocity estimations of aerosol particles and fog droplets.
Alexandre Siméon, Fabien Waquet, Jean-Christophe Péré, Fabrice Ducos, François Thieuleux, Fanny Peers, Solène Turquety, and Isabelle Chiapello
Atmos. Chem. Phys., 21, 17775–17805,Short summary
For the first time, we accurately modelled the optical properties of the biomass burning aerosols (BBA) observed over the Southeast Atlantic region during their transport above clouds and over their source regions, combining a meteorology coupled with chemistry model (WRF-Chem) with innovative satellite absorbing aerosol retrievals (POLDER-3). Our results suggest a low but non-negligible brown carbon fraction (3 %) for the chemical composition of the BBA plumes observed over the source regions.
Priyanka Banerjee, Sreedharan Krishnakumari Satheesh, and Krishnaswamy Krishna Moorthy
Atmos. Chem. Phys., 21, 17665–17685,Short summary
We show that the Atlantic Ocean is the major driver of interannual variability in dust over South Asia since the second decade of the 21st century. This is a shift from the previously important role played by the Pacific Ocean in controlling dust over this region. Following the end of the recent global warming hiatus, anomalies of the North Atlantic sea surface temperature have remotely invoked a weakening of the South Asian monsoon and a strengthening of the dust-bearing northwesterlies.
Mária Lbadaoui-Darvas, Satoshi Takahama, and Athanasios Nenes
Atmos. Chem. Phys., 21, 17687–17714,Short summary
Aerosol–cloud interactions constitute the most uncertain contribution to climate change. The uptake kinetics of water by aerosol is a central process of cloud droplet formation, yet its molecular-scale mechanism is unknown. We use molecular simulations to study this process for phase-separated organic particles. Our results explain the increased cloud condensation activity of such particles and can be generalized over various compositions, thus possibly serving as a basis for future models.
Mattia Righi, Johannes Hendricks, and Christof Gerhard Beer
Atmos. Chem. Phys., 21, 17267–17289,Short summary
A global climate model is applied to simulate the impact of aviation soot on natural cirrus clouds. A large number of numerical experiments are performed to analyse how the quantification of the resulting climate impact is affected by known uncertainties. These concern the ability of aviation soot to nucleate ice and the role of model dynamics. Our results show that both aspects are important for the quantification of this effect and that discrepancies among different model studies still exist.
Sara Marie Blichner, Moa Kristina Sporre, and Terje Koren Berntsen
Atmos. Chem. Phys., 21, 17243–17265,Short summary
In this study we quantify how a new way of modeling the formation of new particles in the atmosphere affects the estimated cooling from aerosol–cloud interactions since pre-industrial times. Our improved scheme merges two common approaches to aerosol modeling: a sectional scheme for treating early growth and the pre-existing modal scheme in NorESM. We find that the cooling from aerosol–cloud interactions since pre-industrial times is reduced by 10 % when the new scheme is used.
Linhui Jiang, Yan Xia, Lu Wang, Xue Chen, Jianjie Ye, Tangyan Hou, Liqiang Wang, Yibo Zhang, Mengying Li, Zhen Li, Zhe Song, Yaping Jiang, Weiping Liu, Pengfei Li, Daniel Rosenfeld, John H. Seinfeld, and Shaocai Yu
Atmos. Chem. Phys., 21, 16985–17002,Short summary
This paper establishes a bottom-up approach to reveal a unique pattern of urban on-road vehicle emissions at a spatial resolution 1–3 orders of magnitude higher than current inventories. The results show that the hourly average on-road vehicle emissions of CO, NOx, HC, and PM2.5 are 74 kg, 40 kg, 8 kg, and 2 kg, respectively. Integrating our traffic-monitoring-based approach with urban measurements, we could address major data gaps between urban air pollutant emissions and concentrations.
Akinori Ito, Adeyemi A. Adebiyi, Yue Huang, and Jasper F. Kok
Atmos. Chem. Phys., 21, 16869–16891,Short summary
We improve the simulated dust properties of size-resolved dust concentration and particle shape. The improved simulation suggests much less atmospheric radiative heating near the major source regions, because of enhanced longwave warming at the surface by the synergy of coarser size and aspherical shape. Less intensified atmospheric heating could substantially modify the vertical temperature profile in Earth system models and thus has important implications for the projection of dust feedback.
Chuan-Yao Lin, Yang-Fan Sheng, Wan-Chin Chen, Charles C. K. Chou, Yi-Yun Chien, and Wen-Mei Chen
Atmos. Chem. Phys., 21, 16893–16910,Short summary
Taiwan and Hong Kong experience air quality deterioration as typhoons approach. However, the mechanism of the formation of poor air quality may differ and still not be well documented in Taiwan. The interaction between easterly typhoon circulation and Taiwan’s Central Mountain Range resulted in a lee side vortex formation. Simulation results indicated that the lee vortex and land–sea breeze, as well as the boundary layer development, were the key mechanisms.
Wenxing Jia and Xiaoye Zhang
Atmos. Chem. Phys., 21, 16827–16841,Short summary
Heavy aerosol pollution incidents have attracted much attention since 2013, but the temporal and spatial limitations of observations and the inaccuracy of simulation are a stumbling block to assessing pollution mechanisms. The correct simulation of boundary layer mixing process of pollutant is a challenge for mesoscale numerical models. We add the turbulent diffusion term of aerosol to the WRF-Chem model to prove the impact of turbulent diffusion on pollutant concentration.
Yong Wang, Wenwen Xia, and Guang J. Zhang
Atmos. Chem. Phys., 21, 16797–16816,Short summary
This study developed a novel approach to detect what rainfall rates climatologically are most efficient for wet removal of different aerosol types and applied it to a global climate model (GCM). Results show that light rain has disproportionate control on aerosol wet scavenging, with distinct rain rates for different aerosol sizes. The approach can be applied to other GCMs to better understand the aerosol wet scavenging by rainfall, which is important to better simulate aerosols.
Marco Gaetani, Benjamin Pohl, Maria del Carmen Alvarez Castro, Cyrille Flamant, and Paola Formenti
Atmos. Chem. Phys., 21, 16575–16591,Short summary
During the dry austral winter, biomass fires in tropical Africa emit large amounts of smoke in the atmosphere, with large impacts on climate and air quality. The study of the relationship between atmospheric circulation and smoke transport shows that midlatitude atmospheric disturbances may deflect the smoke from tropical Africa towards southern Africa. Understanding the distribution of the smoke in the region is crucial for climate modelling and air quality monitoring.
Stavros-Andreas Logothetis, Vasileios Salamalikis, Antonis Gkikas, Stelios Kazadzis, Vassilis Amiridis, and Andreas Kazantzidis
Atmos. Chem. Phys., 21, 16499–16529,Short summary
This study investigates the temporal trends of dust optical depth (DOD; 550 nm) on global, regional and seasonal scales over a 15-year period (2003–2017) using the MIDAS (ModIs Dust AeroSol) dataset. The findings of this study revealed that the DOD was increased across the central Sahara and the Arabian Peninsula, with opposite trends over the eastern and western Sahara, the Thar and Gobi deserts, in the Bodélé Depression, and in the southern Mediterranean.
Xiaoqing Ma and Zhicong Yin
Atmos. Chem. Phys., 21, 16349–16361,Short summary
Severe ozone pollution frequently occurred in the east of China and obviously damages human health. The meteorological conditions effectively affect the variations in ozone pollution by modulating the natural emissions of ozone precursors and photochemical reactions in the atmosphere. In this study, a south–north dipole pattern of summer-mean ozone concentration in the east of China was identified, and its connections with preceding climate variability at different latitudes were also examined.
Maria Sand, Bjørn H. Samset, Gunnar Myhre, Jonas Gliß, Susanne E. Bauer, Huisheng Bian, Mian Chin, Ramiro Checa-Garcia, Paul Ginoux, Zak Kipling, Alf Kirkevåg, Harri Kokkola, Philippe Le Sager, Marianne T. Lund, Hitoshi Matsui, Twan van Noije, Dirk J. L. Olivié, Samuel Remy, Michael Schulz, Philip Stier, Camilla W. Stjern, Toshihiko Takemura, Kostas Tsigaridis, Svetlana G. Tsyro, and Duncan Watson-Parris
Atmos. Chem. Phys., 21, 15929–15947,Short summary
Absorption of shortwave radiation by aerosols can modify precipitation and clouds but is poorly constrained in models. A total of 15 different aerosol models from AeroCom phase III have reported total aerosol absorption, and for the first time, 11 of these models have reported in a consistent experiment the contributions to absorption from black carbon, dust, and organic aerosol. Here, we document the model diversity in aerosol absorption.
Zhenbin Wang, Bin Zhu, Hanqing Kang, Wen Lu, Shuqi Yan, Delong Zhao, Weihang Zhang, and Jinhui Gao
Atmos. Chem. Phys., 21, 15555–15567,Short summary
In this paper, by using WRF-Chem with a black carbon (BC) tagging technique, we investigate the formation mechanism and regional sources of a BC peak in the free troposphere observed by aircraft flights. Local sources dominated BC from the surface to about 700 m (78.5 %), while the BC peak in the free troposphere was almost entirely imported from external sources (99.8 %). Our results indicate that cyclone systems can quickly lift BC up to the free troposphere, as well as extend its lifetime.
Liang Guo, Laura J. Wilcox, Massimo Bollasina, Steven T. Turnock, Marianne T. Lund, and Lixia Zhang
Atmos. Chem. Phys., 21, 15299–15308,Short summary
Severe haze remains serious over Beijing despite emissions decreasing since 2008. Future haze changes in four scenarios are studied. The pattern conducive to haze weather increases with the atmospheric warming caused by the accumulation of greenhouse gases. However, the actual haze intensity, measured by either PM2.5 or optical depth, decreases with aerosol emissions. We show that only using the weather pattern index to predict the future change of Beijing haze is insufficient.
Kalle Nordling, Hannele Korhonen, Jouni Räisänen, Antti-Ilari Partanen, Bjørn H. Samset, and Joonas Merikanto
Atmos. Chem. Phys., 21, 14941–14958,Short summary
Understanding the temperature responses to different climate forcing agents, such as greenhouse gases and aerosols, is crucial for understanding future regional climate changes. In climate models, the regional temperature responses vary for all forcing agents, but the causes of this variability are poorly understood. For all forcing agents, the main component contributing to variance in regional surface temperature responses between the climate models is the clear-sky longwave emissivity.
Peter A. Taylor, Zheqi Chen, Li Cheng, Soudeh Afsharian, Wensong Weng, George A. Isaac, Terry W. Bullock, and Yongsheng Chen
Atmos. Chem. Phys., 21, 14687–14702,Short summary
In marine fog, droplets will impact the water surface, collide and coalesce. This removal process is underestimated or ignored in many fog and weather forecast models. A new atmospheric boundary layer approach is proposed and tested in a standard weather forecast model (Weather Research and Forecasting, WRF). New profile measurements through marine fog layers are suggested.
Atmos. Chem. Phys., 21, 14507–14533,Short summary
A simple model is described to assess the potential for increasing solar reflection by augmenting the aerosol population below marine low clouds, which increases the concentration of cloud droplets. The model is used to predict global cooling from marine cloud brightening climate intervention as a function of the quantity, size, and lifetime of salt particles injected per sprayer, the number of sprayers deployed, the cloud updraft speed, and unperturbed aerosol size distribution.
Mengyu Sun, Dongxia Liu, Xiushu Qie, Edward R. Mansell, Yoav Yair, Alexandre O. Fierro, Shanfeng Yuan, Zhixiong Chen, and Dongfang Wang
Atmos. Chem. Phys., 21, 14141–14158,Short summary
By acting as cloud condensation nuclei (CCN), increasing aerosol loading tends to enhance lightning activity through microphysical processes. We investigated the aerosol effects on the development of a thunderstorm. A two-moment bulk microphysics scheme and bulk lightning model were coupled in the WRF Model to simulate a multicell thunderstorm. Sensitivity experiments show that the enhancement of lightning activity under polluted conditions results from an increasing ice crystal number.
Huisheng Bian, Eunjee Lee, Randal D. Koster, Donifan Barahona, Mian Chin, Peter R. Colarco, Anton Darmenov, Sarith Mahanama, Michael Manyin, Peter Norris, John Shilling, Hongbin Yu, and Fanwei Zeng
Atmos. Chem. Phys., 21, 14177–14197,Short summary
The study using the NASA Earth system model shows ~2.6 % increase in burning season gross primary production and ~1.5 % increase in annual net primary production across the Amazon Basin during 2010–2016 due to the change in surface downward direct and diffuse photosynthetically active radiation by biomass burning aerosols. Such an aerosol effect is strongly dependent on the presence of clouds. The cloud fraction at which aerosols switch from stimulating to inhibiting plant growth occurs at ~0.8.
Xiangde Xu, Wenyue Cai, Tianliang Zhao, Xinfa Qiu, Wenhui Zhu, Chan Sun, Peng Yan, Chunzhu Wang, and Fei Ge
Atmos. Chem. Phys., 21, 14131–14139,Short summary
We found that the structure of atmospheric thermodynamics in the troposphere can be regarded as a strong forewarning signal for variations of surface PM2.5 concentration in heavy air pollution.
Brian Nathan, Stefanie Kremser, Sara Mikaloff-Fletcher, Greg Bodeker, Leroy Bird, Ethan Dale, Dongqi Lin, Gustavo Olivares, and Elizabeth Somervell
Atmos. Chem. Phys., 21, 14089–14108,Short summary
The MAPM project showcases a method to improve estimates of PM2.5 emissions through an advanced statistical technique that is still new to the aerosol community. Using Christchurch, NZ, as a test bed, measurements from a field campaign in winter 2019 are incorporated into this new approach. An overestimation from local inventory estimates is identified. This technique may be exported to other urban areas in need.
Ifeanyichukwu C. Nduka, Chi-Yung Tam, Jianping Guo, and Steve Hung Lam Yim
Atmos. Chem. Phys., 21, 13443–13454,Short summary
This study analyzed the nature, mechanisms and drivers for hot-and-polluted episodes (HPEs) in the Pearl River Delta, China. A total of eight HPEs were identified and can be grouped into three clusters of HPEs that were respectively driven (1) by weak subsidence and convection induced by approaching tropical cyclones, (2) by calm conditions with low wind speed in the lower atmosphere and (3) by the combination of both aforementioned conditions.
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The aerosol particle number size distributions (PNSDs) measured in one urban background site (Milan) and in one rural mountainous site (Oga San Colombano) have been studied and compared. Detailed statistical analyses have shown that a common empirical PNSD pattern exists, except for the urban winter data. In order to explain this phenomenon, we analysed the aerosol dynamics by considering the influence of primary aerosol components and the interaction with precipitation and high wind speed.
The aerosol particle number size distributions (PNSDs) measured in one urban background site...