Tropospheric ozone and its precursors from the urban to the global scale from air quality to short-lived climate forcer
Summary: Ozone holds a certain fascination in atmospheric science. It is ubiquitous in the atmosphere, central to tropospheric oxidation chemistry, yet harmful to human and ecosystem health as well as being an important greenhouse gas. It is not emitted into the atmosphere but is a by-product of the very oxidation chemistry it largely initiates. This review examines current understanding of the processes regulating tropospheric ozone at global to local scales from both measurements and models.
P. S. Monks, A. T. Archibald, A. Colette, O. Cooper, M. Coyle, R. Derwent, D. Fowler, C. Granier, K. S. Law, D. S. Stevenson, O. Tarasova, V. Thouret, E. von Schneidemesser, R. Sommariva, O. Wild, and M. L. Williams Atmos. Chem. Phys. Discuss., 14, 32709-32933, 2014 AbstractDiscussion Paper (PDF, 11503 KB)Interactive Discussion (Open, 0 Comments)Manuscript under review for ACPSpecial Issue
22 Dec 2014
The diurnal variation in stratospheric ozone from the MACC reanalysis, the ERA-Interim reanalysis, WACCM and Earth observation data: characteristics and intercomparison
Summary: The manuscript describes novel findings in the diurnal variation of stratospheric ozone by means of the MACC reanalysis, the ERA-Interim reanalysis and the WACCM model. The diurnal variation in ozone has dynamical and photochemical origins which lead to substantial amplitudes especially in the polar, stratospheric regions. The unprecedented, global view on diurnal ozone variation strengthens the implication to correct diurnally sampled satellite observations used for ozone trend estimates.
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 with 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.
L. Di Liberto, R. Lehmann, I. Tritscher, F. Fierli, J. L. Mercer, M. Snels, G. Di Donfrancesco, T. Deshler, B. P. Luo, J-U. Grooß, E. Arnone, B. M. Dinelli, and F. Cairo Atmos. Chem. Phys. Discuss., 14, 32629-32665, 2014 AbstractDiscussion Paper (PDF, 4492 KB)Interactive Discussion (Open, 0 Comments)Manuscript under review for ACP
22 Dec 2014
Origin of springtime ozone enhancements in the lower troposphere over Beijing: in situ measurements and model analysis
Summary: High ozone concentrations (up to 94.7 ppbv) were frequently observed at the altitude of ~1.5-2km over Beijing during April-May 2005. Ozone due to Asian anthropogenic pollution made major contributions to the observed ozone enhancements. These enhancements typically occurred under southerly wind and warmer conditions. An earlier onset of the Asian summer monsoon would cause more ozone enhancement events in the lower troposphere over the North China Plain in late spring and early summer.
J. Huang, H. Liu, J. H. Crawford, C. Chan, D. B. Considine, Y. Zhang, X. Zheng, C. Zhao, V. Thouret, S. J. Oltmans, S. C. Liu, D. B. A. Jones, S. D. Steenrod, and M. R. Damon Atmos. Chem. Phys. Discuss., 14, 32583-32627, 2014 AbstractDiscussion Paper (PDF, 1369 KB)Interactive Discussion (Open, 0 Comments)Manuscript under review for ACP
22 Dec 2014
Ash iron mobilization in volcanic eruption plumes
Summary: Iron released from volcanic ash can perturb the biogeochemical cycles in the ocean. But knowing the fact that the emitted ash from volcano contains insoluble iron, which processes solubilise the ash iron while it is airborne? To answer this question, a numerical model is developed in this study to simulate the gas-ash-aerosol interactions within the eruption plume. Results show that the dissolution of the ash mediated by halogen acids exert the key control on ash iron mobilisation.
Turbulence vertical structure of the boundary layer during the afternoon transition
Summary: A case study of the BLLAST experiment is considered to explore the decay of turbulence that occurs in the convective boundary layer over land during the afternoon. Based on observations and on a Large Eddy Simulation, the analysis reveals two phases in the afternoon: a first quasi-stationary phase when the turbulent kinetic energy slowly decays without significant change of the turbulence structure, and a second phase of more rapid decay with a change in spectral turbulence characteristics.
C. Darbieu, F. Lohou, M. Lothon, J. Vilà-Guerau de Arellano, F. Couvreux, P. Durand, D. Pino, E. G. Patton, E. Nilsson, E. Blay-Carreras, and B. Gioli Atmos. Chem. Phys. Discuss., 14, 32491-32533, 2014 AbstractDiscussion Paper (PDF, 1022 KB)Interactive Discussion (Open, 0 Comments)Manuscript under review for ACPSpecial Issue
22 Dec 2014
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 O3 and secondary organic aerosol (SOA) within a young biomass burning smoke plume from the Williams prescribed burn in chaparral, which was sampled over California in November 2009.
M. J. Alvarado, C. R. Lonsdale, R. J. Yokelson, S. K. Akagi, H. Coe, J. S. Craven, E. V. Fischer, G. R. McMeeking, J. H. Seinfeld, T. Soni, J. W. Taylor, D. R. Weise, and C. E. Wold Atmos. Chem. Phys. Discuss., 14, 32427-32489, 2014 AbstractDiscussion Paper (PDF, 1856 KB)Supplement (67 KB)Interactive Discussion (Open, 0 Comments)Manuscript under review for ACP
21 Dec 2014
Climate extremes in multi-model simulations of stratospheric aerosol and marine cloud brightening climate engineering
Summary: Simulations conducted in the GeoMIP and IMPLICC model intercomparison studies for climate engineering by stratospheric sulfate injection and marine cloud brightening via sea salt are analysed and compared to the reference scenario RCP4.5 for 2020 - 2060. The focus is on extremes in surface temperature and precipitation. It is found that mostly the extreme changes follow the mean changes and that extremes are also in general well mitigated, except for polar regions.
V. N. Aswathy, O. Boucher, M. Quaas, U. Niemeier, H. Muri, and J. Quaas Atmos. Chem. Phys. Discuss., 14, 32393-32425, 2014 AbstractDiscussion Paper (PDF, 6231 KB)Interactive Discussion (Open, 0 Comments)Manuscript under review for ACP
21 Dec 2014
Modeling the formation and aging of secondary organic aerosols in Los Angeles during CalNex 2010
Summary: (1) Four different parameterizations for the formation and chemical evolution of secondary organic aerosol (SOA) are evaluated using a box model representing the Los Angeles Metropolitan Region during the CalNex campaign.
(2) The SOA formed only from the oxidation of VOCs is insufficient to explain the observed SOA concentrations.
(3) The amount of SOA mass formed from diesel vehicle emissions is estimated to be 16-27%.
P. L. Hayes, A. G. Carlton, K. R. Baker, R. Ahmadov, R. A. Washenfelder, S. Alvarez, B. Rappenglück, J. B. Gilman, W. C. Kuster, J. A. de Gouw, P. Zotter, A. S. H. Prévôt, S. Szidat, T. E. Kleindienst, J. H. Offenberg, and J. L. Jimenez Atmos. Chem. Phys. Discuss., 14, 32325-32391, 2014 AbstractDiscussion Paper (PDF, 2055 KB)Supplement (1075 KB)Interactive Discussion (Open, 0 Comments)Manuscript under review for ACP
20 Dec 2014
Data assimilation in atmospheric chemistry models: current status and future prospects for coupled chemistry meteorology models
Summary: Data assimilation is used in atmospheric chemistry models to improve air quality forecasts, construct re-analyses of concentrations, and perform inverse modeling. Coupled chemistry meteorology models (CCMM) are atmospheric chemistry models that simulate meteorological processes and chemical transformations jointly. We review here the current status of data assimilation in atmospheric chemistry models with a particular focus on future prospects for data assimilation in CCMM.
M. Bocquet, H. Elbern, H. Eskes, M. Hirtl, R. Žabkar, G. R. Carmichael, J. Flemming, A. Inness, M. Pagowski, J. L. Pérez Camaño, P. E. Saide, R. San Jose, M. Sofiev, J. Vira, A. Baklanov, C. Carnevale, G. Grell, and C. Seigneur Atmos. Chem. Phys. Discuss., 14, 32233-32323, 2014 AbstractDiscussion Paper (PDF, 6740 KB)Interactive Discussion (Open, 0 Comments)Manuscript under review for ACPSpecial Issue
20 Dec 2014
Using the OMI Aerosol Index and Absorption Aerosol Optical Depth to evaluate the NASA MERRA Aerosol Reanalysis
Summary: MERRAero is an aerosol reanalysis based on the GEOS-5 Earth system model that incorporates an online aerosol module and assimilation of AOD from MODIS sensors.This study assess the quality of MERRAero absorption using independent OMI observations. In addition to comparisons to OMI Absorption AOD, we have developed a radiative transfer interface to simulate the UV Aerosol Index (AI) from assimilated aerosol fields at OMI footprint. Also, we fully diagnose the model using MISR, AERONET and CALIPSO
V. Buchard, A. M. da Silva, P. R. Colarco, A. Darmenov, C. A. Randles, R. Govindaraju, O. Torres, J. Campbell, and R. Spurr Atmos. Chem. Phys. Discuss., 14, 32177-32231, 2014 AbstractDiscussion Paper (PDF, 9370 KB)Supplement (4893 KB)Interactive Discussion (Open, 0 Comments)Manuscript under review for ACP
19 Dec 2014
Volatile organic compounds over Eastern Himalaya, India: temporal variation and source characterization using Positive Matrix Factorization
C. Sarkar, A. Chatterjee, D. Majumdar, S. K. Ghosh, A. Srivastava, and S. Raha Atmos. Chem. Phys. Discuss., 14, 32133-32175, 2014 AbstractDiscussion Paper (PDF, 2852 KB)Interactive Discussion (Open, 0 Comments)Manuscript under review for ACP
19 Dec 2014
A next generation sequencing of Arctic bacteria in snow and frost flowers: 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 the whole 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 into changing the Arctic environment and thus global climate.
Seasonal variability of Saharan desert dust and ice nucleating particles over Europe
Summary: Dust is a significant aerosol on seasonal timescales. There are large differences in dust and INP concentrations between seasons. The INP concentrations have a different vertical distribution than other common parameterisations suggest. We provide a new formulation to estimate the INP particles formed on dust aerosols, for use in process studies and regional simulations over Europe. The new formulation is captures a much more realistic seasonal variability and vertical profile.
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 1012 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 130 pptv observed at 1 m above the surface, is quite well reproduced by 1-D simulations.
Investigation of post-depositional processing of nitrate in East Antarctic snow: isotopic constraints on photolytic loss, re-oxidation, and source inputs
Summary: We evaluate isotopic composition of NO3- in different environments across East Antarctica. At high snow accumulation sites, isotopic ratios are suggestive of preservation of NO3- deposition. At low accumulation sites, isotopes are sensitive to both the loss of NO3- due to photolysis and secondary formation of NO3- within the snowpack. The imprint of post-depositional alteration is not uniform with depth, however, raising the possibility that additional NO3- chemistry occurs deeper in snowpack.
Impacts of emission reductions on aerosol radiative effects
Summary: The global aerosol-climate model ECHAM-HAMMOZ is used to study the aerosol burden and forcing changes in the coming decades. We show that aerosol burdens overall can have a decreasing trend leading to reductions in the direct aerosol effect being globally 0.06-0.4 W/m2 by 2030, whereas the cloud radiative effect could decline 0.25-0.82 W/m2. We also show that the targeted emission reduction measures can be a much better choice for the climate than overall high reductions globally.
J.-P. Pietikäinen, K. Kupiainen, Z. Klimont, R. Makkonen, H. Korhonen, R. Karinkanta, A.-P. Hyvärinen, N. Karvosenoja, A. Laaksonen, H. Lihavainen, and V.-M. Kerminen Atmos. Chem. Phys. Discuss., 14, 31899-31942, 2014 AbstractDiscussion Paper (PDF, 4189 KB)Supplement (9278 KB)Interactive Discussion (Open, 0 Comments)Manuscript under review for ACPSpecial Issue
17 Dec 2014
The effects of global change upon United States air quality
R. Gonzalez-Abraham, J. Avise, S. H. Chung, B. Lamb, E. P. Salathé Jr., C. G. Nolte, D. Loughlin, A. Guenther, C. Wiedinmyer, T. Duhl, Y. Zhang, and D. G. Streets Atmos. Chem. Phys. Discuss., 14, 31843-31897, 2014 AbstractDiscussion Paper (PDF, 6695 KB)Interactive Discussion (Open, 1 Comment)Manuscript under review for ACP
17 Dec 2014
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 represents:
• The first measurements of the stratospheric δ(37Cl) of CFCs -11 and -113.
• 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.
S. J. Allin, J. C. Laube, E. Witrant, J. Kaiser, E. McKenna, P. Dennis, R. Mulvaney, E. Capron, P. Martinerie, T. Röckmann, T. Blunier, J. Schwander, P. J. Fraser, R. L. Langenfelds, and W. T. Sturges Atmos. Chem. Phys. Discuss., 14, 31813-31841, 2014 AbstractDiscussion Paper (PDF, 1149 KB)Supplement (272 KB)Interactive Discussion (Open, 0 Comments)Manuscript under review for ACP
17 Dec 2014
Spatial and temporal variation of CO over Alberta using measurements from satellite, aircrafts, 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 south Alberta exacerbates the surface CO pollution.
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 new bottom-up emission inventory for RWC was made which included the semi-volatile components. The new 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.
H. A. C. Denier van der Gon, R. Bergström, C. Fountoukis, C. Johansson, S. N. Pandis, D. Simpson, and A. Visschedijk Atmos. Chem. Phys. Discuss., 14, 31719-31765, 2014 AbstractDiscussion Paper (PDF, 4808 KB)Supplement (346 KB)Interactive Discussion (Open, 0 Comments)Manuscript under review for ACP
16 Dec 2014
Mesoscale modeling study of the interactions between aerosols and PBL meteorology during a haze episode in China Jing–Jin–Ji and its near surrounding region – Part 1: Aerosol distributions and meteorological features
Impact of planetary boundary layer turbulence on model climate and tracer transport
Summary: PBL processes are important for weather, climate, and tracer transport and concentration. In the GEOS-5 AGCM, the PBL depth is used in the calculation of turbulent mixing. This study analyzes the impact of using different PBL depth definitions in this calculation. Near surface wind speed differences modify Saharan dust on the order of 1e-4 kg m-2. CO surface concentrations are modified by up to 20 ppb over biomass burning regions. Instantaneous CO2 differences are on the order of 10 ppm.
A global model simulation for 3-D radiative transfer impact on surface hydrology over Sierra Nevada and Rocky Mountains
Summary: This paper investigates 3-D mountain effects on solar flux distributions and their impact on surface hydrology over the Western United States, specifically the Rocky Mountains and Sierra Nevada using CCSM4 (CAM4/CLM4) global model with a 0.23°×0.31° resolution for simulations over 6 years. We show that deviations of the net surface fluxes are not only affected by 3-D mountains, but also influenced by feedbacks of cloud and snow in association with the long-term simulations.
Estimating CO2 emissions from point sources: a case study of an isolated power station
Summary: A methodology to estimate CO2 emissions from an isolated power plant
is presented and illustrated for a power station in South Australia. It involves measurement of in-situ and column-averaged CO2 near the power plant, forward modelling of the observed signals (using WRF-Chem) and inverse modelling to obtain an estimate of the power plant fluxes. Better simulation is obtained for column data giving better estimates of fluxes. Our estimated emissions are within 6% of the reported values.
S. R. Utembe, N. Jones, P. J. Rayner, I. Genkova, D. W. T. Griffith, D. M. O'Brien, C. Lunney, and A. J. Clark Atmos. Chem. Phys. Discuss., 14, 31551-31601, 2014 AbstractDiscussion Paper (PDF, 4414 KB)Interactive Discussion (Open, 0 Comments)Manuscript under review for ACP
15 Dec 2014
A novel methodology using MODIS and CERES for assessing the daily radiative forcing of smoke aerosols in large scale over the Amazonia
Summary: A new methodology was developed for obtaining daily retrievals of the direct radiative forcing of aerosols (24h-DARF) at the top of the atmosphere (TOA) using satellite remote sensing. There was a very good agreement between satellite remote sensing, ground-based and radiative transfer evaluated DARF, demonstrating the robustness of the new proposed methodology for calculated radiative forcing for biomass burning aerosols.
A comprehensive investigation on afternoon–evening transition of the atmospheric boundary layer over a tropical rural site
Summary: The afternoon-evening transition (AET) in the atmospheric boundary layer has been studied in an integrated approach using 3 years of tower, sodar and wind profiler measurements. Such a long-term dataset has been used for the first time to understand the behavior of AET. It allowed us to study the seasonal variation. In contrast to common belief that the transition evolves from bottom-to-top, the present study clearly brought out the start time of transition follows top-to-bottom evolution.
Aging of secondary organic aerosol from small aromatic VOCs: changes in chemical composition, mass yield, volatility and hygroscopicity
Summary: Secondary organic aerosol (SOA) is transformed after its initial formation. We explored the effects of this chemical aging on the composition, mass yield, volatility and hygroscopicity of SOA formed from the photo-oxidation of small aromatic volatile organic compounds. Higher exposure to the hydroxyl radical resulted in different SOA composition, average carbon oxidation state and mass yield, and the vapor pressure of SOA formed under different conditions varied by as much as a factor of 30.
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 datasets 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 datasets are appropriate choices for studies of polar processing in recent winters.
Z. D. Lawrence, G. L. Manney, K. Minschwaner, M. L. Santee, and A. Lambert Atmos. Chem. Phys. Discuss., 14, 31361-31408, 2014 AbstractDiscussion Paper (PDF, 3930 KB)Interactive Discussion (Open, 0 Comments)Manuscript under review for ACP
12 Dec 2014
A chamber study of the influence of boreal BVOC emissions and sulphuric acid on nanoparticle formation rates at ambient concentrations
Summary: In this paper, we present the first direct laboratory observations of nanoparticle formation from sulphuric acid and realistic BVOC precursor vapor mixtures performed at atmospherically relevant concentration levels. We found that the formation rate was proportional to the product of sulphuric acid and biogenic VOC emission strength, and that the formation rates were consistent with a mechanism in which nucleating BVOC oxidation products are rapidly formed and activate with sulphuric acid.
M. Dal Maso, L. Liao, J. Wildt, A. Kiendler-Scharr, E. Kleist, R. Tillmann, M. Sipilä, J. Hakala, K. Lehtipalo, M. Ehn, V.-M. Kerminen, M. Kulmala, D. Worsnop, and T. Mentel Atmos. Chem. Phys. Discuss., 14, 31319-31360, 2014 AbstractDiscussion Paper (PDF, 1715 KB)Interactive Discussion (Open, 0 Comments)Manuscript under review for ACPSpecial Issue
11 Dec 2014
Atmospheric nitrogen oxides (NO and NO2) at Dome C, East Antarctica, during the OPALE campaign
Summary: Surprisingly large concentrations and flux of atmospheric nitrogen oxides were measured at Dome C, East Antarctica. It was found that the surface snow holds a significant reservoir of photochemically produced NOx and is a sink of gas phase ozone. Main drivers of NOx snow emissions were large snow nitrate concentrations, with contributions from increased UV from decreases in stratospheric ozone. Observed halogen and hydroxyl radical concentrations were too low to explain large NO2:NO ratios.
Energetic particle induced inter-annual 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.
T. Fytterer, M. G. Mlynczak, H. Nieder, K. Pérot, M. Sinnhuber, G. Stiller, and J. Urban Atmos. Chem. Phys. Discuss., 14, 31249-31279, 2014 AbstractDiscussion Paper (PDF, 2719 KB)Interactive Discussion (Open, 0 Comments)Manuscript under review for ACP
11 Dec 2014
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.
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.
J. Um, G. M. McFarquhar, Y. P. Hong, S.-S. Lee, C. H. Jung, R. P. Lawson, and Q. Mo Atmos. Chem. Phys. Discuss., 14, 31111-31167, 2014 AbstractDiscussion Paper (PDF, 10772 KB)Interactive Discussion (Open, 0 Comments)Manuscript under review for ACP
10 Dec 2014
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 campain, this paper also increases our confidence in using the outputs of the model for this purpose.
Evaluation of a regional chemistry transport model using a newly developed regional OMI NO2 retrieval
Summary: Air pollutants can be simulated using models and measured by satellites. We present an improved OMI NO2 retrieval for the Pearl River Delta region which reduces the bias between satellite and ground measurements. The satellite retrieval is used to evaluate a regional air pollution model for which it can form a useful addition to ground measurements. To conclude, we show that our retrieval reduces the bias of satellite measurements which can be very useful for air pollution studies.
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 the
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.
The oxidation capacity of the boreal forest: first simulated reactivities of O3 and NO3
D. Mogensen, R. Gierens, J. N. Crowley, P. Keronen, S. Smolander, A. Sogachev, A. C. Nölscher, L. Zhou, M. Kulmala, M. J. Tang, J. Williams, and M. Boy Atmos. Chem. Phys. Discuss., 14, 30947-31007, 2014 AbstractDiscussion Paper (PDF, 2409 KB)Interactive Discussion (Open, 0 Comments)Manuscript under review for ACPSpecial Issue
09 Dec 2014
Examining the major contributors and controlling factors of ozone production in a rural area of the Yangtze River Delta region during harvest season
X. Pan, Y. Kanaya, H. Tanimoto, S. Inomata, Z. Wang, S. Kudo, and I. Uno Atmos. Chem. Phys. Discuss., 14, 30913-30945, 2014 AbstractDiscussion Paper (PDF, 6326 KB)Interactive Discussion (Open, 0 Comments)Manuscript under review for ACP
09 Dec 2014
Solar cycle in current reanalyses: (non)linear attribution study
On the link between hygroscopicity, volatility, and oxidation state of ambient and water-soluble aerosol in the Southeastern United States
Summary: The hygroscopicity of SE US aerosol is mostly water-soluble, with a hygroscopicity that is insensitive to partial volatilization in a thermodenuder.
The most and least oxidized components of the aerosol are the most hygroscopic of organic constituents.
No clear relationship was found between organic aerosol hygroscopicity and oxygen-to-carbon ratio.
The aerosol factors covary in a way that induces the observed diurnal invariance in total organic hygroscopicity.
K. M. Cerully, A. Bougiatioti, J. R. Hite Jr., H. Guo, L. Xu, N. L. Ng, R. Weber, and A. Nenes Atmos. Chem. Phys. Discuss., 14, 30835-30877, 2014 AbstractDiscussion Paper (PDF, 2782 KB)Interactive Discussion (Open, 0 Comments)Manuscript under review for ACP
09 Dec 2014
Elemental composition and clustering of α-pinene oxidation products for different oxidation conditions
Summary: Our study shows, based on data from three Atmospheric Pressure interface Time-Of-Flight mass spectrometers measuring in parallel charged and neutral molecules and molecular clusters, how oxidised organic compounds bind to inorganic ions (e.g. bisulfate, nitrate, ammonium). This ionisation is selective for compounds with lower molar mass due to their limited amount and variety of functional groups. We also found that extremely low volatile organic compounds (ELVOCs) can be formed immediately.
A. P. Praplan, S. Schobesberger, F. Bianchi, M. P. Rissanen, M. Ehn, T. Jokinen, H. Junninen, A. Adamov, A. Amorim, J. Dommen, J. Duplissy, J. Hakala, A. Hansel, M. Heinritzi, J. Kangasluoma, J. Kirkby, M. Krapf, A. Kürten, K. Lehtipalo, F. Riccobono, L. Rondo, N. Sarnela, M. Simon, A. Tomé, J. Tröstl, P. M. Winkler, C. Williamson, P. Ye, J. Curtius, U. Baltensperger, N. M. Donahue, M. Kulmala, and D. R. Worsnop Atmos. Chem. Phys. Discuss., 14, 30799-30833, 2014 AbstractDiscussion Paper (PDF, 1388 KB)Interactive Discussion (Open, 0 Comments)Manuscript under review for ACPSpecial Issue
09 Dec 2014
The role of organic condensation on ultrafine particle growth during nucleation events
Sources of black carbon aerosols in South Asia and surrounding regions during the Integrated Campaign for Aerosols, Gases and Radiation Budget (ICARB)
Summary: This study introduces source, sector and region specific tracers in WRF-Chem to identify most important sources of black carbon aerosols in South Asia during ICARB. We find anthropogenic emissions from residential and industrial sectors were the most important sources of BC in South Asia during ICARB. Regional transport is also found to play an important role in distributing BC over this region.
Rapid transport of East Asian pollution to the deep tropics
M. J. Ashfold, J. A. Pyle, A. D. Robinson, M. S. M. Nadzir, S. M. Phang, A. A. Samah, S. Ong, H. E. Ung, L. K. Peng, S. E. Yong, and N. R. P. Harris Atmos. Chem. Phys. Discuss., 14, 30705-30726, 2014 AbstractDiscussion Paper (PDF, 1697 KB)Interactive Discussion (Open, 0 Comments)Manuscript under review for ACP
05 Dec 2014
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.
Comparison of mercury concentrations measured at several sites in the Southern Hemisphere
Summary: • Longer term mercury measurement in southern hemisphere are 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 for the whole hemisphere, and smaller trends can be detected in shorter time periods
• We report a change of the trend sign at Cape Point from decreasing mercury concentrations in 1996 - 2004 to increasing ones since 2007
F. Slemr, H. Angot, A. Dommergue, O. Magand, M. Barret, A. Weigelt, R. Ebinghaus, E.-G. Brunke, K. Pfaffhuber, G. Edwards, D. Howard, J. Powell, M. Keywood, and F. Wang Atmos. Chem. Phys. Discuss., 14, 30611-30637, 2014 AbstractDiscussion Paper (PDF, 664 KB)Interactive Discussion (Open, 2 Comments)Manuscript under review for ACP
03 Dec 2014
Comparison of secondary organic aerosol formed with an aerosol flow reactor and environmental reaction chambers: effect of oxidant concentration, exposure time and seed particles on 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.
A. T. Lambe, P. S. Chhabra, T. B. Onasch, W. H. Brune, J. F. Hunter, J. H. Kroll, M. J. Cummings, J. F. Brogan, Y. Parmar, D. R. Worsnop, C. E. Kolb, and P. Davidovits Atmos. Chem. Phys. Discuss., 14, 30575-30609, 2014 AbstractDiscussion Paper (PDF, 767 KB)Interactive Discussion (Open, 0 Comments)Manuscript under review for ACP
02 Dec 2014
Hydrogen peroxide in the marine boundary layer over the southern Atlantic during the OOMPH cruise in March 2007
H. Fischer, A. Pozzer, T. Schmitt, P. Jöckel, T. Klippel, D. Taraborrelli, and J. Lelieveld Atmos. Chem. Phys. Discuss., 14, 30547-30573, 2014 AbstractDiscussion Paper (PDF, 1308 KB)Interactive Discussion (Open, 1 Comment)Manuscript under review for ACP
02 Dec 2014
A science-based use of ensembles of opportunities for assessment and scenario study: a re-analysis of HTAP-1 ensemble
Air quality monitoring in communities of the Canadian Arctic during the high shipping season with a focus on local and marine pollution
Summary: In an effort to characterize the effect of shipping on Arctic air quality during the 2013 shipping season, air quality monitoring stations were installed in Cape Dorset and Resolute, Nunavut, Canada to measure NOx, SO2, PM2.5, O3 and BC. Results indicate that on the order of 5-25% of local cumulative exposure to these pollutants is due to ship emissions. This approach is complementary to pollution measurements at the source and has wider applications in impact of traffic on air quality.
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.
M. Lewandowski, M. Jaoui, J. H. Offenberg, J. D. Krug, and T. E. Kleindienst Atmos. Chem. Phys. Discuss., 14, 29429-29458, 2014 AbstractDiscussion Paper (PDF, 581 KB)Interactive Discussion (Open, 1 Comment)Manuscript under review for ACP
27 Nov 2014
A~characterization of thermal structure and conditions for overshooting of tropical and extratropical cyclones with GPS radio occultation
The POLARCAT Model Intercomparison Project (POLMIP): overview and evaluation with observations
Summary: Eleven 3D 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.
L. K. Emmons, S. R. Arnold, S. A. Monks, V. Huijnen, S. Tilmes, K. S. Law, J. L. Thomas, J.-C. Raut, I. Bouarar, S. Turquety, Y. Long, B. Duncan, S. Steenrod, S. Strode, J. Flemming, J. Mao, J. Langner, A. M. Thompson, D. Tarasick, E. C. Apel, D. R. Blake, R. C. Cohen, J. Dibb, G. S. Diskin, A. Fried, S. R. Hall, L. G. Huey, A. J. Weinheimer, A. Wisthaler, T. Mikoviny, J. Nowak, J. Peischl, J. M. Roberts, T. Ryerson, C. Warneke, and D. Helmig Atmos. Chem. Phys. Discuss., 14, 29331-29393, 2014 AbstractDiscussion Paper (PDF, 6117 KB)Interactive Discussion (Open, 0 Comments)Manuscript under review for ACPSpecial Issue
Evaluating BC and NOx emission inventories for the Paris region from MEGAPOLI aircraft measurements
H. Petetin, M. Beekmann, A. Colomb, H. A. C. Denier van der Gon, J.-C. Dupont, C. Honoré, V. Michoud, Y. Morille, O. Perrussel, A. Schwarzenboeck, J. Sciare, A. Wiedensohler, and Q. J. Zhang Atmos. Chem. Phys. Discuss., 14, 29237-29304, 2014 AbstractDiscussion Paper (PDF, 2711 KB)Supplement (782 KB)Interactive Discussion (Open, 1 Comment)Manuscript under review for ACPSpecial Issue
24 Nov 2014
The impact of temperature resolution on trajectory modeling of stratospheric water vapour
Summary: We investigated the impacts of temperatures of different vertical resolutions on trajectory simulations of stratospheric water vapour by comparing results using 1) MERRA temperatures on model levels; 2) GPS temperatures in finer vertical resolutions; and 3) MERRA temperatures incorporating enhanced waves in finer vertical resolutions. It shows that using GPS and MERRA-wave temperatures tend to dry air by 0.1 and 0.2-0.3 ppmv, respectively, but the interannual variability is essentially the same.
T. Wang, A. E. Dessler, M. R. Schoeberl, W. J. Randel, and J.-E. Kim Atmos. Chem. Phys. Discuss., 14, 29209-29236, 2014 AbstractDiscussion Paper (PDF, 3281 KB)Interactive Discussion (Open, 1 Comment)Manuscript under review for ACP
24 Nov 2014
Diel and seasonal changes of Biogenic Volatile Organic Compounds within and above an Amazonian rainforest site
A. M. Yañez-Serrano, A. C. Nölscher, J. Williams, S. Wolff, E. Alves, G. A. Martins, E. Bourtsoukidis, J. Brito, K. Jardine, P. Artaxo, and J. Kesselmeier Atmos. Chem. Phys. Discuss., 14, 29159-29208, 2014 AbstractDiscussion Paper (PDF, 854 KB)Interactive Discussion (Open, 0 Comments)Manuscript under review for ACP
24 Nov 2014
First and second derivative atmospheric CO2, global surface temperature and ENSO
Summary: The previously expected linear relationship between atmospheric CO2 and climate variables including temperature is showing an increasing mismatch. This paper nonetheless provides fresh and possibly definitive support for a major relationship between CO2 and climate. Granger causality analysis provides evidence that rate of change not level of CO2 primarily influences both global temperature and the El Niño–Southern Oscillation. The results may contribute to the prediction of future climate.
High-resolution atmospheric water vapor measurements with a scanning differential absorption lidar
Summary: The scanning differential absorption lidar (DIAL) of the University of Hohenheim is presented.
We show the design of the instrument and illustrate its performance with recent water vapor measurements taken in Stuttgart-Hohenheim and in the frame of HOPE. Scanning measurements reveal the 3-dimensional structures of the water vapor field.
The influence of uncertainties within the calculation of the absorption cross-section at wavelengths around 818 nm for the WV retrieval is discussed.
Profiles of second- to third-order moments of turbulent temperature fluctuations in the convective boundary layer: first measurements with Rotational Raman Lidar
Summary: The exchange of energy between the earth surface and the atmosphere is governed by turbulent processes which form the convective boundary layer (CBL) in daytime. The representation of the CBL in atmospheric models is critical, e.g., for the simulation of clouds and precipitation. We show that a new active remote sensing technique, rotational Raman lidar, characterizes the turbulent temperature fluctuations in the CBL better than previous techniques and discuss their statistics of a typical case.
Temperature profiling of the atmospheric boundary layer with rotational Raman lidar during the HD(CP)2 observational prototype experiment
Summary: Measurements and upgrades of the Rotational Raman Lidar of University of Hohenheim during the HD(CP)2 Observational Prototype Experiment are presented in this publication. This includes 25 h long time series of temperature gradients and water vapor mixing ratio. Through simulation optimum wavelengths for high and low background cases were identified and tested successful. Low elevation measurements were performed to measure temperature gradients in altitudes around 100 m above ground level.
Iodine observed in new particle formation events in the Arctic atmosphere during ACCACIA
Summary: New particle formation (NPF) is an important contributor to aerosol number concentrations in the Arctic and thus has a major role in dictating cloud properties and climate in this region. Here we present direct evidence that the oxidation of iodine in the atmosphere causes NPF in the Greenland Sea. This is important because this is a NPF mechanism that has not previously been considered in modelling studies at these latitudes.
J. D. Allan, P. I. Williams, J. Najera, J. D. Whitehead, M. J. Flynn, J. W. Taylor, D. Liu, E. Darbyshire, L. J. Carpenter, R. Chance, and G. McFiggans Atmos. Chem. Phys. Discuss., 14, 28949-28972, 2014 AbstractDiscussion Paper (PDF, 476 KB)Supplement (1236 KB)Interactive Discussion (Open, 2 Comments)Manuscript under review for ACPSpecial Issue
20 Nov 2014
Formation and chemical aging of secondary organic aerosol during the β-caryophyllene oxidation
Ice nucleation by combustion ash particles at conditions relevant to mixed-phase clouds
Summary: Combustion ash particles nucleate ice in the immersion mode at conditions relevant to mixed-phase clouds. Hence, combustion ashes could play an important role in primary ice formation in mixed-phase clouds, especially in clouds that are formed near the emission source of these aerosol particles. From this study, there is a need to quantify the atmospheric abundance of combustion ashes in order to quantitatively assess the impact of combustion ashes on mixed-phase clouds.
N. S. Umo, B. J. Murray, M. T. Baeza-Romero, J. M. Jones, A. R. Lea-Langton, T. L. Malkin, D. O'Sullivan, J. M. C. Plane, and A. Williams Atmos. Chem. Phys. Discuss., 14, 28845-28883, 2014 AbstractDiscussion Paper (PDF, 4565 KB)Interactive Discussion (Open, 2 Comments)Manuscript under review for ACP
19 Nov 2014
Long-term real-time chemical characterization of submicron aerosols at Montsec (Southern Pyrenees, 1570 m a.s.l.)
Observations and comparisons of cloud microphysical properties in spring and summertime Arctic stratocumulus 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 parameterization, which was compared with observed values of primary ice in these clouds. We found higher concentrations of ice during summer
G. Lloyd, T. W. Choularton, K. N. Bower, J. Crosier, H. Jones, J. R. Dorsey, M. W. Gallagher, P. Connolly, A. C. R. Kirchgaessner, and T. Lachlan-Cope Atmos. Chem. Phys. Discuss., 14, 28757-28807, 2014 AbstractDiscussion Paper (PDF, 7713 KB)Interactive Discussion (Open, 2 Comments)Manuscript under review for ACP
19 Nov 2014
Interactions of bromine, chlorine, and iodine photochemistry during ozone depletions in Barrow, Alaska
C. R. Thompson, P. B. Shepson, J. Liao, L. G. Huey, E. C. Apel, C. A. Cantrell, F. Flocke, J. Orlando, A. Fried, S. R. Hall, R. S. Hornbrook, D. J. Knapp, R. L. Mauldin III, D. D. Montzka, B. C. Sive, K. Ullmann, P. Weibring, and A. Weinheimer Atmos. Chem. Phys. Discuss., 14, 28685-28755, 2014 AbstractDiscussion Paper (PDF, 1913 KB)Interactive Discussion (Open, 0 Comments)Manuscript under review for ACP
19 Nov 2014
Long-term (2001–2012) fine particulate matter (PM2.5) and the impact on human health in Beijing, China
Summary: The present study uses Aerosol Optical Depth (AOD) as proxy to estimate 12 years of PM2.5 data for the Beijing central area, and calculate the yearly premature mortality by different diseases attributable to PM2.5. The estimated average total mortality due to PM2.5 is about 6,100 individuals/yr for the period 2001-2012 in the Beijing central area, and for the period 2010-2012 the per capita mortality for all ages due to PM2.5 is around 17.9 per 10,000 person-year.
Complex chemical composition of colored surface films formed from reactions of propanal in sulfuric acid at upper troposphere/lower stratosphere aerosol acidities
Summary: We have observed the formation of colored organic surface films on solutions of propanal and sulfuric acid at acidities chosen to mimic the highly acidic aerosols in the upper troposphere and lower stratosphere. The films were found to be composed of aldol condensation products and polyacetals. If such species also form coatings on atmospheric aerosols, they could impact climate by changing the chemical, optical and cloud-forming properties of aerosols.
A. L. Van Wyngarden, S. Pérez-Montaño, J. V. H. Bui, E. S. W. Li, T. E. Nelson, K. T. Ha, L. Leong, and L. T. Iraci Atmos. Chem. Phys. Discuss., 14, 28571-28608, 2014 AbstractDiscussion Paper (PDF, 4762 KB)Supplement (554 KB)Interactive Discussion (Open, 1 Comment)Manuscript under review for ACP
19 Nov 2014
Connecting the solubility and CCN activation of complex organic aerosols: a theoretical study using the Solubility Basis Set (SBS)
Summary: Atmospheric organic aerosol is complex and thus a challenge to models. We introduce a theoretical framework (the Solubility Basis Set, SBS) to represent the solubility of multi-component mixtures. Using the SBS, 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 1-10 g/L can usually be treated as completely soluble, which simplifies the treatment of organic CCN considerably
Transport of anthropogenic and biomass burning aerosols from Europe to the Arctic during spring 2008
L. Marelle, J.-C. Raut, J. L. Thomas, K. S. Law, B. Quennehen, G. Ancellet, J. Pelon, A. Schwarzenboeck, and J. D. Fast Atmos. Chem. Phys. Discuss., 14, 28333-28384, 2014 AbstractDiscussion Paper (PDF, 3734 KB)Supplement (6379 KB)Interactive Discussion (Open, 2 Comments)Manuscript under review for ACP
17 Nov 2014
Sulfur-containing particles emitted by concealed sulfide ore deposits: an unknown source of sulfur-containing particles in the atmosphere
Mesoscale modeling 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 China 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 atmospheric, which causes a decrease in about 52% of turbulence diffusion and in about 33% of the PBL height, resulting in a positive feedback on the PM2.5 concentration within the PBL and the surface as well as the haze formation.
Spatio-temporal variability of water vapor investigated by lidar and FTIR vertical soundings above Mt. Zugspitze
Summary: We quantitatively analyzed of the spatio-temporal variability (minutes to hours, 500m to 10km) of water vapor (IWV and profiles) in the free troposphere recorded at Mt. 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 one order of magnitude. Our results could be useful for model parametrization and co-location issues.
Variability of Antarctic ozone loss in the last decade (2004–2013): high resolution simulations compared to Aura MLS observations
J. Kuttippurath, S. Godin-Beekmann, F. Lefèvre, M. L. Santee, L. Froidevaux, and A. Hauchecorne Atmos. Chem. Phys. Discuss., 14, 28203-28230, 2014 AbstractDiscussion Paper (PDF, 3584 KB)Interactive Discussion (Open, 2 Comments)Manuscript under review for ACP
13 Nov 2014
Positive feedback of dust aerosol via its impact on atmospheric stability during dust storms in the Eastern Mediterranean
Summary: In this paper we report on a new mechanism whereby the radiative effect of dust aerosol on surface fluxes acts to increase the dust loading of the atmosphere via modification of boundary-layer stability, thereby acting to enhance the radiative aerosol effect. This positive feedback between dust aerosol and boundary layer stability occurred during a series of dust storms in the Eastern Mediterranean in April 2012, which were studied using a global atmospheric composition forecast system.
Atmospheric brown clouds reach the Tibetan Plateau by crossing the Himalayas
Summary: The Himalayas and the Tibetan Plateau (HTP) region 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 region 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
Uplifting of carbon monoxide from biomass burning and anthropogenic sources to the free troposphere in East Asia
Summary: 1. High CO of 300-550 ppbv are shown in aircraft MOZAIC data between 700-300 hPa over East Asia in three episodes. Correspondingly, elevated CO is observed in satellite MOPITT data at similar altitudes.
2. GEOS-Chem and FLEXPART simulations reveal distinct uplifting processes for CO from fires and anthropogenic sources in the cases.
3. Topography in East Asia affects uplifting of CO in different ways.
4. The new version 5 MOPITT data may help diagnose of vertical transport of CO.
K. Ding, J. Liu, A. Ding, Q. Liu, T. L. Zhao, J. Shi, Y. Han, H. Wang, and F. Jiang Atmos. Chem. Phys. Discuss., 14, 28019-28077, 2014 AbstractDiscussion Paper (PDF, 17703 KB)Interactive Discussion (Open, 1 Comment)Manuscript under review for ACP
12 Nov 2014
Modelling the contribution of biogenic VOCs to new particle formation in the Jülich plant atmosphere chamber
Summary: We used the MALTE-BOX model to study new particle formation events in JPAC chamber. We found: 1. Compared to kinetic sulfuric acid nucleation, nucleation involving OH oxidation products of monoterpenes showed a better agreement with the measurements; 2. The model simulation revealed evidence of wall influence during the experiments. Thus, in order to capture the observed temporal evolution of the particle number size distribution, the model needs to consider reversible gas-wall partitioning.
L. Liao, M. Dal Maso, D. Mogensen, P. Roldin, A. Rusanen, V.-M. Kerminen, T. F. Mentel, J. Wildt, E. Kleist, A. Kiendler-Scharr, R. Tillmann, M. Ehn, M. Kulmala, and M. Boy Atmos. Chem. Phys. Discuss., 14, 27973-28018, 2014 AbstractDiscussion Paper (PDF, 5974 KB)Interactive Discussion (Open, 3 Comments)Manuscript under review for ACPSpecial Issue
12 Nov 2014
Investigation into chemistry of new particle formation and growth in subtropical urban environment
F. Salimi, L. R. Crilley, S. Stevanovic, Z. Ristovski, M. Mazaheri, C. He, G. R Johnson, G. Ayoko, and L. Morawska Atmos. Chem. Phys. Discuss., 14, 27945-27971, 2014 AbstractDiscussion Paper (PDF, 4163 KB)Interactive Discussion (Open, 1 Comment)Manuscript under review for ACP
11 Nov 2014
Lidar profiling of aerosol optical properties from Paris to Lake Baikal (Siberia)
Summary: In June 2013, a ground-based mobile lidar performed the 10,000 km ride from Paris to Ulan-Ude, near Lake Baikal. Aerosols have been characterized using two intensive properties: backscatter to extinction ratio and particle depolarization ratio. The results highlights spatial variations in the aerosol mix, with more terrigenous particles over Russia than Europe. Wildfire and desert dust plumes were also observed, offering the first optical characterization of dust from the Caspian-Aral region.
The MACC-II 2007–2008 reanalysis: atmospheric dust evaluation and characterization over Northern Africa and Middle East
E. Cuevas, C. Camino, A. Benedetti, S. Basart, E. Terradellas, J. M. Baldasano, J.-J. Morcrette, B. Marticorena, P. Goloub, A. Mortier, A. Berjón, Y. Hernández, M. Gil-Ojeda, and M. Schulz Atmos. Chem. Phys. Discuss., 14, 27797-27879, 2014 AbstractDiscussion Paper (PDF, 10527 KB)Supplement (882 KB)Interactive Discussion (Open, 1 Comment)Manuscript under review for ACPSpecial Issue
11 Nov 2014
Lifted Temperature Minimum during the atmospheric evening transition
Variations in global methane sources and sinks during 1910–2010
Summary: Atmospheric CH4 increased from 900ppb to 1800ppb during the period 1900-2010 at a rate unprecedented in any observational records. We use bottom-up emissions and a chemistry-transport model to simulate CH4. The optimized global total CH4 emission, estimated from the model-observation differences, increased at fastest rate during 1940-1990. Using δ13C of CH4 measurements we attribute this emission increase to biomass burning. Total CH4 lifetime is shortened by 4% over the simulation period.
A. Ghosh, P. K. Patra, K. Ishijima, T. Umezawa, A. Ito, D. M. Etheridge, S. Sugawara, K. Kawamura, J. B. Miller, E. J. Dlugokencky, P. B. Krummel, P. J. Fraser, L. P. Steele, R. L. Langenfelds, J. W. C. White, B. Vaughn, T. Saeki, S. Aoki, and T. Nakazawa Atmos. Chem. Phys. Discuss., 14, 27619-27661, 2014 AbstractDiscussion Paper (PDF, 1876 KB)Interactive Discussion (Open, 2 Comments)Manuscript under review for ACP
05 Nov 2014
A critical evaluation of proxy methods used to estimate the acidity of atmospheric particles
Summary: We show that the ion balance and molar ratio methods are unsuitable for use as aerosol pH proxies. Our recommendation is that 1) thermodynamic equilibrium models constrained by both gas and aerosol inputs run in the forward (open) mode, and 2) the phase partitioning of ammonia provide the best predictions of aerosol pH. Given the significance of acidity for numerous chemical processes in the atmosphere, the implications of this study are important and far reaching.
C. J. Hennigan, J. Izumi, A. P. Sullivan, R. J. Weber, and A. Nenes Atmos. Chem. Phys. Discuss., 14, 27579-27618, 2014 AbstractDiscussion Paper (PDF, 8177 KB)Interactive Discussion (Open, 2 Comments)Manuscript under review for ACP
05 Nov 2014
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 testbed 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 prioritise reducing uncertainties in these processes.
J. A. Fisher, S. R. Wilson, G. Zeng, J. E. Williams, L. K. Emmons, R. L. Langenfelds, P. B. Krummel, and L. P. Steele Atmos. Chem. Phys. Discuss., 14, 27531-27578, 2014 AbstractDiscussion Paper (PDF, 1834 KB)Supplement (1031 KB)Interactive Discussion (Open, 1 Comment)Manuscript under review for ACP
03 Nov 2014
Sources and contributions of wood smoke during winter in London: assessing local and regional influences
L. R. Crilley, W. J. Bloss, J. Yin, D. C. S. Beddows, R. M. Harrison, J. D. Allan, D. E. Young, M. Flynn, P. Williams, P. Zotter, A. S. H. Prevot, M. R. Heal, J. F. Barlow, C. H. Halios, J. D. Lee, S. Szidat, and C. Mohr Atmos. Chem. Phys. Discuss., 14, 27459-27530, 2014 AbstractDiscussion Paper (PDF, 6080 KB)Supplement (1605 KB)Interactive Discussion (Open, 2 Comments)Manuscript under review for ACP
31 Oct 2014
Parametrization of convective transport in the boundary layer and its impact on the representation of 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.
F. Hourdin, M. Gueye, B. Diallo, J.-L. Dufresne, L. Menut, B. Marticoréna, G. Siour, and F. Guichard Atmos. Chem. Phys. Discuss., 14, 27425-27458, 2014 AbstractDiscussion Paper (PDF, 1622 KB)Interactive Discussion (Open, 4 Comments)Manuscript under review for ACP
31 Oct 2014
Direct measurements of near-highway emissions in a high diesel environment
Summary: By performing source-apportionment modeling, the amount of primary and secondary organic emissions was resolved from a bulk aerosol data set measured adjacent to a major highway in France. Over 70% of vehicles on this highway were diesel, and a high concentration of BC and NOx were measured. Even close to a major highway, the bulk of the aerosol mass was secondary in nature. Radiocarbon data revealed that most of the fossil organic carbon was within primary vehicular emissions.
H. L. DeWitt, S. Hellebust, B. Temime-Roussel, S. Ravier, L. Polo, V. Jacob, C. Buisson, A. Charron, M. André, A. Pasquier, J. L. Besombes, J. L. Jaffrezo, H. Wortham, and N. Marchand Atmos. Chem. Phys. Discuss., 14, 27373-27424, 2014 AbstractDiscussion Paper (PDF, 4691 KB)Supplement (1393 KB)Interactive Discussion (Open, 2 Comments)Manuscript under review for ACP
30 Oct 2014
Airborne determination of the temporo-spatial distribution of benzene, toluene, nitrogen oxides and ozone in the boundary layer across Greater London, UK
Summary: First highly spatially resolved simultaneous mixing ratios of VOCs, NOx and O3 in the atmospheric boundary layer directly above Greater London (UK) using an airborne research aircraft. Average mixing ratios measured at 360±10 m agl over outer London were always lower than over inner London indicative of strong local vehicular sources. Airborne mixing ratio comparison with LAQN air quality ground monitoring stations suggest that airborne mixing ratios were characteristic of the surface.
Atmospheric transport simulations in support of the Carbon in Arctic Reservoirs Vulnerability Experiment (CARVE)
Summary: This paper describes the atmospheric modeling that underlies the science analysis for the NASA Carbon in Arctic Reservoirs Vulnerability Experiment (CARVE). Summary statistics of the WRF meteorological model performance on a 3.3-km grid indicate good overall agreement with surface and radiosonde observations. The high quality of the WRF meteorological fields inspires confidence in their use to drive the STILT transport model for the purpose of computing surface-influences (“footprints”).
J. M. Henderson, J. Eluszkiewicz, M. E. Mountain, T. Nehrkorn, R. Y.-W. Chang, A. Karion, J. B. Miller, C. Sweeney, N. Steiner, S. C. Wofsy, and C. E. Miller Atmos. Chem. Phys. Discuss., 14, 27263-27334, 2014 AbstractDiscussion Paper (PDF, 13742 KB)Supplement (7699 KB)Interactive Discussion (Open, 1 Comment)Manuscript under review for ACP
30 Oct 2014
On the derivation of particle nucleation rates from experimental formation rates
Summary: The manuscript provides new 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 new particles. In order to transform the formation rate to a smaller size a correction needs to be applied. The magnitude of the correction factor depends on the assumptions made for the particle loss rate as a function of size. We provide a new universal method to apply this correction.
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 potentials (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.
Particle water and pH in the southeastern United States
Summary: Particle pH can affect many aerosol processes, including gas-particle partitioning, (e.g., SOA formation), and mobilization of toxic redox metals. pH is challenging to directly measure and often improperly characterized by proxies like ion balances or molar ratios of measured aerosol ionic species. We present a detailed analyses predicting pH with a thermodynamic model, verify the prediction, and testing pH sensitivity to model inputs based on data from the SOAS field campaign.
H. Guo, L. Xu, A. Bougiatioti, K. M. Cerully, S. L. Capps, J. R. Hite, A. G. Carlton, S.-H. Lee, M. H. Bergin, N. L. Ng, A. Nenes, and R. J. Weber Atmos. Chem. Phys. Discuss., 14, 27143-27193, 2014 AbstractDiscussion Paper (PDF, 10143 KB)Supplement (685 KB)Interactive Discussion (Open, 0 Comments)Manuscript under review for ACP
29 Oct 2014
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 signal 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.
Aerosol processing and CCN formation of an intense Saharan dust plume during the EUCAARI 2008 campaign
N. Bègue, P. Tulet, J. Pelon, B. Aouizerats, A. Berger, and A. Schwarzenboeck Atmos. Chem. Phys. Discuss., 14, 27039-27091, 2014 AbstractDiscussion Paper (PDF, 6801 KB)Interactive Discussion (Open, 1 Comment)Manuscript under review for ACP
28 Oct 2014
A multi-year study of lower tropospheric aerosol variability and systematic relationships from four North American regions
Summary: Variability in aerosol optical properties relevant to radiative forcing were studied on several timescales at four continental North American NOAA-ESRL sites. Light scattering and intensive properties varied most on seasonal scales while absorption variability on weekly and diurnal timescales was comparable to its seasonal variability. Large reductions in light scattering were observed at the two long-term sites (relative to late 1990’s), along with a smaller contribution by sub-1µm particles.
Polycyclic aromatic hydrocarbons, polychlorinated biphenyls, and chlorinated pesticides in background air in central Europe – investigating parameters affecting wet scavenging of polycyclic aromatic hydrocarbons
Evaluation of black carbon emission inventories using a Lagrangian dispersion model – a case study over Southern India
Summary: Emission inventories are key component of simulating past, present and future climate. In the current manuscript we have evaluated three black carbon emission inventories for emissions of India using observations made from a strategic location. Annual average simulated black carbon concentration is found to be 35% to 60% lower than observed concentration because of underestimation of emissions of southern India in the inventories.
Characterization of forest fire smoke event near Washington, DC in Summer 2013 with multi-wavelength lidar
Summary: The multi-wavelength lidar technique was applied to the study of a smoke event near Washington DC on 26-28 August 2013. Satellite observations combined with transport model predictions imply that the smoke plume originated mainly from Wyoming/Idaho forest fires. The NASA/GSFC multi-wavelength Mie-Raman lidar was used to profile the smoke particle parameters such as volume density, effective radius and real part of refractive index.
I. Veselovskii, D. N. Whiteman, M. Korenskiy, A. Suvorina, A. Kolgotin, A. Lyapustin, Y. Wang, M. Chin, H. Bian, T. L. Kucsera, D. Perez-Ramirez, and B. Holben Atmos. Chem. Phys. Discuss., 14, 26857-26902, 2014 AbstractDiscussion Paper (PDF, 10336 KB)Interactive Discussion (Open, 2 Comments)Manuscript under review for ACP
27 Oct 2014
Evaluating the effects of China's pollution control on inter-annual trends and uncertainties of atmospheric mercury emissions
Summary: China’s atmospheric Hg emissions of anthropogenic origin have been effectively restrained through the national policy of air pollution control. Expansion of technologies with high energy efficiencies and air pollutant removal rates leads to a much slower growth of Hg emissions than that of energy and economy. However, increased uncertainties of Hg emissions are quantified from 2005 to 2012, attributed to the unclear operation status or small sample size of field tests on those technologies.
Summary: We present an experimental protocol to constrain the nature of organic vapor wall deposition in Teflon chambers and develop an empirical model to predict the wall-induced deposition rate of intermediate/semi/non-volatility organic vapors in chambers.
X. Zhang, R. H. Schwantes, R. C. McVay, H Lignell, M. M. Coggon, R. C. Flagan, and J. H. Seinfeld Atmos. Chem. Phys. Discuss., 14, 26765-26802, 2014 AbstractDiscussion Paper (PDF, 4747 KB)Supplement (2049 KB)Interactive Discussion (Open, 0 Comments)Manuscript under review for ACP
24 Oct 2014
Modulation of Saharan dust export by the North African dipole
Summary: Long term - 25 years - inter-annual variability of Saharan dust export to the subtropics is correlated with variability in Harmattan wind speeds in central Sahara and with monsoon-rainfalls in the tropics and in the Sahel. This variability is modulated by the intensity of the low-high dipole like pattern we so-called North African Dipole, whose variability may be connected with global oscillations in the climate of the tropics and subtropics.
S. Rodríguez, E. Cuevas, J. M. Prospero, A. Alastuey, X. Querol, J. López-Solano, M. I. García, and S. Alonso-Pérez Atmos. Chem. Phys. Discuss., 14, 26689-26719, 2014 AbstractDiscussion Paper (PDF, 1824 KB)Supplement (3319 KB)Interactive Discussion (Open, 0 Comments)Manuscript under review for ACP
24 Oct 2014
Frequency of new particle formation events in the urban Mediterranean climate
M. Brines, M. Dall'Osto, D. C. S. Beddows, R. M. Harrison, F. Gómez-Moreno, L. Núñez, B. Artíñano, F. Costabile, G. P. Gobbi, F. Salimi, L. Morawska, C. Sioutas, and X. Querol Atmos. Chem. Phys. Discuss., 14, 26463-26494, 2014 AbstractDiscussion Paper (PDF, 3518 KB)Supplement (191 KB)Interactive Discussion (Open, 2 Comments)Manuscript under review for ACPSpecial Issue
22 Oct 2014
Primary marine aerosol emissions from the Mediterranean Sea during pre-bloom and oligotrophic conditions: correlations to seawater chlorophyll a from a mesocosm study
A. N. Schwier, C. Rose, E. Asmi, A. M. Ebling, W. M. Landing, S. Marro, M.-L. Pedrotti, A. Sallon, F. Iuculano, S. Agusti, A. Tsiola, P. Pitta, J. Louis, C. Guieu, F. Gazeau, and K. Sellegri Atmos. Chem. Phys. Discuss., 14, 26187-26230, 2014 AbstractDiscussion Paper (PDF, 1541 KB)Interactive Discussion (Open, 1 Comment)Manuscript under review for ACPSpecial Issue
20 Oct 2014
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 lookup table which is very efficient and computationally very cheap. Adopting this approach futher allows for a more accurate treatment of the necessary approximations to supersaturation evolution and ultimately leads to a more accurate calculation of peak supersaturation and thence droplet nucleation.
Absorption of aerosols above clouds from POLDER/PARASOL measurements and estimation of their Direct Radiative Effect
F. Peers, F. Waquet, C. Cornet, P. Dubuisson, F. Ducos, P. Goloub, F. Szczap, D. Tanré, and F. Thieuleux Atmos. Chem. Phys. Discuss., 14, 25533-25579, 2014 AbstractDiscussion Paper (PDF, 2762 KB)Interactive Discussion (Open, 1 Comment)Manuscript under review for ACP
09 Oct 2014
Carbonaceous aerosols on the south edge of the Tibetan Plateau: concentrations, seasonality and sources
Biomass burning influence on high latitude tropospheric ozone and reactive nitrogen in summer 2008: a multi-model analysis based on POLMIP simulations
S. R. Arnold, L. K. Emmons, S. A. Monks, K. S. Law, D. A. Ridley, S. Turquety, S. Tilmes, J. L. Thomas, I. Bouarar, J. Flemming, V. Huijnen, J. Mao, B. N. Duncan, S. Steenrod, Y. Yoshida, J. Langner, and Y. Long Atmos. Chem. Phys. Discuss., 14, 24573-24621, 2014 AbstractDiscussion Paper (PDF, 7409 KB)Supplement (404 KB)Interactive Discussion (Open, 1 Comment)Manuscript under review for ACPSpecial Issue
24 Sep 2014
Marine submicron aerosol sources, sinks and chemical fluxes
D. Ceburnis, M. Rinaldi, J. Keane-Brennan, J. Ovadnevaite, G. Martucci, L. Giulianelli, and C. D. O'Dowd Atmos. Chem. Phys. Discuss., 14, 23847-23889, 2014 AbstractDiscussion Paper (PDF, 2969 KB)Interactive Discussion (Open, 1 Comment)Manuscript under review for ACP