On the derivation of particle nucleation rates from experimental formation rates
Summary: The manuscript provides insights into the calculation of new particle formation rates. Generally, formation rates are measured at a diameter which can be substantially larger than the critical size of the newly formed particles. In order to transform the formation rate to a smaller size, a correction needs to be applied. We present a new method to apply this correction which takes into account the effect of self-coagulation.
Atmos. Chem. Phys., 15, 4063-4075, doi:10.5194/acp-15-4063-2015, 2015
Aerosol optical hygroscopicity measurements during the 2010 CARES campaign
Summary: This work describes an analysis of measurements of the influence of water uptake on the light-scattering properties of sub- and supermicron-sized particles as observed in the Sacramento, CA, USA region during the 2010 CARES field campaign. The observations are used to derive campaign-average effective hygroscopicity parameters for submicron oxygenated organic aerosol and for supermicron particles, and the influence of chloride displacement reactions on particle hygroscopicity is examined.
Atmos. Chem. Phys., 15, 4045-4061, doi:10.5194/acp-15-4045-2015, 2015
Corrigendum to "Photosensitised heterogeneous oxidation kinetics of biomass burning aerosol surrogates by ozone using an irradiated rectangular channel flow reactor" published in Atmos. Chem. Phys., 13, 6507–6522, 2013
Atmos. Chem. Phys., 15, 4043-4043, doi:10.5194/acp-15-4043-2015, 2015
Trends and drivers of ozone human health and vegetation impact metrics from UK EMEP supersite measurements (1990–2013)
Summary: Health- and vegetation-relevant ozone exposure metrics (SOMO10/SOMO35 and PODY/AOT40 respectively) are analysed between 1990 and 2013 using data from the UK EMEP supersites: Auchencorth Moss, southern Scotland and Harwell, south-east England. Analysis shows that for health-relevant ozone exposure, improvement has been achieved for SOMO35 but not for SOMO10 despite European mitigation strategies reducing precursor emissions. Vegetation impacts based on PODY have also not decreased.
Atmos. Chem. Phys., 15, 4025-4042, doi:10.5194/acp-15-4025-2015, 2015
The MACC-II 2007–2008 reanalysis: atmospheric dust evaluation and characterization over northern Africa and the Middle East
Summary: Atmospheric mineral dust from a MACC-II short reanalysis (2007-2008) has been evaluated over northern Africa and the Middle East using satellite aerosol products, AERONET data, in situ PM10 concentrations, and extinction vertical profiles. The MACC-II AOD spatial and temporal variability shows good agreement with satellite sensors and AERONET. We find a good agreement in averaged extinction vertical profiles between MACC-II and lidars. MACC correctly reproduces daily to interannual PM10.
Atmos. Chem. Phys., 15, 3991-4024, doi:10.5194/acp-15-3991-2015, 2015
Evaluation of the GEM-AQ model in the context of the AQMEII Phase 1 project
Summary: In the scope of the AQMEII Phase 1 project the GEM-AQ model was run over Europe for the year 2006 with a resolution of 0.2 × 0.2 degrees. Spatial distribution and temporal variability of the GEM-AQ model results were analyzed for surface ozone and PM10 concentrations in the context of regional climate characteristics. The GEM-AQ model performance was characterized for station types, European climatic regions, and seasons.
Atmos. Chem. Phys., 15, 3971-3990, doi:10.5194/acp-15-3971-2015, 2015
Radiative forcing and climate metrics for ozone precursor emissions: the impact of multi-model averaging
Summary: This study examines quantitatively the impact of methodological choices, in particular of averaging of multi-model ensembles, on climate metrics for ozone precursors. Estimates of the standard deviation of radiative forcing (RF), global warming and temperature potential (GWP, GTP) from ensemble-mean input fields generally overestimate the true value. The multi-model average fields are appropriate for calculating mean metrics, but are not a reliable method for calculating the uncertainty.
Atmos. Chem. Phys., 15, 3957-3969, doi:10.5194/acp-15-3957-2015, 2015
Dimensions and aspect ratios of natural ice crystals
Summary: Dimensions of ice crystals increased with an increase in temperature and the L-W relationships of crystals with a given L depended heavily on temperature, whereas the aspect ratio depended only weakly on temperature. The relative frequency of occurrence of plates was much larger in anvil clouds compared to that of columnar crystals (i.e., columns and bullet rosettes), whereas the relative occurrence frequency of columnar crystals was much larger in non-anvil clouds.
Atmos. Chem. Phys., 15, 3933-3956, doi:10.5194/acp-15-3933-2015, 2015
Simulations of atmospheric OH, O3 and NO3 reactivities within and above the boreal forest
Atmos. Chem. Phys., 15, 3909-3932, doi:10.5194/acp-15-3909-2015, 2015
Spatial and temporal variation in CO over Alberta using measurements from satellites, aircraft, and ground stations
Summary: This study demonstrated the potential use of MOPITT CO measurements to better understand the CO sources over Alberta. The climatological time curtain plot and spatial maps for CO over northern Alberta indicate the signatures of transported CO for two distinct biomass burning seasons: summer and spring. Northern Alberta shows stronger upward lifting motion which leads to larger CO total column values, while the poor dispersion in central and southern Alberta exacerbates the surface CO pollution.
Atmos. Chem. Phys., 15, 3893-3908, doi:10.5194/acp-15-3893-2015, 2015
Comparisons of polar processing diagnostics from 34 years of the ERA-Interim and MERRA reanalyses
Summary: We use a comprehensive set of diagnostics to investigate how two widely used modern reanalysis data sets might affect studies of lower stratospheric polar processing and ozone loss. Our results show that the agreement in temperature diagnostics between the two reanalyses improves over time in both hemispheres with increasing assimilation model inputs. This suggests that both data sets are appropriate choices for studies of polar processing in recent winters.
Atmos. Chem. Phys., 15, 3873-3892, doi:10.5194/acp-15-3873-2015, 2015
Determination of interfacial parameters of a soluble particle in a nonideal solution from measured deliquescence and efflorescence humidities
Summary: To study the growth/shrinking of a hygroscopic nanoparticle during hydration/dehydration in an atmosphere of water vapour we employed a thermodynamic approach. For application to a nanometric sodium chloride particle we extended the original approach and demonstrated how the solution/solute interface energy and the correlation length of a thin solution film can be determined from a combination of experimentally determinable efflorescence and deliquescence humidities with the present calculus.
Atmos. Chem. Phys., 15, 3851-3871, doi:10.5194/acp-15-3851-2015, 2015
Transport of anthropogenic and biomass burning aerosols from Europe to the Arctic during spring 2008
Atmos. Chem. Phys., 15, 3831-3850, doi:10.5194/acp-15-3831-2015, 2015
CCN activation of fumed silica aerosols mixed with soluble pollutants
Atmos. Chem. Phys., 15, 3815-3829, doi:10.5194/acp-15-3815-2015, 2015
Revisiting Twomey's approximation for peak supersaturation
Summary: A new parametrization for cloud droplet nucleation is described. This revised approach makes use of a simple look-up table which is very efficient and computationally very cheap. Adopting this approach further allows for a more accurate treatment of the necessary approximations of supersaturation evolution and ultimately leads to a more accurate calculation of peak supersaturation and hence droplet nucleation.
Atmos. Chem. Phys., 15, 3803-3814, doi:10.5194/acp-15-3803-2015, 2015
High-resolution observations of the near-surface wind field over an isolated mountain and in a steep river canyon
Summary: Interest in numerical wind models continues to increase, especially for models that can simulate winds at relatively high spatial resolution (~100m). However, limited observational data exist for evaluation of model predictive performance. This study presents high-resolution surface wind data sets collected from an isolated mountain and a steep river canyon. The data are available to the public at http://www.firemodels.org/index.php/windninja-introduction/windninja-publications.
Atmos. Chem. Phys., 15, 3785-3801, doi:10.5194/acp-15-3785-2015, 2015
Atmospheric oxidation of isoprene and 1,3-butadiene: influence of aerosol acidity and relative humidity on secondary organic aerosol
Summary: This work explores the impact of acidic sulfate aerosol on the formation of SOA from isoprene and 1,3-butadiene. This study expands on previous work by extending the analysis over a broader range of humidities and aerosol liquid water contents. Extending the experiments to a wider range of hydrocarbons and across a more realistic range of humidities provides data of greater atmospheric relevance and contributes to development of acidity-influenced SOA chemistry mechanisms in air quality models.
Atmos. Chem. Phys., 15, 3773-3783, doi:10.5194/acp-15-3773-2015, 2015
Monsoonal variations in aerosol optical properties and estimation of aerosol optical depth using ground-based meteorological and air quality data in Peninsular Malaysia
Summary: Southeast Asia stands out globally, as it hosts one of the most complex meteorological and environmental conditions, making remote sensing difficult both for AERONET and satellites. Cloud-cleared data leave gaps in our remote sensing data record, and conversely, residual cloud contamination of remotely sensed data causes challenging tasks for scientists studying aerosols. With the main motivation of overcoming this problem, an AOD-predicting model is proposed.
Atmos. Chem. Phys., 15, 3755-3771, doi:10.5194/acp-15-3755-2015, 2015
Methane as a diagnostic tracer of changes in the Brewer–Dobson circulation of the stratosphere
Summary: Time series of the satellite-observed stratospheric tracer, CH4, are analyzed to see whether they indicate a significant trend for the hemispheric Brewer--Dobson circulation (BDC) for 1992-2005. Trends in CH4 for the lower stratosphere are generally positive and equivalent to those of the troposphere. However, the Northern Hemisphere BDC is clearly accelerated in the mid-stratosphere (20 to 7hPa). Corresponding trends for the Southern Hemisphere are smaller and less significant.
Atmos. Chem. Phys., 15, 3739-3754, doi:10.5194/acp-15-3739-2015, 2015
Observations and comparisons of cloud microphysical properties in spring and summertime Arctic stratocumulus clouds during the ACCACIA campaign
Summary: Measurements of cloud microphysics are reported from the Aerosol-Cloud Coupling And Climate Interactions (ACCACIA) campaign. Concentrations of ice particles from two spring and two summer cases are compared with particular attention to the role of secondary ice in these clouds. In addition aerosol measurements were used as input to a primary ice nucleation parameterisation which was compared with observed values of primary ice in these clouds. We found higher concentrations of ice during summer.
Atmos. Chem. Phys., 15, 3719-3737, doi:10.5194/acp-15-3719-2015, 2015
A new temperature- and humidity-dependent surface site density approach for deposition ice nucleation
Summary: Ice nucleation in clouds has a significant influence on the global radiative budget and the hydrological cycle. Several studies have investigated the ice formation in droplets and parameterizations have been developed in order to include immersion freezing in climate models. In contrast, there are fewer studies regarding the conversion of water vapor into ice (so-called deposition nucleation) which is the topic of this paper which investigates deposition nucleation by Arizona Test dust in detail
Atmos. Chem. Phys., 15, 3703-3717, doi:10.5194/acp-15-3703-2015, 2015
Submicron particle mass concentrations and sources in the Amazonian wet season (AMAZE-08)
Summary: Submicron particle mass concentration in the Amazon during the wet season of 2008 was dominated by organic material. The PMF analysis finds a comparable importance of gas-phase (gas-to-particle condensation) and particle-phase (reactive uptake of isoprene oxidation products, especially of epoxydiols to acidic haze, fog, or cloud droplets) production of secondary organic material during the study period, together accounting for >70% of the organic-particle mass concentration.
Atmos. Chem. Phys., 15, 3687-3701, doi:10.5194/acp-15-3687-2015, 2015
Simultaneous reductions in emissions of black carbon and co-emitted species will weaken the aerosol net cooling effect
Summary: This study highlights that there are no effective ways to remove the black carbon exclusively without influencing the other co-emitted components, our results therefore indicate that a reduction in BC emission can lead to an unexpected warming on the Earth’s climate system in the future.
Atmos. Chem. Phys., 15, 3671-3685, doi:10.5194/acp-15-3671-2015, 2015
OH populations and temperatures from simultaneous spectroscopic observations of 25 bands
Summary: We discuss a high-quality data set of simultaneous observations of 25 OH bands with an astronomical echelle spectrograph. These data allowed us to analyse band-dependent OH populations and temperatures. In particular, we could find different non-LTE contributions to OH rotational temperatures depending on band, line set, and observing time. This is critical for mesopause studies that use these temperatures as a proxy of the true temperatures.
Atmos. Chem. Phys., 15, 3647-3669, doi:10.5194/acp-15-3647-2015, 2015
Chemical characterization of biogenic secondary organic aerosol generated from plant emissions under baseline and stressed conditions: inter- and intra-species variability for six coniferous species
Atmos. Chem. Phys., 15, 3629-3646, doi:10.5194/acp-15-3629-2015, 2015
The effects of springtime mid-latitude storms on trace gas composition determined from the MACC reanalysis
Summary: Novel use of combined meteorology and composition reanalysis data and compositing methodologies to characterize pollutant distributions of ozone (O3) and carbon monoxide (CO) in "typical" intense springtime storms versus the background environment for the period 2003--2012. Clear signals of O3 and CO redistributed horizontally and vertically throughout storms. In particular, the lofting of CO-rich/O3-poor air in the warm conveyor belt and the descent of O3-rich/CO-poor air in the dry intrusion.
Atmos. Chem. Phys., 15, 3605-3628, doi:10.5194/acp-15-3605-2015, 2015
Multi-model study of chemical and physical controls on transport of anthropogenic and biomass burning pollution to the Arctic
Summary: Multi-model simulations of Arctic CO, O3 and OH are evaluated using observations. Models show highly variable concentrations but the relative importance of emission regions and types is robust across the models, demonstrating the importance of biomass burning as a source. Idealised tracer experiments suggest that some of the model spread is due to variations in simulated transport from Europe in winter and from Asia throughout the year.
Atmos. Chem. Phys., 15, 3575-3603, doi:10.5194/acp-15-3575-2015, 2015
Rapid transport of East Asian pollution to the deep tropics
Summary: We use observations and model calculations to show that "cold surges" occurring during Northern Hemisphere winter can rapidly transport East Asian pollution to equatorial Southeast Asia. As well as affecting atmospheric composition near the surface, we argue that strong convection can subsequently lift the polluted air masses to the tropical upper troposphere. This suggests a potentially important connection between midlatitude pollution sources and the lower stratosphere.
Atmos. Chem. Phys., 15, 3565-3573, doi:10.5194/acp-15-3565-2015, 2015
Sensitivity of tropospheric loads and lifetimes of short lived pollutants to fire emissions
Atmos. Chem. Phys., 15, 3543-3563, doi:10.5194/acp-15-3543-2015, 2015
Influence of oil and gas field operations on spatial and temporal distributions of atmospheric non-methane hydrocarbons and their effect on ozone formation in winter
Summary: Emissions from oil and natural gas development in the Upper Green River basin of Wyoming are known to drive wintertime ozone production. Fugitive emissions of natural gas and condensate provide sufficient non-methane hydrocarbons (NMHC) to promote episodic ozone formation. A water treatment and recycling facility was identified as a significant source of NMHC, including toluene and m+p-xylene. Emissions from this facility have a strong influence upon peak ozone measured at downwind sites.
Atmos. Chem. Phys., 15, 3527-3542, doi:10.5194/acp-15-3527-2015, 2015
The impact of temperature vertical structure on trajectory modeling of stratospheric water vapor
Summary: We investigated the impacts of vertical temperature structures on trajectory simulations of stratospheric dehydration and water vapor by using 1) MERRA temperatures on model levels; 2) GPS temperatures at finer vertical resolutions; and 3) adjusted MERRA temperatures with finer vertical structures induced by waves. We show that despite the fact that temperatures at finer vertical structures tend to dry air by 0.1-0.3ppmv, the interannual variability in different runs is essentially the same.
Atmos. Chem. Phys., 15, 3517-3526, doi:10.5194/acp-15-3517-2015, 2015
Aerosol processing and CCN formation of an intense Saharan dust plume during the EUCAARI 2008 campaign
Atmos. Chem. Phys., 15, 3497-3516, doi:10.5194/acp-15-3497-2015, 2015
Step changes in persistent organic pollutants over the Arctic and their implications
Summary: After several decades of declining persistent organic pollutants in the arctic environment due to their global use restriction, some of these toxic chemicals increased in the mid-2000s and undertook statistically significant step changes which coincided with arctic sea ice melting. Results provide statistical evidence for the releasing of toxic chemicals from their reservoirs in the Arctic due to the rapid change in the arctic environment.
Atmos. Chem. Phys., 15, 3479-3495, doi:10.5194/acp-15-3479-2015, 2015
Estimated desert-dust ice nuclei profiles from polarization lidar: methodology and case studies
Atmos. Chem. Phys., 15, 3463-3477, doi:10.5194/acp-15-3463-2015, 2015
Long-term particulate matter modeling for health effect studies in California – Part 1: Model performance on temporal and spatial variations
Summary: Air quality model simulations have been conducted for California from 2000 to 2009 with 4km spatial resolution to provide exposure data for health effect studies. Comprehensive analysis shows that predicted concentrations for many pollutants are in agreement with measurements at monitoring stations, building confidence that the fields may be useful at times and locations where measurements are not available. Data can be downloaded for free at http://faculty.engineering.ucdavis.edu/kleeman/.
Atmos. Chem. Phys., 15, 3445-3461, doi:10.5194/acp-15-3445-2015, 2015
Total sulfate vs. sulfuric acid monomer concenterations in nucleation studies
Summary: A discrepancy of 2 orders of magnitude was found between the measured sulfuric acid monomer concentration and total sulfate, when measured with independent methods (mass spectrometry and ion chromatography) with the same source of sulphuric acid vapor. The ion chromatography method produces the exact concentrations predicted by empirical equations, and the mass spectrometry method shows significantly lower values. The discrepancy is investigated thoroughly from different points of views.
Atmos. Chem. Phys., 15, 3429-3443, doi:10.5194/acp-15-3429-2015, 2015
Major contribution of neutral clusters to new particle formation at the interface between the boundary layer and the free troposphere
Atmos. Chem. Phys., 15, 3413-3428, doi:10.5194/acp-15-3413-2015, 2015
Using the chemical equilibrium partitioning space to explore factors influencing the phase distribution of compounds involved in secondary organic aerosol formation
Summary: The manuscript presents a new way to graphically illustrate some of the processes that occur when organic particles form in the atmosphere. In particular, this method makes it possible to see how factors such as the composition of the atmosphere and temperature affect these processes.
Atmos. Chem. Phys., 15, 3395-3412, doi:10.5194/acp-15-3395-2015, 2015
Hygroscopic properties of NaCl and NaNO3 mixture particles as reacted inorganic sea-salt aerosol surrogates
Summary: This work focuses on the hygroscopic behavior of NaCl-NaNO3 mixed particles as reacted sea-salt aerosol surrogates. The experimental phase diagrams for their deliquescence and efflorescence are determined, and the efflorescence process is explained. This study has high atmospheric implications, because the observed phases and chemical microstructures are expected to help in elucidating the complexity of real ambient sea salt aerosols, their hygroscopic properties, aqueous phase chemistry, etc.
Atmos. Chem. Phys., 15, 3379-3393, doi:10.5194/acp-15-3379-2015, 2015
Diel and seasonal changes of biogenic volatile organic compounds within and above an Amazonian rainforest
Atmos. Chem. Phys., 15, 3359-3378, doi:10.5194/acp-15-3359-2015, 2015
Relating hygroscopicity and optical properties to chemical composition and structure of secondary organic aerosol particles generated from the ozonolysis of α-pinene
Atmos. Chem. Phys., 15, 3339-3358, doi:10.5194/acp-15-3339-2015, 2015
Energetic particle induced intra-seasonal variability of ozone inside the Antarctic polar vortex observed in satellite data
Summary: Energetic particles from the sun produce NOx (=N+NO+NO2) in the mesosphere/lower thermosphere. The NOx can be transported downward in the stratosphere during polar winter where NOx eventually depletes O3. This entire chain is the so-called energetic particle precipitation (EPP) indirect effect. Here we show downward propagating negative stratospheric O3 anomalies during Antarctic polar winter. The O3 anomalies are caused by geomagnetic activity and show strong hints of the EPP indirect effect.
Atmos. Chem. Phys., 15, 3327-3338, doi:10.5194/acp-15-3327-2015, 2015
Dust aerosol radiative effects during summer 2012 simulated with a coupled regional aerosol–atmosphere–ocean model over the Mediterranean
Summary: This paper uses an original approach based on a coupled regional aerosol--atmosphere--ocean model to study the dust radiative effects over the Mediterranean in summer 2012. After an evaluation of the prognostic aerosol scheme, the dust aerosol daily variability is shown to improve the simulated surface radiation and temperature at the daily scale. It has also a significant impact on the summer average, thus highlighting the importance of a relevant representation of aerosols in climate models.
Atmos. Chem. Phys., 15, 3303-3326, doi:10.5194/acp-15-3303-2015, 2015
The influence of clouds on radical concentrations: observations and modelling studies of HOx during the Hill Cap Cloud Thuringia (HCCT) campaign in 2010
Atmos. Chem. Phys., 15, 3289-3301, doi:10.5194/acp-15-3289-2015, 2015
Mesoscale modelling study of the interactions between aerosols and PBL meteorology during a haze episode in China Jing–Jin–Ji and its near surrounding region – Part 2: Aerosols' radiative feedback effects
Summary: Solar radiation reaching the ground decreases about 15% in Chinese 3JNS region and by 20 to 25% in the region with the highest AOD. Aerosol cools the PBL atmosphere but warms the atmosphere above it, leading to a more stable atmosphere that causes a decrease in turbulence diffusion of about 52% and in PBL height of about 33%; this results in a positive feedback on the PM2.5 concentration within the PBL and the surface as well as the haze formation.
Atmos. Chem. Phys., 15, 3277-3287, doi:10.5194/acp-15-3277-2015, 2015
Mesoscale modeling study of the interactions between aerosols and PBL meteorology during a haze episode in Jing–Jin–Ji (China) and its nearby surrounding region – Part 1: Aerosol distributions and meteorological features
Atmos. Chem. Phys., 15, 3257-3275, doi:10.5194/acp-15-3257-2015, 2015
Spaceborne observations of the lidar ratio of marine aerosols
Atmos. Chem. Phys., 15, 3241-3255, doi:10.5194/acp-15-3241-2015, 2015
Seasonal changes in the tropospheric carbon monoxide profile over the remote Southern Hemisphere evaluated using multi-model simulations and aircraft observations
Summary: The Southern Hemisphere (SH) serves as an important test bed for evaluating our understanding of the processes that drive the composition of the clean background atmosphere. Using data from two aircraft campaigns, combined with four atmospheric chemistry models, we find a large sensitivity in the remote SH to biogenic emissions and their subsequent chemistry and transport. Future model evaluation and measurement campaigns should prioritize reducing uncertainties in these processes.
Atmos. Chem. Phys., 15, 3217-3239, doi:10.5194/acp-15-3217-2015, 2015
Aerosol physicochemical properties and implications for visibility during an intense haze episode during winter in Beijing
Atmos. Chem. Phys., 15, 3205-3215, doi:10.5194/acp-15-3205-2015, 2015
Interannual variability of isotopic composition in water vapor over western Africa and its relationship to ENSO
Atmos. Chem. Phys., 15, 3193-3204, doi:10.5194/acp-15-3193-2015, 2015
Explaining variance in black carbon's aging timescale
Summary: The timescale for particles containing black carbon to age from hydrophobic to hygroscopic strongly influences black carbon's atmospheric lifetime and climate impact. This paper identifies the minimal set of independent variables needed to explain variance in this aging timescale. This work distills the complex interactions captured by a particle-resolved aerosol model to a few input variables and is a first step toward developing physically based parameterizations of aerosol aging.
Atmos. Chem. Phys., 15, 3173-3191, doi:10.5194/acp-15-3173-2015, 2015
Sources and contributions of wood smoke during winter in London: assessing local and regional influences
Summary: Wood is a renewable fuel but its combustion for residential heating releases a number of locally acting air pollutants, most notably particulate matter known to have adverse effects on human health. This paper used chemical tracers for wood smoke to estimate the contribution that burning wood makes to concentrations of airborne particles in the atmosphere of southern England and most particularly in London.
Atmos. Chem. Phys., 15, 3149-3171, doi:10.5194/acp-15-3149-2015, 2015
Spatiotemporal variability of water vapor investigated using lidar and FTIR vertical soundings above the Zugspitze
Summary: We quantitatively analyzed the spatiotemporal variability (minutes to hours, 500m to 10km) of water vapor (IWV and profiles) in the free troposphere recorded at the Zugspitze (Germany) with lidar and solar FTIR. We found that long-range transport of heterogeneous air masses may cause relative short-term variations of the water-vapor density which exceed the impact of local convection by 1 order of magnitude. Our results could be useful for issues of model parametrization and co-location.
Atmos. Chem. Phys., 15, 3135-3148, doi:10.5194/acp-15-3135-2015, 2015
Comparison of mercury concentrations measured at several sites in the Southern Hemisphere
Summary: • Longer-term mercury measurement in the Southern Hemisphere is compared. • Mercury, in terms of monthly and annual medians and averages, is more evenly distributed than hitherto believed. • Consequently, trends observed at one or a few sites are likely to be representative of the whole hemisphere, and smaller trends can be detected in shorter time periods. • We report a change in the trend sign at Cape Point from decreasing mercury concentrations in 1996-2004 to increasing ones since 2007.
Atmos. Chem. Phys., 15, 3125-3133, doi:10.5194/acp-15-3125-2015, 2015
Dicarboxylic acids, ketocarboxylic acids, α-dicarbonyls, fatty acids and benzoic acid in PM2.5 aerosol collected during CAREBeijing-2007: an effect of traffic restriction on air quality
Summary: The objective of this study is to identify the influence of traffic emissions and regional transport to the atmosphere in Beijing during the CAREBeijing-2007 in summer. This study demonstrates that even when primary exhaust was controlled by traffic restrictions, the contribution of secondary organic species formed from photochemical processes was critical with long-range atmospheric transport of pollutants.
Atmos. Chem. Phys., 15, 3111-3123, doi:10.5194/acp-15-3111-2015, 2015
Comment on "Observation and modelling of HOx radicals in a boreal forest" by Hens et al. (2014)
Atmos. Chem. Phys., 15, 3109-3110, doi:10.5194/acp-15-3109-2015, 2015
Chemical and stable carbon isotopic composition of PM2.5 from on-road vehicle emissions in the PRD region and implications for vehicle emission control policy
Atmos. Chem. Phys., 15, 3097-3108, doi:10.5194/acp-15-3097-2015, 2015
Properties and evolution of biomass burning organic aerosol from Canadian boreal forest fires
Summary: Particulate emissions in the form of organic aerosol from boreal forest fires in Canada have been measured during an aircraft measurement campaign. Ratios of the amount of aerosol emitted relative to gas species such as CO were calculated and show high levels of variability throughout the campaign. This variability is affected by both changes in fire conditions, as fires tended to die down later in the measurement period, and by changes to the aerosol due to chemical reactions in the atmosphere.
Atmos. Chem. Phys., 15, 3077-3095, doi:10.5194/acp-15-3077-2015, 2015
Effect of oxidant concentration, exposure time, and seed particles on secondary organic aerosol chemical composition and yield
Summary: We compared the chemistry and yields of SOA generated from OH oxidation of gas-phase precursors in a flow reactor (high OH, short residence time) and environmental chambers (low OH, long residence time). We find that chemical composition of SOA produced in the flow reactor and in chambers is similar. SOA yields measured in the flow reactor are lower than in chambers. Seed particles increase the yield of SOA produced in the flow reactor and may account in part for higher SOA yields in chambers.
Atmos. Chem. Phys., 15, 3063-3075, doi:10.5194/acp-15-3063-2015, 2015
Impact of pollution controls in Beijing on atmospheric oxygenated volatile organic compounds (OVOCs) during the 2008 Olympic Games: observation and modeling implications
Atmos. Chem. Phys., 15, 3045-3062, doi:10.5194/acp-15-3045-2015, 2015