Experimental investigation of ion–ion recombination under atmospheric conditions
Summary: The ion-ion recombination coefficient was measured at different temperatures, relative humidities and concentrations of ozone and sulfur dioxide. The experiments were carried out using the CLOUD chamber at CERN. We observed a strong dependency on temperature and on relative humidity, which has not been reported previously. No dependency of the ion-ion recombination coefficient on ozone concentration was observed and a weak variation with sulfur dioxide concentration was also observed.
Atmos. Chem. Phys., 15, 7203-7216, doi:10.5194/acp-15-7203-2015, 2015
A simple formulation of the CH2O photolysis quantum yields
Summary: We present a new way to formulate the quantum yields of formaldehyde with several advantages. The formulation is simpler and has fewer parameters than those used so far, and the parameters have a physical meaning. It provides a template for the formulation of other quantum yields, e.g., of the isotopologues of formaldehyde. In addition, we offer a careful review of published measurements. It is also advantageous that the formulation can easily be modified to include temperature effects.
Atmos. Chem. Phys., 15, 7195-7202, doi:10.5194/acp-15-7195-2015, 2015
Fire emission heights in the climate system – Part 2: Impact on transport, black carbon concentrations and radiation
Summary: Global aerosol-climate models usually prescribe wildfire emission injections at fixed atmospheric levels. Here, we quantify the impact of prescribed and parametrized emission heights on aerosol long-range transport and radiation. For global emission height changes of 1.5-3.5km, we find a top-of-atmosphere radiative forcing of 0.05-0.1Wm-2. Replacing prescribed emission heights by a simple plume height parametrization only marginally improves the model performance in aerosol optical thickness.
Atmos. Chem. Phys., 15, 7173-7193, doi:10.5194/acp-15-7173-2015, 2015
Fire emission heights in the climate system – Part 1: Global plume height patterns simulated by ECHAM6-HAM2
Summary: We discuss the representation of wildfire emission heights in global climate models. Our implementation of a simple, semi-empirical plume height parametrization in the aerosol-climate model ECHAM6-HAM2 shows reasonable agreement with observations and with a more complex plume rise model. In contrast, prescribed emission heights, which do not consider the intensity of individual fires, fail to adequately simulate global plume height patterns. Diurnal and seasonal cycles are of minor importance.
Atmos. Chem. Phys., 15, 7155-7171, doi:10.5194/acp-15-7155-2015, 2015
LIVAS: a 3-D multi-wavelength aerosol/cloud database based on CALIPSO and EARLINET
Summary: LIVAS is a 3-D multi-wavelength global aerosol and cloud optical database optimized for future space-based lidar end-to-end simulations of realistic atmospheric scenarios as well as retrieval algorithm testing activities. The global database is based on CALIPSO observations at 532nm, while for the conversion at 355nm EARLINET data are utilized.
Atmos. Chem. Phys., 15, 7127-7153, doi:10.5194/acp-15-7127-2015, 2015
Top-down constraints on atmospheric mercury emissions and implications for global biogeochemical cycling
Summary: A better knowledge of mercury (Hg) emission fluxes into the global atmosphere is important for assessing its human health impacts and evaluating the effectiveness of corresponding policy actions. We for the first time apply a top-down approach at a global scale to quantitatively estimate present-day mercury emission sources as well as key parameters in a chemical transport model, in order to better constrain the global biogeochemical cycle of mercury.
Atmos. Chem. Phys., 15, 7103-7125, doi:10.5194/acp-15-7103-2015, 2015
In situ vertical profiles of aerosol extinction, mass, and composition over the southeast United States during SENEX and SEAC4RS: observations of a modest aerosol enhancement aloft
Summary: This paper investigates the summertime vertical profile of aerosol over the southeastern US using in situ measurements collected from aircraft. We use a vertical mixing model and measurements of CO to predict the vertical profile of aerosol that we would expect from vertical mixing alone and compare with the observed aerosol profile. We found a modest enhancement of aerosol in the cloudy transition layer during shallow cumulus convection and attribute the enhancement to local aerosol formation.
Atmos. Chem. Phys., 15, 7085-7102, doi:10.5194/acp-15-7085-2015, 2015
Middle East versus Saharan dust extinction-to-backscatter ratios
Atmos. Chem. Phys., 15, 7071-7084, doi:10.5194/acp-15-7071-2015, 2015
Estimating global and North American methane emissions with high spatial resolution using GOSAT satellite data
Atmos. Chem. Phys., 15, 7049-7069, doi:10.5194/acp-15-7049-2015, 2015
Balancing aggregation and smoothing errors in inverse models
Atmos. Chem. Phys., 15, 7039-7048, doi:10.5194/acp-15-7039-2015, 2015
Sulfur dioxide (SO2) from MIPAS in the upper troposphere and lower stratosphere 2002–2012
Atmos. Chem. Phys., 15, 7017-7037, doi:10.5194/acp-15-7017-2015, 2015
Simulation of the isotopic composition of stratospheric water vapour – Part 2: Investigation of HDO / H2O variations
Atmos. Chem. Phys., 15, 7003-7015, doi:10.5194/acp-15-7003-2015, 2015
Seasonal differences in oxygenated organic aerosol composition: implications for emissions sources and factor analysis
Atmos. Chem. Phys., 15, 6993-7002, doi:10.5194/acp-15-6993-2015, 2015
Lifted temperature minimum during the atmospheric evening transition
Summary: The study shows that lifted temperature minimum can be detected under calm conditions during the day-night transition, several hours earlier than reported in previous work. These conditions are fulfilled under weak synoptic forcing during local flow shifts associated with a mountain-plain complex orography. Under these special conditions, turbulence and radiation becomes a crucial parameter in determining the ideal conditions for observing LTM measurements.
Atmos. Chem. Phys., 15, 6981-6991, doi:10.5194/acp-15-6981-2015, 2015
Hydrogen peroxide in the marine boundary layer over the South Atlantic during the OOMPH cruise in March 2007
Atmos. Chem. Phys., 15, 6971-6980, doi:10.5194/acp-15-6971-2015, 2015
Sulfur-containing particles emitted by concealed sulfide ore deposits: an unknown source of sulfur-containing particles in the atmosphere
Summary: We collected particles carried by ascending flows and analysed them using transmission electron microscopy. Numerous sulfur-containing particles or particle aggregations were found in the ascending flows. In addition to S, the particles contained O, Ca, K, Mg, Fe, Na, Pb, Hg, Cu, Zn, As, Ti, Sr, Ba, etc. The sulfur-containing particles originated from deep-seated weathering or faulting products of concealed sulfide ore deposits. This is a previously unknown source of the atmospheric particles.
Atmos. Chem. Phys., 15, 6959-6969, doi:10.5194/acp-15-6959-2015, 2015
On the competition among aerosol number, size and composition in predicting CCN variability: a multi-annual field study in an urbanized desert
Atmos. Chem. Phys., 15, 6943-6958, doi:10.5194/acp-15-6943-2015, 2015
Estimates of non-traditional secondary organic aerosols from aircraft SVOC and IVOC emissions using CMAQ
Summary: Utilizing an aircraft-specific parameterization based on smog chamber data in a regional AQM, contributions of non-traditional secondary organic aerosols (NTSOA) from aircraft emissions of semi-volatile and intermediate volatility organic compounds were assessed. NTSOA, a previously unaccounted component of PM2.5 in most AQMs, contributed up to 7.4% of aviation-attributable PM2.5 at the airport and rose to 17.9% downwind, suggesting its significance in aviation-attributed PM2.5 at all scales.
Atmos. Chem. Phys., 15, 6929-6942, doi:10.5194/acp-15-6929-2015, 2015
Perturbations of the optical properties of mineral dust particles by mixing with black carbon: a numerical simulation study
Atmos. Chem. Phys., 15, 6913-6928, doi:10.5194/acp-15-6913-2015, 2015
Nonlinear response of modelled stratospheric ozone to changes in greenhouse gases and ozone depleting substances in the recent past
Summary: The attribution of stratospheric ozone (O3) loss in the recent past to increasing ozone depleting substances (ODSs) and greenhouse gases (GHGs) is important to verify the success of the Montreal Protocol. So far, nonlinearity in the O3 response to ODS and GHG changes has been mostly neglected. In this study we explicitly account for nonlinear O3 changes and aim to clarify their relevance in the past. We show that both O3 chemistry and transport are significantly affected by nonlinearity.
Atmos. Chem. Phys., 15, 6897-6911, doi:10.5194/acp-15-6897-2015, 2015
The 11-year solar cycle in current reanalyses: a (non)linear attribution study of the middle atmosphere
Summary: We have studied the solar cycle manifestation in the latest generation of the reanalysed data sets by the means of both linear and nonlinear attribution analyses. The study is supplemented by the discussion of the dynamical implications.
Atmos. Chem. Phys., 15, 6879-6895, doi:10.5194/acp-15-6879-2015, 2015
Chlorine isotope composition in chlorofluorocarbons CFC-11, CFC-12 and CFC-113 in firn, stratospheric and tropospheric air
Summary: Stratospheric ozone protects life on Earth from harmful UV-B radiation. Chlorofluorocarbons (CFCs) are man-made compounds which act to destroy this barrier. This paper presents (1) the first measurements of the stratospheric δ(37Cl) of CFCs -11 and -113; (2) the first quantification of long-term trends in the tropospheric δ(37Cl) of CFCs -11, -12 and -113. This study provides a better understanding of source and sink processes associated with these destructive compounds.
Atmos. Chem. Phys., 15, 6867-6877, doi:10.5194/acp-15-6867-2015, 2015
Heterogeneous reaction of peroxyacetic acid and hydrogen peroxide on ambient aerosol particles under dry and humid conditions: kinetics, mechanism and implications
Summary: The present study provides the first measurement for the uptake coefficient of gaseous peroxide compounds including peroxyacetic acid and hydrogen peroxide on the ambient particles (PM2.5 and Asian Storm Dust) over a wide range of relative humidity. The measured uptake coefficient values suggest that the heterogeneous reaction on the ambient particles plays an important role in the atmospheric budgets of peroxide compounds and potentially affects the components of aerosols in the atmosphere.
Atmos. Chem. Phys., 15, 6851-6866, doi:10.5194/acp-15-6851-2015, 2015
Seasonal variability of atmospheric nitrogen oxides and non-methane hydrocarbons at the GEOSummit station, Greenland
Atmos. Chem. Phys., 15, 6827-6849, doi:10.5194/acp-15-6827-2015, 2015
Unusual stratospheric ozone anomalies observed in 22 years of measurements from Lauder, New Zealand
Summary: This paper highlights 2 unusual mid-stratospheric O3 anomalies in our 22-year ground-based data set. One of these is a large month long increase in June 2001 which we are able to associate with very unusually low equatorial air which persists over Lauder for much of June. The other O3 anomaly persists for ~4 years; using MLS data, we show that this is associated with unusually high N2O during this period. During this period there is also a low O3 and N2O anomaly in the tropics.
Atmos. Chem. Phys., 15, 6817-6826, doi:10.5194/acp-15-6817-2015, 2015
Corrigendum to "Assessment of China's virtual air pollution transport embodied in trade by using a consumption-based emission inventory" published in Atmos. Chem. Phys., 15, 5443–5456, 2015
Atmos. Chem. Phys., 15, 6815-6815, doi:10.5194/acp-15-6815-2015, 2015
Regional data assimilation of multi-spectral MOPITT observations of CO over North America
Summary: We present a high-resolution (0.5 x 0.667) regional CO inversion over North America in the period of June 2004–May 2005, using a combination of GEOS-Chem model and MOPITT CO observations. With optimized lateral boundary conditions, we show that regional inversion analyses can reduce the sensitivity of the CO source estimates to errors in long-range transport and in the distributions of the hydroxyl radical (OH), and consequently, provide better quantification on regional CO source estimates.
Atmos. Chem. Phys., 15, 6801-6814, doi:10.5194/acp-15-6801-2015, 2015
Influence of biomass aerosol on precipitation over the Central Amazon: an observational study
Atmos. Chem. Phys., 15, 6789-6800, doi:10.5194/acp-15-6789-2015, 2015
Parameterization of convective transport in the boundary layer and its impact on the representation of the diurnal cycle of wind and dust emissions
Summary: New parameterizations of the convective boundary layer are used to better represent the diurnal cycle of near-surface wind over Sahara and Sahel in a climate model and the associated emission of dust.
Atmos. Chem. Phys., 15, 6775-6788, doi:10.5194/acp-15-6775-2015, 2015
The role of convective overshooting clouds in tropical stratosphere–troposphere dynamical coupling
Summary: The the role of deep convection in stratosphere–troposphere dynamical coupling in the tropics was studied during two large major stratospheric sudden warming events in January 2009 and January 2010. Convective activity and precipitation increased in the equatorial Southern Hemisphere as a result of a strengthening of the Brewer–Dobson circulation induced by enhanced stratospheric planetary wave activity.
Atmos. Chem. Phys., 15, 6767-6774, doi:10.5194/acp-15-6767-2015, 2015
Formation of highly oxidized multifunctional compounds: autoxidation of peroxy radicals formed in the ozonolysis of alkenes – deduced from structure–product relationships
Summary: We studied a series of cycloalkenes and methyl-substituted alkenes in order to elucidate the structural pre-requisites and chemical pathways to the recently discovered class of highly oxidized molecules ELVOC (Ehn et al., Nature, 2014). ELVOC may totally change the view on (parts of) the mechanism of SOA formation. We present results which support recent observations of H shifts from C-H to peroxy radicals, highlighting the pivotal role of peroxyradicals in organic atmospheric chemistry.
Atmos. Chem. Phys., 15, 6745-6765, doi:10.5194/acp-15-6745-2015, 2015
The POLARCAT Model Intercomparison Project (POLMIP): overview and evaluation with observations
Summary: Eleven 3-D tropospheric chemistry models have been compared and evaluated with observations in the Arctic during the International Polar Year (IPY 2008). Large differences are seen among the models, particularly related to the model chemistry of volatile organic compounds (VOCs) and reactive nitrogen (NOx, PAN, HNO3) partitioning. Consistency among the models in the underestimation of CO, ethane and propane indicates the emission inventory is too low for these compounds.
Atmos. Chem. Phys., 15, 6721-6744, doi:10.5194/acp-15-6721-2015, 2015
Vertical variation of optical properties of mixed Asian dust/pollution plumes according to pathway of air mass transport over East Asia
Summary: The measurements from 2009 to 2013 using a multiwavelength Raman lidar were conducted to identify the changes in optical properties of East Asian dust. We found that the optical properties of Asian dust change depending on the dust plume's vertical position and the change of vertical position during transport over China. We believe this paper provides a better understanding of the optical properties of mixed Asian dust plums and the effect of long-range transport on dust properties.
Atmos. Chem. Phys., 15, 6707-6720, doi:10.5194/acp-15-6707-2015, 2015
Formaldehyde (HCHO) in air, snow, and interstitial air at Concordia (East Antarctic Plateau) in summer
Summary: During two austral summers HCHO was investigated in air, snow, and interstitial air at the Concordia site located on the East Antarctic Plateau. Snow emission fluxes were estimated to be around 1 to 2 and 3 to 5 x 10^12 molecules m-2 s-1 at night and at noon, respectively. Shading experiments suggest that the photochemical HCHO production in the snowpack at Concordia remains negligible. The mean HCHO level of 130pptv observed at 1m above the surface is quite well reproduced by 1-D simulations.
Atmos. Chem. Phys., 15, 6689-6705, doi:10.5194/acp-15-6689-2015, 2015
Investigating the links between ozone and organic aerosol chemistry in a biomass burning plume from a prescribed fire in California chaparral
Summary: Being able to understand and simulate the chemical evolution of biomass burning smoke plumes under a wide variety of conditions is a critical part of forecasting the impact of these fires on air quality, atmospheric composition, and climate. Here we use an improved model of this chemistry to simulate the evolution of ozone and secondary organic aerosol within a young biomass burning smoke plume from the Williams prescribed burn in chaparral, which was sampled over California in November 2009.
Atmos. Chem. Phys., 15, 6667-6688, doi:10.5194/acp-15-6667-2015, 2015
Lagrangian analysis of microphysical and chemical processes in the Antarctic stratosphere: a case study
Summary: We investigated chemical and microphysical processes in the late winter Antarctic stratosphere, for the first time (to our knowledge) coupling a detailed microphysical box model to a chemistry model. Model results have been compared with in situ and remote sensing measurements of particles along trajectories. Our goal is to contribute to the most recent discussion of the relative role of PSC and liquid (background) aerosol in the ozone depletion.
Atmos. Chem. Phys., 15, 6651-6665, doi:10.5194/acp-15-6651-2015, 2015
Estimating NH3 emissions from agricultural fertilizer application in China using the bi-directional CMAQ model coupled to an agro-ecosystem model
Summary: In this study, we estimate, for the first time, the NH3 emission from the agricultural fertilizer application in China online using the bi-directional CMAQ model coupled to an agro-ecosystem model. Compared with previous researches, this method considers more influencing factors, such as meteorological fields, soil and the fertilizer application, and provides improved NH3 emission with higher spatial and temporal resolution.
Atmos. Chem. Phys., 15, 6637-6649, doi:10.5194/acp-15-6637-2015, 2015
Characteristics of 1 year of observational data of VOCs, NOx and O3 at a suburban site in Guangzhou, China
Atmos. Chem. Phys., 15, 6625-6636, doi:10.5194/acp-15-6625-2015, 2015
Enhanced extinction of visible radiation due to hydrated aerosols in mist and fog
Atmos. Chem. Phys., 15, 6605-6623, doi:10.5194/acp-15-6605-2015, 2015
Influence of along-valley terrain heterogeneity on exchange processes over idealized valleys
Atmos. Chem. Phys., 15, 6589-6603, doi:10.5194/acp-15-6589-2015, 2015
Momentum forcing of the quasi-biennial oscillation by equatorial waves in recent reanalyses
Summary: The momentum forcing of the stratospheric quasi-biennial oscillation (QBO) by equatorial waves is estimated using recent reanalysis data sets. The Kelvin wave produces primary forcing of the QBO in the easterly-to-westerly transition phase below 30hPa, whereas mesoscale gravity waves produce larger forcing than the Kelvin wave above 30hPa. Still, the recent reanalyses underestimate the forcing by the large-scale equatorial waves.
Atmos. Chem. Phys., 15, 6577-6587, doi:10.5194/acp-15-6577-2015, 2015
Using IASI to simulate the total spectrum of outgoing long-wave radiances
Atmos. Chem. Phys., 15, 6561-6575, doi:10.5194/acp-15-6561-2015, 2015
Modelling the impact of climate change on the atmospheric transport and the fate of persistent organic pollutants in the Arctic
Atmos. Chem. Phys., 15, 6549-6559, doi:10.5194/acp-15-6549-2015, 2015
Impact of interannual variations in sources of insoluble aerosol species on orographic precipitation over California's central Sierra Nevada
Summary: Aerosols impact how clouds and precipitation form. In the California Sierra Nevada, we found that the formation and resulting amount of rain and snow were impacted by mineral dust, bioparticles such as bacteria, and biomass burning and pollution particles during three winter seasons. Dust and bioparticles from distant sources impacted high-altitude clouds by forming ice, leading to more precipitation, whereas local biomass burning and pollution entered the base of clouds, leading to less rain.
Atmos. Chem. Phys., 15, 6535-6548, doi:10.5194/acp-15-6535-2015, 2015
Regional differences in Chinese SO2 emission control efficiency and policy implications
Summary: SO2 emission reduction over North China is most effective in reducing national mean surface sulfate concentrations and sulfur export fluxes (β = 0.76 and 0.95, respectively), while reduction over South China has the highest β in reducing population-weighted sulfate concentration (β = 0.98). We recommend that China needs to carefully design a regionally specific implementation plan of realizing its SO2 emissions reduction target to maximize the resulting air quality benefits.
Atmos. Chem. Phys., 15, 6521-6533, doi:10.5194/acp-15-6521-2015, 2015
Particulate emissions from residential wood combustion in Europe – revised estimates and an evaluation
Summary: Residential wood combustion (RWC) is increasing in Europe but may cause high emissions of particulate matter (PM). A revised bottom-up emission inventory was made which included the semi-volatile components. The revised RWC emissions are 2–3 times higher than the previous inventory. It significantly improved the modeling of PM and comparison with observations. Our results suggest primary PM2.5 emission from RWC as reported in Europe is underestimated and emission inventories need to be revised.
Atmos. Chem. Phys., 15, 6503-6519, doi:10.5194/acp-15-6503-2015, 2015
Potential source regions and processes of aerosol in the summer Arctic
Summary: Particle size distributions from four summer cruises of the Swedish icebreaker Oden were combined with back trajectories and pack ice information in a cluster algorithm to investigate source areas and aerosol formation in the central Arctic. Five source regions and three aerosol types resulted. Long travel times over ice, combined with more open water conditions shortly before air mass arrival, seem to control the formation of ultrafine particles over the central Arctic pack ice.
Atmos. Chem. Phys., 15, 6487-6502, doi:10.5194/acp-15-6487-2015, 2015
The impact of overshooting deep convection on local transport and mixing in the tropical upper troposphere/lower stratosphere (UTLS)
Summary: This study examines the simulated downward transport and mixing of stratospheric air into the upper tropical troposphere as observed on a research flight during the SCOUT-O3 campaign in connection with a deep convective system, using the WRF model. Passive tracers are initialised to study the impact of the deep convection on the tracers and water vapour. We use the model to explain the processes causing the transport and also expose areas of inconsistencies between the model and observations.
Atmos. Chem. Phys., 15, 6467-6486, doi:10.5194/acp-15-6467-2015, 2015
Survival and ice nucleation activity of bacteria as aerosols in a cloud simulation chamber
Summary: Mortality rate of typical bacterial aerosols (Pseudomonas species) was determined in a cloud simulation chamber. Ice nucleation activity remained unchanged for several hours in aerosolized cells, whether they were viable or not. Cloud increased the specific removal of ice nucleation active cells by precipitation. Survival was negatively impacted by the presence of cloud and by sulfates.
Atmos. Chem. Phys., 15, 6455-6465, doi:10.5194/acp-15-6455-2015, 2015
A 12-year observation of water-soluble ions in TSP aerosols collected at a remote marine location in the western North Pacific: an outflow region of Asian dust
Atmos. Chem. Phys., 15, 6437-6453, doi:10.5194/acp-15-6437-2015, 2015
An evaluation of ozone dry deposition in global scale chemistry climate models
Summary: The dry deposition of ozone to the Earth's surface is an important process as it controls both the removal of this potent pollutant from the atmosphere and its uptake by vegetation. It is necessary to use numerical models to study this process at the global scale, but many models to represent dry deposition lag behind current understanding. In this paper we study the dry deposition process in global models and highlight measures that will allow these models to be critically evaluated.
Atmos. Chem. Phys., 15, 6419-6436, doi:10.5194/acp-15-6419-2015, 2015
Aerosols over continental Portugal (1978–1993): their sources and an impact on the regional climate
Summary: The aerosols sources (volcanoes, mineral dust, wildfires, pollution) in continental Portugal were studied using ground and satellite measurements. The influence of the each source changes with the season and environment. Concerning the effect that aerosols have over the local climate variations change, the strongest influence was found for the less urbanized site and for the summer months. It consists in dependence of the maximum daily temperature variations on the absorbing aerosol content.
Atmos. Chem. Phys., 15, 6407-6418, doi:10.5194/acp-15-6407-2015, 2015
Quantifying methane and nitrous oxide emissions from the UK and Ireland using a national-scale monitoring network
Summary: The UK is one of several countries to enact legislation to reduce its greenhouse gas emissions. We present top-down emissions of methane and nitrous oxide for the UK and Ireland over 2012-2014. We inferred average UK emissions of 2.09Tg/yr CH4 and 0.101Tg/yr N2O and used sectoral distributions to determine whether these discrepancies can be attributed to specific source sectors. We found the agricultural sector likely to be overestimated in the bottom-up emissions inventories of both gases.
Atmos. Chem. Phys., 15, 6393-6406, doi:10.5194/acp-15-6393-2015, 2015
Chemical characterization of submicron regional background aerosols in the western Mediterranean using an Aerosol Chemical Speciation Monitor
Summary: The study focuses on the aerosol variations found in the regional background of the western Mediterranean basin and their relation with atmospheric conditions and scenarios. An Aerosol Chemical Speciation Monitor (ACSM) was deployed for 1 year and the results were validated with co-located PM1 measurements. The organic sources were investigated and the local secondary organic aerosol (SOA) formation was estimated.
Atmos. Chem. Phys., 15, 6379-6391, doi:10.5194/acp-15-6379-2015, 2015
Impacts of 20th century aerosol emissions on the South Asian monsoon in the CMIP5 models
Atmos. Chem. Phys., 15, 6367-6378, doi:10.5194/acp-15-6367-2015, 2015
Investigating the annual behaviour of submicron secondary inorganic and organic aerosols in London
Summary: For the first time, the behaviour of non-refractory inorganic and organic submicron particulates through an entire annual cycle is investigated at a UK urban background site. We show secondary aerosols account for a significant fraction of the submicron aerosol burden, high concentration events are governed by different factors depending on season, and on an annual basis there is no variability in the extent of secondary organic aerosol oxidation.
Atmos. Chem. Phys., 15, 6351-6366, doi:10.5194/acp-15-6351-2015, 2015
The role of organic condensation on ultrafine particle growth during nucleation events
Summary: A new aerosol dynamics model (DMANx) describing the organic vapor condensation on nanoparticles based on the volatility basis set framework is used to simulate typical nucleation events in two contrasting environments in Hyytiälä (Finland) and Finokalia (Greece). The role of semivolatile, low, and extremely low volatility organics and the corresponding surface energies is investigated.
Atmos. Chem. Phys., 15, 6337-6350, doi:10.5194/acp-15-6337-2015, 2015
Observations and analysis of organic aerosol evolution in some prescribed fire smoke plumes
Summary: Smoke plumes from some prescribed fires in the southeastern United States were sampled via aircraft to observe changes in organic aerosol (OA) with atmospheric transport. These plumes underwent rapid mixing, and, hence, substantial dilution with background air occurred. Dilution-driven evaporation appears to be the primary driver of OA transformations within the sampled plumes rather than photochemistry.
Atmos. Chem. Phys., 15, 6323-6335, doi:10.5194/acp-15-6323-2015, 2015
Connecting the solubility and CCN activation of complex organic aerosols: a theoretical study using solubility distributions
Summary: Atmospheric organic aerosol is complex and thus a challenge to model. We introduce a theoretical framework (solubility distributions) to represent the solubility of multicomponent mixtures. Using the framework, we evaluate the commonly made assumptions about the cloud condensation nucleus (CCN) activity of organic mixtures. We find that material with water solubilities larger than 0.1-100 g/L can usually be treated as completely soluble, which simplifies the treatment of organic CCN.
Atmos. Chem. Phys., 15, 6305-6322, doi:10.5194/acp-15-6305-2015, 2015
A large and ubiquitous source of atmospheric formic acid
Summary: Formic acid (HCOOH) is an abundant atmospheric acid that affects precipitation chemistry and acidity. HCOOH measurements over the USA are 2-3× larger than can be explained by known sources and sinks, revealing a key gap in current understanding. Observations indicate a large biogenic source plus chemical production across a range of precursors. Model simulations cannot capture the HCOOH diurnal amplitude or nocturnal profile, implying a deposition bias and possibly even larger missing source.
Atmos. Chem. Phys., 15, 6283-6304, doi:10.5194/acp-15-6283-2015, 2015
Meridionally tilted ice cloud structures in the tropical upper troposphere as seen by CloudSat
Summary: Upper-tropospheric ice clouds (anvil and cirrus cloud ouflows extending from deep convection) have small-scale (~1km horizontal) structures that are organized and systematically tilt poleward in the tropics, as revealed by CloudSat ice water path (IWP) and Aura MLS Radiance (TB) measurements. These tilted cloud structures cover regions over hundreds of kilometers, contributing up to 20% of IWP uncertainty if not accounted for in remote sensing from space.
Atmos. Chem. Phys., 15, 6271-6281, doi:10.5194/acp-15-6271-2015, 2015
Sources, transport and deposition of iron in the global atmosphere
Summary: This study makes a first attempt to estimate the temporal trend of Fe emissions from anthropogenic and natural combustion sources from 1960 to 2007 and the emissions of Fe from mineral dust based on a recent mineralogical database. The new emission inventory is introduced into a global aerosol model. The simulated total Fe and soluble Fe concentrations in surface air as well as the deposition of total Fe are evaluated by observations over major continental and oceanic regions globally.
Atmos. Chem. Phys., 15, 6247-6270, doi:10.5194/acp-15-6247-2015, 2015
A case study of a low-level jet during OPALE
Summary: This is the first time that a low-level jet observed above the East Antarctic Plateau is simulated by a regional climate model. This paper illustrates in a 3-D simulation the respective influences of the large-scale pressure gradient force and turbulence on the onset of the low-level jet. As atmospheric turbulence plays a key role in explaining the behaviour of chemical tracers during the OPALE campaign, this paper also increases our confidence in using the outputs of the model for this purpose.
Atmos. Chem. Phys., 15, 6237-6246, doi:10.5194/acp-15-6237-2015, 2015
Characterization of the boundary layer at Dome C (East Antarctica) during the OPALE summer campaign
Summary: Regional climate model MAR was run for the region of Dome C located on the East Antarctic plateau, during summer 2011–2012, with a high vertical resolution in the lower troposphere. MAR is generally in very good agreement with the observations and provides sufficiently reliable information about surface turbulent fluxes and vertical profiles of vertical diffusion coefficients when discussing the representativeness of chemical measurements made nearby the ground surface at Dome C.
Atmos. Chem. Phys., 15, 6225-6236, doi:10.5194/acp-15-6225-2015, 2015
Quantifying sources, transport, deposition, and radiative forcing of black carbon over the Himalayas and Tibetan Plateau
Summary: We use the CAM5 model with a novel source-tagging technique to characterize the fate of BC particles emitted from various geographical regions and sectors and their transport pathways to the Himalayas and Tibetan Plateau (HTP). We show a comprehensive picture of the seasonal and regional dependence of BC source attributions, and find strong seasonal and spatial variations in BC-in-snow radiative forcing in the HTP that can be quantitatively attributed to the various regional/sectoral sources.
Atmos. Chem. Phys., 15, 6205-6223, doi:10.5194/acp-15-6205-2015, 2015
Arctic microbial and next-generation sequencing approach for bacteria in snow and frost flowers: selected identification, abundance and freezing nucleation
Summary: Next-generation sequencing revealed the existence of diverse community of bacteria in the Arctic samples with many originating from distinct ecological environments. The observed varied range in ice nucleation of cultivable bacteria and in all of the melted samples further revealed the existence of the heterogeneous pool of bacteria. Changes in the microbial pool and its impact on the freezing and melting process may potentially lead to changing the Arctic environment and thus global climate.
Atmos. Chem. Phys., 15, 6183-6204, doi:10.5194/acp-15-6183-2015, 2015
Ozone and aerosol tropospheric concentrations variability analyzed using the ADRIMED measurements and the WRF and CHIMERE models
Summary: The ozone and aerosol concentration variability is studied over the Euro-Mediterranean area during the months of June and July 2013 and in the framework of the ADRIMED project. A first analysis is performed using meteorological variables, ozone and aerosol concentrations using routine network station, satellite and specific ADRIMED project airborne measurements. This analysis is complemented by modeling using the WRF and CHIMERE regional models.
Atmos. Chem. Phys., 15, 6159-6182, doi:10.5194/acp-15-6159-2015, 2015
The importance of interstitial particle scavenging by cloud droplets in shaping the remote aerosol size distribution and global aerosol-climate effects
Summary: In this paper we show that coagulation of cloud droplets with interstitial aerosol particles, a process often neglected in atmospheric aerosol models, has a significant impact on aerosol size distributions and radiative forcings.
Atmos. Chem. Phys., 15, 6147-6158, doi:10.5194/acp-15-6147-2015, 2015
Regional-scale simulations of fungal spore aerosols using an emission parameterization adapted to local measurements of fluorescent biological aerosol particles
Atmos. Chem. Phys., 15, 6127-6146, doi:10.5194/acp-15-6127-2015, 2015
Ice crystal concentrations in wave clouds: dependencies on temperature, D > 0.5 μm aerosol particle concentration, and duration of cloud processing
Summary: The study analyzes a novel set of cloud measurements relevant to the genesis of atmospheric ice particles. Issues addressed are 1) the DeMott et al. (2010) formula describing the abundance of ice nucleating particles and the degree to which that formula is consistent with our in situ measurements, 2) the discrepancy between the DeMott et al. formula and measurements made in the AIDA chamber in Karlsruhe, Germany (Niemand et al., 2012), and 3) the time dependence of atmospheric ice nucleation.
Atmos. Chem. Phys., 15, 6113-6125, doi:10.5194/acp-15-6113-2015, 2015
Examining the major contributors of ozone pollution in a rural area of the Yangtze River Delta region during harvest season
Atmos. Chem. Phys., 15, 6101-6111, doi:10.5194/acp-15-6101-2015, 2015
Photochemical processing of aqueous atmospheric brown carbon
Summary: Aqueous-phase photochemical decay of light absorbing organic compounds, or atmospheric brown carbon (BrC), is investigated in this study. The absorptive change of laboratory surrogates of BrC, as well as biofuel combustion samples, were monitored during photolysis and OH oxidation experiments. The major finding is the rapid change in the absorptivity of BrC during such photochemical processing. This change should be taken into account to evaluate the importance of BrC in the atmosphere.
Atmos. Chem. Phys., 15, 6087-6100, doi:10.5194/acp-15-6087-2015, 2015
Increasing and decreasing trends of the atmospheric deposition of organochlorine compounds in European remote areas during the last decade
Summary: Despite the regulations in the use of polychlorobiphenyls (PCBs), an increase in atmospheric deposition fluxes of these pollutants in high-altitude mountain areas of Europe is observed for the period between 1996 and 2006. In contrast, atmospheric deposition of organochlorine pesticides showed a strong decrease. Volatilization from soils or melting glaciers related to climate change and the differences in physical–chemical properties between compounds may explain the observed temporal trend.
Atmos. Chem. Phys., 15, 6069-6085, doi:10.5194/acp-15-6069-2015, 2015
Biomass burning influence on high-latitude tropospheric ozone and reactive nitrogen in summer 2008: a multi-model analysis based on POLMIP simulations
Summary: The extent to which forest fires produce the air pollutant and greenhouse gas ozone (O3) in the atmosphere at high latitudes in not well understood. We have compared how fire emissions produce O3 and its precursors in several models of atmospheric chemistry. We find enhancements in O3 in air dominated by fires in all models, which increase on average as fire emissions age. We also find that in situ O3 production in the Arctic is sensitive to details of organic chemistry and vertical lifting.
Atmos. Chem. Phys., 15, 6047-6068, doi:10.5194/acp-15-6047-2015, 2015
Formation and chemical aging of secondary organic aerosol during the β-caryophyllene oxidation
Atmos. Chem. Phys., 15, 6035-6046, doi:10.5194/acp-15-6035-2015, 2015
Aerosol composition and sources during the Chinese Spring Festival: fireworks, secondary aerosol, and holiday effects
Summary: Aerosol composition and sources during the Chinese spring festival are characterized in detail. The roles of fireworks and secondary aerosol in fine particle pollution were elucidated. We observed large reductions of primary species, whereas changes of secondary aerosol during the holiday period were minor. This has significant implications; reducing primary emissions on a local scale during severe haze episodes might have a limited effect on improving air quality in megacities.
Atmos. Chem. Phys., 15, 6023-6034, doi:10.5194/acp-15-6023-2015, 2015
Atmospheric brown clouds reach the Tibetan Plateau by crossing the Himalayas
Summary: The Himalayas and the Tibetan Plateau region (HTP) is regularly exposed to polluted air masses that might influence glaciers as well as climate on regional to global scales. We found that atmospheric brown clouds from South Asia reach the HTP by crossing the Himalayas not only through the major north--south river valleys but rather over large areas by being lifted and advected at mid-troposheric levels. The transport is enabled by a combination of synoptic and local meteorological settings.
Atmos. Chem. Phys., 15, 6007-6021, doi:10.5194/acp-15-6007-2015, 2015