Thermodynamic derivation of the energy of activation for ice nucleation
Summary: This paper describes the process of transfer of water molecules between the liquid and the ice during the early stages of ice formation. Using concepts of non-reversible thermodynamics it is shown that the activation energy can be defined in terms of the bulk self-diffusivity of water and the probability of interface transfer. Application of this model into classical nucleation theory shows good agreement of measured nucleation rates with experimental results for temperatures as low as 190K.
Atmos. Chem. Phys. Discuss., 15, 18151-18179, doi:10.5194/acpd-15-18151-2015, 2015
Aerosol size distribution seasonal characteristics measured in Tiksi, Russian Arctic
Atmos. Chem. Phys. Discuss., 15, 18109-18149, doi:10.5194/acpd-15-18109-2015, 2015
Riming in winter alpine snowfall during CLACE 2014: polarimetric radar and in-situ observations
Summary: This study investigates the microphysics of winter alpine snowfall occurring in mixed-phase clouds in an inner-Alpine valley during CLACE2014. From polarimetric radar and in-situ observations, riming is shown to be an important process leading to more intense snowfall. Riming is usually associated with more intense turbulence providing supercooled liquid water. Distinct features are identified in the vertical structure of polarimetric radar variables.
Atmos. Chem. Phys. Discuss., 15, 18065-18108, doi:10.5194/acpd-15-18065-2015, 2015
Observed spatial variability of boundary-layer turbulence over flat, heterogeneous terrain
Atmos. Chem. Phys. Discuss., 15, 18011-18064, doi:10.5194/acpd-15-18011-2015, 2015
Chemical characterization of fine organic aerosol for source apportionment at Monterrey, Mexico
Summary: The identified organic compound classes demonstrated that anthropogenic sources were dominant. Gasoline- and diesel-powered vehicles are the main emission sources (CMB = 64%) of this class of organic compounds in PM2.5. Other pyrogenic sources such as coal, grass, and wood combustion as well as meat cooking operations were also identified as contributors to the fine OA. Aging of primary emissions and the SOA from biogenic volatile organic compounds due to photochemical activity and transport.
Atmos. Chem. Phys. Discuss., 15, 17967-18010, doi:10.5194/acpd-15-17967-2015, 2015
Cold smoke: smoke-induced density currents cause unexpected smoke transport near large wildfires
Atmos. Chem. Phys. Discuss., 15, 17945-17966, doi:10.5194/acpd-15-17945-2015, 2015
The contribution of oceanic halocarbons to marine and free troposphere air over the tropical West Pacific
Summary: Our results show that a convective, well-ventilated boundary layer and intense convection led to the low atmospheric mixing ratios in the boundary layer despite the high oceanic emissions in coastal areas of the South China and Sulu Seas.
Atmos. Chem. Phys. Discuss., 15, 17887-17943, doi:10.5194/acpd-15-17887-2015, 2015
Observation of isoprene hydroxynitrates in the Southeastern United States and implications for the fate of NOx
Summary: Hydroxynitrates from isoprene oxidation were quantified both in the laboratory and the field studies. The yield of hydroxynitrates 9(+4/-3)% derived from chamber experiments was applied in a zero-dimensional model to simulate the production and loss of isoprene hydroxynitrates in ambient environmental during the 2013 Southern Oxidant and Aerosol Study (SOAS). NOx was determined to be the limiting factor for the formation of isoprene hydroxynitrates during SOAS.
Atmos. Chem. Phys. Discuss., 15, 17843-17886, doi:10.5194/acpd-15-17843-2015, 2015
Hygroscopic behavior of NaCl–MgCl2 mixture particles as nascent sea-spray aerosol surrogates and observation of efflorescence during humidifying process
Summary: Pure MgCl2 particles and NaCl-MgCl2 mixed particles are systematically investigated to observe their hygroscopic behavior, derive experimental phase diagrams, and obtain chemical micro-structures. This work provides new interesting revelations regarding the efflorescence of MgCl2 hydrates during dehydration and also humidification. The observation of an aqueous phase over a wider RH range for NaCl-MgCl2 mixture particles indicates their more probable heterogeneous chemistry than NaCl particles.
Atmos. Chem. Phys. Discuss., 15, 17797-17842, doi:10.5194/acpd-15-17797-2015, 2015
Sensitivity of polar stratospheric cloud formation to changes in water vapour and temperature
Summary: Our sensitivity studies based on air parcel trajectories confirm that Polar stratospheric cloud (PSC) formation is quite sensitive to water vapour and temperature changes. Considering water vapour time series from satellite measurements we do not find a consistent, significant trend in water vapour in the lower stratosphere during the past 15 years (2000-2014). Thus, the severe denitrification observed in 2010/2011 cannot be directly related to increases in stratospheric water vapour.
Atmos. Chem. Phys. Discuss., 15, 17743-17796, doi:10.5194/acpd-15-17743-2015, 2015
Assessment of multi-decadal WRF-CMAQ simulations for understanding direct aerosol effects on radiation "brightening" in the United States
Summary: This study attempts to determine the consequences of the changes in tropospheric aerosol burden arising from substantial reductions in emissions of SO2 and NOx associated with control measures under the Clean Air Act especially on trends in solar radiation.Comparisons of model results with observations of aerosol optical depth, aerosol concentration and radiation demonstrate that the coupled WRF-CMAQ model is capable of replicating the trends well even through it tends to underestimate the AOD.
Atmos. Chem. Phys. Discuss., 15, 17711-17742, doi:10.5194/acpd-15-17711-2015, 2015
Sources, seasonality, and trends of Southeast US aerosol: an integrated analysis of surface, aircraft, and satellite observations with the GEOS-Chem chemical transport model
Atmos. Chem. Phys. Discuss., 15, 17651-17709, doi:10.5194/acpd-15-17651-2015, 2015
Biomass burning emissions of trace gases and particles in marine air at Cape Grim, Tasmania, 41° S
Summary: Biomass burning (BB) plumes have been opportunistically measured at the Cape Grim Baseline Station in Tasmania, Australia. We show the substantial impact that BB plumes have on the composition of marine air, and the significant changes that occur as the plume is diluted and interacts with other emission sources. We provide new trace gas and particle emission factors for temperate southern Australia. A major short-lived enhancement in trace gas emissions is attributed to a minor rainfall event.
Atmos. Chem. Phys. Discuss., 15, 17599-17649, doi:10.5194/acpd-15-17599-2015, 2015
Modelling marine emissions and atmospheric distributions of halocarbons and DMS: the influence of prescribed water concentration vs. prescribed emissions
Summary: Marine produced short-lived trace gases such as halocarbons and DMS significantly impact atmospheric chemistry. To assess this impact on ozone depletion and the radiative budget, it is critical that their marine emissions in atmospheric chemistry models are quantified as accurately as possible. We show that calculating emissions online with an interactive atmosphere improves the agreement with current observations and should be employed regularly in models where marine sources are important.
Atmos. Chem. Phys. Discuss., 15, 17553-17598, doi:10.5194/acpd-15-17553-2015, 2015
Effect of retreating sea ice on Arctic cloud cover in simulated recent global warming
Atmos. Chem. Phys. Discuss., 15, 17527-17552, doi:10.5194/acpd-15-17527-2015, 2015
Wet deposition of atmospheric inorganic nitrogen at five remote stations on the Tibetan Plateau
Summary: We investigated inorganic N deposition wet deposition at five stations on the Tibetan Plateau. Combining our observations with that in previous studies, the average wet deposition of NH4+-N, NO3−-N, and inorganic N on the Tibetan Plateau was estimated to be 1.17, 0.58 and 1.75 kg N ha−1 yr−1, respectively. The inorganic N deposition for the entire Tibetan Plateau in previous studies, either through model simulations or interpolations based on limited observations, has been highly overestimated.
Atmos. Chem. Phys. Discuss., 15, 17491-17526, doi:10.5194/acpd-15-17491-2015, 2015
Reactive uptake of ammonia to secondary organic aerosols: kinetics of organonitrogen formation
Atmos. Chem. Phys. Discuss., 15, 17449-17490, doi:10.5194/acpd-15-17449-2015, 2015
A process-based 222Rn flux map for Europe and its comparison to long-term observations
Summary: Detailed 222Rn flux maps are a prerequisite for the use of radon in atmospheric transport studies. We present a high-resolution 222Rn flux map for Europe, based on a parameterization of 222Rn production and transport in the soil. Spatial variations in 222Rn exhalation rates are determined by soil uranium content, water table depth and soil texture. Temporal variations are related to soil moisture variations as the diffusion in the soil depends on available air-filled pore space.
Atmos. Chem. Phys. Discuss., 15, 17397-17448, doi:10.5194/acpd-15-17397-2015, 2015
Organic peroxide and OH formation in aerosol and cloud water: laboratory evidence for this aqueous chemistry
Summary: This paper demonstrates organic peroxide formation during aqueous photooxidation of methylglyoxal using ultra high resolution Fourier Transform Ion Cyclotron Resonance electrospray ionization mass spectrometry (FTICR-MS). Then, we provide simulation results of organic peroxide/peroxyhemiacetal formation in clouds and wet aerosols and discuss organic peroxides as a source of condensed-phase OH radicals and as a contributor to aqueous secondary organic aerosol (SOA).
Atmos. Chem. Phys. Discuss., 15, 17367-17396, doi:10.5194/acpd-15-17367-2015, 2015
Hygroscopic properties and cloud condensation nuclei activation of limonene-derived organosulfates and their mixtures with ammonium sulfate
Atmos. Chem. Phys. Discuss., 15, 17317-17365, doi:10.5194/acpd-15-17317-2015, 2015
A two-dimensional volatility basis set – Part 3: Prognostic modeling and NOx dependence
Summary: NOx is formed under high-temperature conditions such as combustion. When NOx enters the atmosphere, it alters the chemistry of organic emissions and can form organonitrates. Depending on the conditions, NOx may increase or decrease resulting aerosol concentrations. We expanded the two-dimensional volatility basis set (2D-VBS) to model organonitrates and the effect on aerosol concentrations. We discuss the mathematical framework of the model and include the code in the supplemental material.
Atmos. Chem. Phys. Discuss., 15, 17283-17316, doi:10.5194/acpd-15-17283-2015, 2015
Estimating ground-level PM2.5 in Eastern China using aerosol optical depth determined from the GOCI Satellite Instrument
Summary: 1. GOCI (Geostationary Ocean Color Imager) retrieval of AOD is consistent with AERONET AOD (RMSE=0.08-0.1) 2. GOCI-derived PM2.5 is in significant agreement with in-situ observations (R=0.81, MFB = 13%) 3. Population-weighted GOCI-derived PM2.5 over eastern China for 2013 is 53.8 μg/m3, threatening the health of its 603 million residents 4. Secondary inorganics (SO42-, NO3-, NH4+) & organic matter are the most significant components of GOCI-derived PM2.5
Atmos. Chem. Phys. Discuss., 15, 17251-17281, doi:10.5194/acpd-15-17251-2015, 2015
How large-scale subsidence affects stratocumulus transitions
Summary: A large-eddy simulation model is used to show that a weakening of the large-scale subsidence, which is associated with a future warmer climate, leads to a delay of the moment of break up of stratocumulus clouds during subtropical stratocumulus transitions. To understand what causes this delay, an novel analysis method is used to distil the contributions of individual physical processes to the evolution of the stratocumulus cloud thickness.
Atmos. Chem. Phys. Discuss., 15, 17229-17250, doi:10.5194/acpd-15-17229-2015, 2015
PM2.5 water-soluble elements in the southeastern United States: automated analytical method development, spatiotemporal distributions, source apportionment, and implications for heath studies
Summary: This work presented a new method of quantifying water-soluble elements in PM2.5 aqueous extracts (N~500) with an X-ray fluorescence analyzer. The results indicate that water-soluble elements had marked spatial and temporal patterns. Four sources were resolved: brake/tire wear, biomass burning, secondary formation, and mineral dust. The findings have informed studies on aerosol oxidative potential and provided insights into the health effects of water-soluble metals, especially Cu, Fe, Mn and Zn.
Atmos. Chem. Phys. Discuss., 15, 17189-17227, doi:10.5194/acpd-15-17189-2015, 2015
Spatial and temporal variability of clouds and precipitation over Germany: multiscale simulations across the "gray zone"
Atmos. Chem. Phys. Discuss., 15, 17135-17187, doi:10.5194/acpd-15-17135-2015, 2015
Source analysis of peroxyacetyl nitrate (PAN) in Guangzhou, China: a yearlong observation study
Summary: Photochemical smog has been a major cause of air pollution in Guangzhou, one of megacities in China. This study firstly examined the source of peroxyacetyl nitrate in Guangzhou based on a yearlong data set including PAN, ozone, nitrogen oxides and non-methane hydrocarbons. The results suggest regional air mass transport of pollutants had a major impact on the PAN concentrations in Guangzhou area, which will provide useful information for more effectively managing the air quality of Guangzhou.
Atmos. Chem. Phys. Discuss., 15, 17093-17133, doi:10.5194/acpd-15-17093-2015, 2015
Effects of emission reductions on organic aerosol in the southeastern United States
Summary: Fifteen years of gas and particle measurements at eight monitoring sites comprising the Southeastern Aerosol Research and Characterization (SEARCH) network offer insights into the sources of organic aerosol in the southeastern United States. Between 1999 and 2013, mean organic aerosol concentrations declined due to decreasing particle emissions from motor vehicles and to less secondary organic aerosol with declining emissions of sulfur dioxide, nitrogen oxides, and volatile organic compounds.
Atmos. Chem. Phys. Discuss., 15, 17051-17092, doi:10.5194/acpd-15-17051-2015, 2015
Spatiotemporal variations of air pollutants (O3, NO2, SO2, CO, PM10, and VOCs) with land-use types
Summary: Major air pollutants (O3, NO2, SO2, CO, PM10, and VOCs) with long-term records from dense observation network over Korea were extensively analyzed with land-use types, classified by Korean Government, consistent with satellite observed land covers. The weekly cycles of the pollutant showed different behaviors with the types. Regardless of land-use types, ozone has an increasing trend, while the other pollutants have decreasing trends. Most areas in Korea were VOCs-limited for ozone chemistry.
Atmos. Chem. Phys. Discuss., 15, 16985-17050, doi:10.5194/acpd-15-16985-2015, 2015
Long-range transport of black carbon to the Pacific Ocean and its dependence on aging timescale
Summary: We tag BC emissions from 13 source regions around the globe in a global chemical transport model MOZART-4, and optimize the aging timescale for each source region by minimizing errors in vertical profiles of BC mass mixing ratios between simulations and HIAPER Polo-to-Pole Observations（HIPPO）. We find that the optimized aging timescale of BC varies significantly by region and season. Our simulations indicate that BC lifetime increases nearly linearly with aging timescale for all source regions.
Atmos. Chem. Phys. Discuss., 15, 16945-16983, doi:10.5194/acpd-15-16945-2015, 2015
Radiative and thermodynamic responses to aerosol extinction profiles during the pre-monsoon month over South Asia
Atmos. Chem. Phys. Discuss., 15, 16901-16943, doi:10.5194/acpd-15-16901-2015, 2015
On retrieving refractive index of dust-like particles using shape distributions of ellipsoids
Summary: Combinations of simple mathematical model shapes called ellipsoids are used in many remote sensing and modeling applications to denote dust particles. In this study we investigate how accurately various physical parameters can be retrieved by using ellipsoids. The results show that using ellipsoids can lead to wrong results, while at the same time seeming like they work well. This means that extreme care should be used when using ellipsoids for dust, and extra validation measures should be used.
Atmos. Chem. Phys. Discuss., 15, 16861-16900, doi:10.5194/acpd-15-16861-2015, 2015
On measurements of aerosol–gas composition of the atmosphere during two expeditions in 2013 along Northern Sea Route
Summary: We discuss the spatiotemporal variations in aerosol characteristics, measured along Northern Sea Route in cruises of RVs "Akademik Fedorov" and "Professor Khljustin". The variability ranges of the average aerosol parameters in separate seas and regions were: from 2.5 to 24 cm-3 for number concentration of particles; from 830 to 2970 ng·m-3 for aerosol mass concentrations; from 20 до 150 ng·m-3 for Black Carbon mass concentrations; and from 0.03 to 0.19 for aerosol optical depth (0.5 um).
Atmos. Chem. Phys. Discuss., 15, 16775-16859, doi:10.5194/acpd-15-16775-2015, 2015
Variations of surface ozone at Ieodo Ocean Research Station in the East China Sea and influence of Asian outflows
Summary: In East Asia, emissions of O3 precursors have gradually increased and O3 concentration are expected to increase in the near future. Ieodo Ocean Research Station (IORS) located in the East China Sea is a unique research tower suitable for observing continental outflows from East Asia. In this study, we present long-term measurements of O3 at IORS, describe their characteristic variations, and evaluate the continental influence on the regional background concentrations of O3.
Atmos. Chem. Phys. Discuss., 15, 16747-16774, doi:10.5194/acpd-15-16747-2015, 2015
Sea salt aerosols as a reactive surface for inorganic and organic acidic gases in the arctic troposphere
Summary: Sea salt aerosols (SSA) are dominant particles in the arctic atmosphere. Our result suggests that the hydrophilic MgCl2 coating in fresh SSA likely intrigued the heterogeneous reactions at the beginning of SSA and acidic gases in the arctic. The content of organic matter increased in the aged SSA compared with the fresh SSA, which suggest organic acids (beside inorganic acids) participate in the aging of SSA in the arctic.
Atmos. Chem. Phys. Discuss., 15, 16715-16745, doi:10.5194/acpd-15-16715-2015, 2015
Influence of the ambient humidity on the concentration of natural deposition ice nuclei
Summary: This work deals with the origin and nature of atmospheric ice nuclei (IN). An accurate determination of the atmospheric IN concentration is relevant since they induce freezing in clouds thus initiating an efficient mechanism for cloud particles to reach a precipitating size. The effect of the relative humidity at ground level on the IN concentration was analyzed and discussed.
Atmos. Chem. Phys. Discuss., 15, 16697-16714, doi:10.5194/acpd-15-16697-2015, 2015
Ozonesonde profiles from the West Pacific Warm Pool
Summary: This paper reports the results of a field campaign with ozonesondes held in Manus Island, Papua New Guinea in February 2014. Particular attention is paid to the background current correction for the ozonesondes. We show that the ozonesonde profiles compare very well with near-coincident aircraft measurements, and show no sign of the extremely low ozone concentrations (< 5 ppbv) reported by previous papers. The minimum repeatable ozone concentration just below the tropopause was 12 ppbv.
Atmos. Chem. Phys. Discuss., 15, 16655-16696, doi:10.5194/acpd-15-16655-2015, 2015
An online aerosol retrieval algorithm using OMI near-UV observations based on the optimal estimation method
Summary: The aerosol retrieval and error analysis algorithm using the OMI measurements based on the optimal estimation method was developed in this study. The aerosol retrievals were validated using the DRAGON campaign products. The estimated errors of the retrievals well represented the actual biases between retrieval and AERONET measurements. The retrievals with thier estimated uncertainties are exprected to be valuable for the relevant studies such as trace gas retrieval and data assimilations.
Atmos. Chem. Phys. Discuss., 15, 16615-16654, doi:10.5194/acpd-15-16615-2015, 2015
High ice water content at low radar reflectivity near deep convection – Part 2: Evaluation of microphysical pathways in updraft parcel simulations
Summary: An updraft parcel model with size-resolved microphysics is used to investigate microphysical pathways leading to ice water content > 2g m-3 with mass median area-equivalent diameter of 200-300micron reported at ~11km in tropical deep convection. Parcel simulations require substantial source of small crystals at temperatures > ~-10deg C growing by vapor deposition. Warm rain in weaker updrafts paradoxically leads to greater ice mass owing to reduced competition for available water vapor.
Atmos. Chem. Phys. Discuss., 15, 16551-16613, doi:10.5194/acpd-15-16551-2015, 2015
High ice water content at low radar reflectivity near deep convection – Part 1: Consistency of in situ and remote-sensing observations with stratiform rain column simulations
Summary: Airbus measurements at elevations circa 11 km within large storm systems near Cayenne, Darwin and Santiago indicate ice mass distributed over area-equivalent diameters of 100-500 µm. Profiler-observed radar reflectivity and mean Doppler velocity under similar conditions are found to be consistent with measurements and with 1D simulations of steady-state stratiform rain columns initialized with observed ice size distributions. Results motivate investigation of ice formation pathways in Part II.
Atmos. Chem. Phys. Discuss., 15, 16505-16550, doi:10.5194/acpd-15-16505-2015, 2015
Does GOSAT capture the true seasonal cycle of XCO2?
Atmos. Chem. Phys. Discuss., 15, 16461-16503, doi:10.5194/acpd-15-16461-2015, 2015
New particle-dependent parameterizations of heterogeneous freezing processes: sensitivity studies of convective clouds with an air parcel model
Atmos. Chem. Phys. Discuss., 15, 16401-16460, doi:10.5194/acpd-15-16401-2015, 2015
Trend analysis of the 20 years time series of stratospheric ozone profiles observed by the GROMOS microwave radiometer at Bern
Summary: GROMOS (GROund-based Millimeterwave Ozone Spectrometer) has provided ozone profiles for the NDACC (Network for the Detection of Atmospheric Composition Change) at Bern since 1994. We performed a trend analysis of our 20 years time series of stratospheric ozone profiles with a multilinear parametric trend estimation method. With our estimated ozone trends we are able to support the stratospheric ozone turnaround. Besides a statistically significant negative trend in the lower mesosphere.
Atmos. Chem. Phys. Discuss., 15, 16371-16400, doi:10.5194/acpd-15-16371-2015, 2015
Ice water content vertical profiles of high-level clouds: classification and impact on radiative fluxes
Summary: *) We discuss the shape of ice water content (IWC) vertical profiles in high ice clouds and its effect on radiative properties of these clouds, both in short- and in long-wave bands (SW and LW). *) We suggest a set of primitive shapes (rectangular, isosceles trapezoid, lower and upper triangle) and propose a statistical parameterization using ice water path (IWP) as a single parameter. *) We estimate and explain simulated differences in LW/SW atmospheric radiances for suggested IWC shapes.
Atmos. Chem. Phys. Discuss., 15, 16325-16369, doi:10.5194/acpd-15-16325-2015, 2015
Ice nucleating particles at a coastal marine boundary layer site: correlations with aerosol type and meteorological conditions
Atmos. Chem. Phys. Discuss., 15, 16273-16323, doi:10.5194/acpd-15-16273-2015, 2015
Organic nitrate aerosol formation via NO3 + BVOC in the Southeastern US
Summary: This paper reports atmospheric gas- and aerosol-phase field measurements from the southeastern United States in summer 2013 to demonstrate that the oxidation of biogenic volatile organic compounds by nitrate radical produces a substantial amount of secondary organic aerosol in this region. This process, driven largely by monoterpenes, results in a comparable aerosol nitrate production rate to inorganic nitrate formation by heterogeneous uptake of HNO3 onto dust particles.
Atmos. Chem. Phys. Discuss., 15, 16235-16272, doi:10.5194/acpd-15-16235-2015, 2015
Light absorption properties of laboratory generated tar ball particles
Summary: Tar balls (TBs) are a specific particle type which is abundant in the global troposphere, in particular in biomass smoke plumes. These particles belong to the family of atmospheric brown carbon (BrC) which can absorb light in the visible range of the solar spectrum. The refractive index of TBs falls closer to those of soot than to other light-absorbing species such as humic-like substances. These findings may have substantial influence on the understanding of global radiative energy fluxes.
Atmos. Chem. Phys. Discuss., 15, 16215-16234, doi:10.5194/acpd-15-16215-2015, 2015
Absorption coefficient of urban aerosol in Nanjing, west Yangtze River Delta of China
Atmos. Chem. Phys. Discuss., 15, 16175-16213, doi:10.5194/acpd-15-16175-2015, 2015
Challenges of parameterizing CCN due to changes in particle physicochemical properties: implications from observations at a suburban site in China
Atmos. Chem. Phys. Discuss., 15, 16141-16174, doi:10.5194/acpd-15-16141-2015, 2015
Impact of environmental moisture on tropical cyclone intensification
Atmos. Chem. Phys. Discuss., 15, 16111-16139, doi:10.5194/acpd-15-16111-2015, 2015
Observations of cloud microphysics and ice formation during COPE
Summary: We present microphysics observations of cumulus clouds measured over southwest England during COPE in summer 2013. Detailed sampling focused on an isolated liquid cloud that glaciated as it matured to merge with a band of cloud downwind. We demonstrate that freezing of supercooled drizzle drops not only provides a pathway to advance the onset of the Hallett-Mossop process, it also accelerates glaciation and the formation of precipitation once it has begun.
Atmos. Chem. Phys. Discuss., 15, 16049-16110, doi:10.5194/acpd-15-16049-2015, 2015
Impact of particle shape on the morphology of noctilucent clouds
Summary: - For the first time, the shape of noctilucent cloud particles is analyzed with a 3-D Lagrangian model - Three-color lidar measurements are compared directly to optical modeling of NLC simulations with non-spherical shapes - Mix of elongated and flattened cylindrical ice particles consistent with measurements - Comparison best if flattened particles form a majority, with mean axis ratio around 2.8 - NLC from cylindrical particles slightly brighter, consists of fewer but larger ice particles
Atmos. Chem. Phys. Discuss., 15, 16019-16048, doi:10.5194/acpd-15-16019-2015, 2015
Tropical, oceanic, deep convective cloud morphology as observed by CloudSat
Summary: Presented in this paper are further results from a recently developed CloudSat tropical deep convective cloud database first detailed in Igel et al (2014). Length scales of the "average" mature tropical deep convective cloud are discussed. These scales are then used to provide insight into the relationship between the upper and lower regions of the cloud. The width of cloud anvil is shown to grow proportionally slower than the width of the rest of the cloud.
Atmos. Chem. Phys. Discuss., 15, 15977-16017, doi:10.5194/acpd-15-15977-2015, 2015
LSA SAF Meteosat FRP Products: Part 2 – Evaluation and demonstration of use in the Copernicus Atmosphere Monitoring Service (CAMS)
Atmos. Chem. Phys. Discuss., 15, 15909-15976, doi:10.5194/acpd-15-15909-2015, 2015
Meteosat SEVIRI Fire Radiative Power (FRP) products from the Land Surface Analysis Satellite Applications Facility (LSA SAF) – Part 1: Algorithms, product contents and analysis
Summary: Wildfires and prescribed burns strongly influence atmospheric chemistry, composition and climate. Characterising such fires at very high temporal resolution is best achieved using thermal observations of actively burning fires made from geostationary Earth observation satellites. This paper describes and evaluates the Fire Radiative Power (FRP) products generated by the Land Surface Analysis Satellite Applications Facility (LSA SAF) from data collected by the Meteosat geostationary satellites.
Atmos. Chem. Phys. Discuss., 15, 15831-15907, doi:10.5194/acpd-15-15831-2015, 2015
16 year climatology of cirrus clouds over a tropical station in southern India using ground and space-based lidar observations
Summary: We present the longest (1998 to 2013) cirrus cloud climatology over a tropical station using a ground based lidar. A statistically significant increase is found in the altitude of sub-visible cirrus clouds. Also a systematic shift from thin to sub-visible cirrus cloud type is observed. Ground-based lidar is found to detect more number of sub-visible cirrus clouds than space-based lidar. These findings have implications to global warming and stratosphere-troposphere water vapour exchange studies.
Atmos. Chem. Phys. Discuss., 15, 15791-15830, doi:10.5194/acpd-15-15791-2015, 2015
Improving aerosol interaction with clouds and precipitation in a regional chemical weather modeling system
Summary: A comprehensive aerosol-cloud-precipitation interaction (ACI) scheme has been developed under CMA chemical weather modeling system GRAPES/CUACE. The ACI for January 2013 has been studied under this model. The interactive micro-physical properties of clouds improve the precipitation, showing 24% to 48% enhancements of TS scoring for 6-h precipitation in all regions and reduction of the regional mean bias of temperature by 3 °C in certain precipitation events.
Atmos. Chem. Phys. Discuss., 15, 15755-15790, doi:10.5194/acpd-15-15755-2015, 2015
Post bubble-closeoff fractionation of gases in polar firn and ice cores: effects of accumulation rate on permeation through overloading pressure
Atmos. Chem. Phys. Discuss., 15, 15711-15753, doi:10.5194/acpd-15-15711-2015, 2015
The regional distribution characteristics of aerosol optical depth over the Tibetan Plateau
Summary: Different monthly variation patterns of aerosol optical depth are observed over the southern and northern Tibetan Plateau (TP). A natural boundary seems to extend to an altitude of 6–8 km, acting as a dividing line of higher dust occurrence in the northern TP and lower dust occurrence in the southern TP. The seasonal variations and spatial distribution patterns are closely related to high altitude terrain and atmospheric circulation.
Atmos. Chem. Phys. Discuss., 15, 15683-15710, doi:10.5194/acpd-15-15683-2015, 2015
Natural new particle formation at the coastal Antarctic site Neumayer
Summary: We measured condensation particle (CP) concentrations and particle size distributions at the coastal Antarctic station Neumayer. Several nucleation events were observed, but particles did not grow up to sizes required for acting as cloud condensation nuclei. A simple estimation indicated that apart from sulfuric acid, the derived growth rates required other low volatile precursor vapours.
Atmos. Chem. Phys. Discuss., 15, 15655-15681, doi:10.5194/acpd-15-15655-2015, 2015
Black carbon concentrations and mixing state in the Finnish Arctic
Summary: We have measured atmospheric aerosol composition by using a Single Particle Soot Photometer (SP2) in the Finnish Arctic during winter 2011-2012. SP2 can give detailed information about mass distributions and mixing state of refractory black carbon (rBC). The measurements showed varying rBC mass concentrations, but relatively constant rBC core size distributions and mixing state parameters. On the average, 24% of all particles contain rBC and the observed rBC cores are always thickly coated.
Atmos. Chem. Phys. Discuss., 15, 15621-15654, doi:10.5194/acpd-15-15621-2015, 2015
Consistent response of Indian summer monsoon to Middle East dust in observations and simulations
Summary: Satellite data shows that the ISM rainfall in coastal southwest India, central and northern India, and Pakistan are closely associated with Middle East dust aerosols. Numerical modeling shows that the increased ISM rainfall is related to the enhanced southwesterly flow and moisture transport from the Arabian Sea to the Indian subcontinent, which are associated with the development of an anomalous low pressure system over the Arabian Sea due to dust-induced atmospheric heating.
Atmos. Chem. Phys. Discuss., 15, 15571-15619, doi:10.5194/acpd-15-15571-2015, 2015
Motion-correlated flow distortion and wave-induced biases in air–sea flux measurements from ships
Summary: Signals at scales associated with wave and platform motion are often apparent in ship-based turbulent flux measurements, but it has been uncertain whether this is due to measurement error or to wind-wave interactions. We show that the signal has a dependence on horizontal ship velocity, and that removing the signal reduces the dependence of the momentum flux on the orientation of the ship to the wind. We conclude that the signal is a bias due to time-varying motion-dependent flow distortion.
Atmos. Chem. Phys. Discuss., 15, 15543-15570, doi:10.5194/acpd-15-15543-2015, 2015
Relating the hygroscopic properties of submicron aerosol to both gas- and particle-phase chemical composition in a boreal forest environment
Atmos. Chem. Phys. Discuss., 15, 15511-15541, doi:10.5194/acpd-15-15511-2015, 2015
Chemical and physical influences on aerosol activation in liquid clouds: an empirical study based on observations from the Jungfraujoch, Switzerland
Atmos. Chem. Phys. Discuss., 15, 15469-15510, doi:10.5194/acpd-15-15469-2015, 2015
Stable carbon isotope ratios of ambient secondary organic aerosols in Toronto
Atmos. Chem. Phys. Discuss., 15, 15431-15467, doi:10.5194/acpd-15-15431-2015, 2015
Annual evapotranspiration retrieved solely from satellites' vegetation indices for the Eastern Mediterranean
Atmos. Chem. Phys. Discuss., 15, 15397-15429, doi:10.5194/acpd-15-15397-2015, 2015
Black carbon, particle number concentration and nitrogen oxide emission factors of random in-use vehicles measured with the on-road chasing method
Atmos. Chem. Phys. Discuss., 15, 15355-15396, doi:10.5194/acpd-15-15355-2015, 2015
Spatial and temporal variations of the concentrations of PM10, PM2.5 and PM1 in China
Summary: Concentrations of PM10, PM2.5 and PM1 were monitored at 24 stations of CAWNET from 2006 to 2014. The average level of PM concentrations and relationships were investigated. Seasonal, interannual, diurnal variations of the PM were revealed. The meteorological factors effects on the PM were discussed. The highest particulate matter (PM) concentrations were observed at the stations of Xian, Zhengzhou and Gucheng, in Guanzhong and the Hua Bei Plain (HBP).
Atmos. Chem. Phys. Discuss., 15, 15319-15354, doi:10.5194/acpd-15-15319-2015, 2015
Neutral atmosphere temperature change at 90 km, 70° N, 19° E, 2003–2014
Atmos. Chem. Phys. Discuss., 15, 15289-15317, doi:10.5194/acpd-15-15289-2015, 2015
Investigation of particle and vapor wall-loss effects on controlled wood-smoke smog-chamber experiments
Summary: Losses of semi-volatile vapors to Teflon walls may contribute to significant primary particle evaporation during wood-smoke aerosol experiments. These vapor losses may also affect secondary organic aerosol formation during these experiments.
Atmos. Chem. Phys. Discuss., 15, 15243-15288, doi:10.5194/acpd-15-15243-2015, 2015
Evaluating the climate and air quality impacts of short-lived pollutants
Summary: This paper presents a summary of the findings of the ECLIPSE EU project. The project has investigated the climate and air quality impacts of short-lived climate pollutants (especially methane, ozone, aerosols) and has designed a global mitigation strategy that maximizes co-benefits between air quality and climate policy. Transient climate model simulations allowed quantifying the impacts on temperature (e.g., reduction in global warming by 0.22 K for the decade 2041-2050) and precipitation.
Atmos. Chem. Phys. Discuss., 15, 15155-15241, doi:10.5194/acpd-15-15155-2015, 2015
Tropical response to extratropical eastward propagating waves
Summary: Eastward propagating 18-day waves of zonal wavenumbers (k=1-5) are observed in mid-latitude meridional winds at 200 hPa during December 2012-February 2013. Among these, the 18-day wave of k=5 propagates equatorward. Presence of wave of similar periodicity (18-day) and zonal structure (k=5) in tropical OLR as that of extratropical wave disturbance is first reported. We suggest that the selective response of the tropical wave forcing is due to the lateral forcing of the extra-tropical wave.
Atmos. Chem. Phys. Discuss., 15, 15137-15153, doi:10.5194/acpd-15-15137-2015, 2015
Transport pathways of peroxyacetyl nitrate in the upper troposphere and lower stratosphere from different monsoon systems during the summer monsoon season
Atmos. Chem. Phys. Discuss., 15, 15087-15135, doi:10.5194/acpd-15-15087-2015, 2015
A synthesis of cloud condensation nuclei counter (CCNC) measurements within the EUCAARI network
Summary: The research paper presents the first comprehensive overview of field measurements with the CCN Counter performed at a large number of locations around the world within the EUCAARI framework. The paper sheds light on the CCN number concentrations and activated fractions around the world and their dependence on the water vapour supersaturation ratio, the dependence of aerosol hygroscopicity on particle size, and seasonal and diurnal variation of CCN activation and hygroscopic properties.
Atmos. Chem. Phys. Discuss., 15, 15039-15086, doi:10.5194/acpd-15-15039-2015, 2015
Modeling study on the transport of summer dust and anthropogenic aerosols over the Tibetan Plateau
Summary: We firstly evaluated the Spectral Radiation-Transport Model for Aerosol Species combined with a non-hydrostatic regional model through comparing the simulation results and satellite observations, both in horizontal and vertical. The dust and anthropogenic aerosols in summer over the Tibetan Plateau are evaluated, and their distributions over the TP are presented. The transport of these aerosols over the Tibetan Plateau is also explored via combining the simulation results and reanalysis data.
Atmos. Chem. Phys. Discuss., 15, 15005-15037, doi:10.5194/acpd-15-15005-2015, 2015
Emissions of nitrogen oxides from US urban areas: estimation from Ozone Monitoring Instrument retrievals for 2005–2014
Summary: Using an exponentially-modified Gaussian method and taking into account the effect of wind on NO2 distributions, we estimate three-year moving-average emissions of summertime NOx from 35 U.S. urban areas directly from NO2 retrievals of the OMI during 2005−2014. Total OMI-derived NOx emissions over U.S. urban areas decreased by 49%, consistent with reductions of 43%, 49%, and 44% in the bottom-up NOx emissions, the weak-wind OMI NO2 burdens, and the averaged NO2 concentrations, respectively.
Atmos. Chem. Phys. Discuss., 15, 14961-15003, doi:10.5194/acpd-15-14961-2015, 2015
A comparison of secondary organic aerosol (SOA) yields and composition from ozonolysis of monoterpenes at varying concentrations of NO2
Summary: The addition of NO2 to atmospheric particle formation simulations based on ozone reactions with tree-emitted monoterpenes results in changing particle composition and mass yields, with effects that vary across the range of studied monoterpenes. For alpha-pinene, a dominantly emitted terpene in the United States, NO2 addition suppresses particle formation, while for others, particle yields remain high.
Atmos. Chem. Phys. Discuss., 15, 14923-14960, doi:10.5194/acpd-15-14923-2015, 2015
Evaluation of regional background particulate matter concentration based on vertical distribution characteristics
Summary: It is crucial for studying regional-scale PM pollution and for the development of efficient joint control policy to improve understanding of the regional background PM concentration. Based on the spectrum analysis of vertical variation of the atmospheric boundary layer structure and particle mass concentration, as well as the vertical distribution of particle size, chemical composition and pollution source apportionment, a method to estimate regional background PM concentration is proposed.
Atmos. Chem. Phys. Discuss., 15, 14889-14921, doi:10.5194/acpd-15-14889-2015, 2015
The importance of Asia as a source of black carbon to the European Arctic during springtime 2013
Summary: We show that during the springtime of 2013, the anthropogenic pollution particularly from sources in Asia, contributed significantly to black carbon across the European Arctic free troposphere. In contrast to previous studies, the contribution from open wildfires was minimal. Given that Asian pollution is likely to continue to rise over the coming years, it is likely that the radiative forcing in the Arctic will also continue to increase.
Atmos. Chem. Phys. Discuss., 15, 14843-14887, doi:10.5194/acpd-15-14843-2015, 2015
Global HCFC-22 measurements with MIPAS: retrieval, validation, climatologies and trends
Summary: HCFC-22 global distributions from MIPAS measurements for 2005 to 2012 are presented. Tropospheric trends are in good agreement with ground-based observations. A layer of enhanced HCFC-22 in the upper tropospheric tropics and Northern subtropics is identified to come from Asian sources uplifted in the Asian monsoon. Stratospheric distributions provide show seasonal, semi-annual, and QBO-related variations. Hemispheric asymmetries of trends hint towards a change in the stratospheric circulation.
Atmos. Chem. Phys. Discuss., 15, 14783-14841, doi:10.5194/acpd-15-14783-2015, 2015
Advanced source apportionment of size-resolved trace elements at multiple sites in London during winter
Summary: Trace element measurements in three particle size ranges (PM10-2.5, PM2.5-1.0 and PM1.0-0.3) were performed with 2h time resolution at kerbside, urban background and rural sites during the ClearfLo winter 2012 campaign in London. The environment-dependent variability of emissions was characterized using the Multilinear Engine implementation of the Positive Matrix Factorization model. A total of nine different factors was resolved from local, regional and natural origin.
Atmos. Chem. Phys. Discuss., 15, 14733-14781, doi:10.5194/acpd-15-14733-2015, 2015
Reassessment of MIPAS age of air trends and variability
Summary: Stratospheric circulation is thought to change as a consequence of climate change. Empirical evidence, however, is sparse. In this paper we present latitude- and altitude-resolved trends of the mean age of stratospheric air as derived from SF6 measurements performed by the MIPAS satellite instrument. The mean of the age of stratospheric air is a measure of the intensity of the Brewer-Dobson circulation. In this paper we discuss differences with respect to a preceding analysis by Stiller et al.
Atmos. Chem. Phys. Discuss., 15, 14685-14732, doi:10.5194/acpd-15-14685-2015, 2015
Oceanic bromine emissions weighted by their ozone depletion potential
Atmos. Chem. Phys. Discuss., 15, 14643-14684, doi:10.5194/acpd-15-14643-2015, 2015
Sources of long-lived atmospheric VOCs at the rural boreal forest site, SMEAR II
Summary: In this study main source areas for long-lived VOCs at the boreal forest in SMEAR II were determined. Air masses arriving from eastern and western directions were more polluted than those arriving from northern direction. Biogenic and anthropogenic influence of in three different source profiles were determined. The elevated trace gas concentrations from forest fire episodes were observed clearly in the trajectory analysis.
Atmos. Chem. Phys. Discuss., 15, 14593-14641, doi:10.5194/acpd-15-14593-2015, 2015
Long-term real-time measurements of aerosol particle composition in Beijing, China: seasonal variations, meteorological effects, and source analysis
Summary: We conducted the first long-term real-time measurement of submicron aerosol composition in Beijing using an ACSM for 1 year. The seasonal variations of mass concentrations and chemical composition of submicron aerosol were investigated in detail, and the meteorological effects particularly temperature and relative humidity on aerosol chemistry were elucidated. Finally, the potential source areas of aerosol species during four seasons were identified.
Atmos. Chem. Phys. Discuss., 15, 14549-14591, doi:10.5194/acpd-15-14549-2015, 2015
Decadal trends in global CO emissions as seen by MOPITT
Summary: We studied the global CO concentration decline over the recent decade with a sophisticated atmospheric inversion system assimilating MOPITT CO retrievals, surface methane and surface methyl-chloroform in-situ measurements. The inversion interprets the CO concentration decline as a 17% decrease in the CO emissions from 2002 to 2011, twice the negative trend estimated by emission inventories. In contrast to bottom-up inventories, we find negative trends in China and positive trends in Africa.
Atmos. Chem. Phys. Discuss., 15, 14505-14547, doi:10.5194/acpd-15-14505-2015, 2015
NO2 seasonal evolution in the North Subtropical free troposphere
Summary: The NO2 seasonal evolution in the free troposphere (FT) has been established for first time based on remote sensing technique (MAXDOAS) thus avoiding the problems of local pollution of in situ instruments. A clear seasonality has been found with background levels of 20-40pptv. Evidence has been found on fast direct injection of surface air into the free troposphere. This result might have implications on the FT distribution of halogens and other species with marine sources.
Atmos. Chem. Phys. Discuss., 15, 14473-14504, doi:10.5194/acpd-15-14473-2015, 2015
Simultaneous monitoring of stable oxygen isotope composition in water vapour and precipitation over the central Tibetan Plateau
Atmos. Chem. Phys. Discuss., 15, 14445-14472, doi:10.5194/acpd-15-14445-2015, 2015
Organic aerosol evolution and transport observed at Mt. Cimone (2165 m a.s.l.), Italy, during the PEGASOS campaign
Summary: This work highlights the important contribution of organic aerosols to the composition of submicron particles at remote mountain sites. Moreover, it confirms the importance of regional scale physical and chemical processes and of transboundary transport in determining the background aerosol composition at rural European sites.
Atmos. Chem. Phys. Discuss., 15, 14403-14443, doi:10.5194/acpd-15-14403-2015, 2015
Acetylene (C2H2) and hydrogen cyanide (HCN) from IASI satellite observations: global distributions, validation, and comparison with model
Summary: We present global distributions of acetylene (C2H2) and hydrogen cyanide (HCN) total columns derived from the Infrared Atmospheric Sounding Interferometer (IASI). C2H2 and HCN are ubiquitous atmospheric trace gases with medium tropospheric lifetime, which are frequently used as indicators of combustion sources and as tracers for atmospheric transport and chemistry. We show that there is an overall agreement between ground-based and space measurements, as well as model simulations.
Atmos. Chem. Phys. Discuss., 15, 14357-14401, doi:10.5194/acpd-15-14357-2015, 2015
The impact of embedded valleys on daytime pollution transport over a mountain range
Atmos. Chem. Phys. Discuss., 15, 14315-14356, doi:10.5194/acpd-15-14315-2015, 2015
The impact of volcanic aerosols on stratospheric ozone and the Northern Hemisphere polar vortex: separating radiative from chemical effects under different climate conditions
Summary: After volcanic eruptions different radiative and chemical processes take place in the stratosphere which perturb the ozone layer and cause pronounced dynamical changes. In idealized chemistry-climate model simulations the importance of these processes and the modulating role of the climate state is analysed. The chemical effect strongly differs between a preindustrial and present day climate, but the effect on the dynamics is weak. Radiative processes dominate the dynamics in all climate states.
Atmos. Chem. Phys. Discuss., 15, 14275-14314, doi:10.5194/acpd-15-14275-2015, 2015
On the potential of ICOS atmospheric CO2 measurement network for the estimation of the biogenic CO2 budget of Europe
Summary: We study the potential of the European Integrated Carbon Observing System (ICOS) atmospheric network for estimating European CO2 ecosystem fluxes. Regional atmospheric inversions with synthetic data are used to derive it in terms of statistical uncertainty. This potential is high in Western Europe and future extensions of the network will increase it in Eastern Europe. Future improvements of the models underlying the inversion should also significantly decrease uncertainties at high resolution.
Atmos. Chem. Phys. Discuss., 15, 14221-14273, doi:10.5194/acpd-15-14221-2015, 2015
Impact of vehicular emissions on the formation of fine particles in the Sao Paulo Metropolitan Area: a numerical study with the WRF-Chem model
Summary: This study provides a first step to understand the impact of vehicular emissions on the formation of secondary particles as well as the feedback between these particles and meteorology in the Sao Paulo Metropolitan Area (SPMA). Among the main research findings are: - The emissions of primary gases from vehicles led to a production between 20 and 30% due to new particles formation in relation to the total mass concentration PM2.5 in the downtown SPMA.
Atmos. Chem. Phys. Discuss., 15, 14171-14219, doi:10.5194/acpd-15-14171-2015, 2015
Black carbon aerosol in winter northeastern Qinghai-Tibetan Plateau, China: the effects from South Asia pollution
Summary: An intensive measurement campaign was conducted at the Qinghai-Tibetan Plateau using a ground-based single particle soot photometer (SP2) and a photoacoustic extinctiometer (PAX). Significant enhancements of BC loadings and number fraction of coated BC were observed during pollution episode. Backward trajectory, fire counts map and potential source contribution function model studies suggest that the biomass burning air masses from North India contributed to the increased BC loadings.
Atmos. Chem. Phys. Discuss., 15, 14141-14169, doi:10.5194/acpd-15-14141-2015, 2015
Impacts of historical climate and land cover changes on tropospheric ozone air quality and public health in East Asia over 1980–2010
Summary: Historical land cover and land use change alone over 1980-2010 could lead to reduced summertime surface ozone by up to 4ppbv in East Asia. Climate change alone could lead to an increase in summertime ozone by 2-10ppbv in most of East Asia. Land cover change could offset part of the climate effect and lead to a previously unknown public health benefit. The sensitivity of surface ozone to land cover change is more dependent on dry deposition than isoprene emission in most of East Asia.
Atmos. Chem. Phys. Discuss., 15, 14111-14139, doi:10.5194/acpd-15-14111-2015, 2015
Investigating the observed sensitivities of air quality extremes to meteorological drivers via quantile regression
Atmos. Chem. Phys. Discuss., 15, 14075-14109, doi:10.5194/acpd-15-14075-2015, 2015
Can a coupled meteorology-chemistry model reproduce the historical trend in aerosol direct radiative effects over the Northern Hemisphere?
Summary: The ability of a coupled meteorology-chemistry model (WRF-CMAQ) in reproducing the historical trend in AOD and clear-sky SWR over the N-Hemisphere has been evaluated through a comparison of 21-year simulated results with observation-derived records from 1990-2010. Questions of How well does the model represent the regional and temporal variability of aerosol burden and DRE, and Is the model able to capture past trends in aerosol loading and associated radiatiation effects will be addressed.
Atmos. Chem. Phys. Discuss., 15, 14027-14073, doi:10.5194/acpd-15-14027-2015, 2015
A study of the impact of synoptic weather conditions and water vapor on aerosol-cloud relationships over major urban clusters of China
Summary: The impact of aerosols on cloud cover (CC) under the influence of water vapor is studied using a decade of satellite observations. Water vapor is found to have a stronger impact on CC than aerosols. The water vapour impact shows that the hydrological cycle interferes with the aerosol climatic impact and we need to improve our understanding of this interference.
Atmos. Chem. Phys. Discuss., 15, 14007-14026, doi:10.5194/acpd-15-14007-2015, 2015
Thermodynamics of the formation of sulfuric acid dimers in the binary (H2SO4-H2O) and ternary (H2SO4-H2O-NH3) system
Summary: New particle formation (NPF) is an important atmospheric process. At cold temperatures in the upper troposphere the binary (H2SO4-H2O) and ternary (H2SO4-H2O-NH3) system are thought to be important for NPF. Sulfuric acid monomer (H2SO4) and sulfuric acid dimer ((H2SO4)2) concentrations were measured between 208 and 248K for these systems and dimer evaporation rates were derived. These data will help to better understand and predict binary and ternary nucleation at low temperatures.
Atmos. Chem. Phys. Discuss., 15, 13957-14006, doi:10.5194/acpd-15-13957-2015, 2015
A better understanding of hydroxyl radical photochemical sources in cloud waters collected at the puy de Dôme station: experimental vs. modeled formation rates
Atmos. Chem. Phys. Discuss., 15, 13923-13955, doi:10.5194/acpd-15-13923-2015, 2015
Impact of 2050 climate change on North American wildfire: consequences for ozone air quality
Summary: Based on simulated meteorology from 13 GCMs, we projected future wildfire activity in Alaskan and Canadian ecoregions by the midcentury. The most robust change is the increases of 150-390% in area burned over Alaska and western Canada. The models also predict increases of 45-90% in the central and southern Canadian ecoregions, but a decrease of up to 50% in northern Canada. We further quantify how the changes in wildfire emissions may affect ozone concentrations in North America.
Atmos. Chem. Phys. Discuss., 15, 13867-13921, doi:10.5194/acpd-15-13867-2015, 2015
Influence of mineral dust and sea spray supermicron particle concentrations and acidity on inorganic NO3− aerosol during the 2013 Southern Oxidant and Aerosol Study
Summary: We report ion chromatographic measurements of gas- and aerosol-phase inorganic species at the SOAS 2013 field study. Our particular focus is on inorganic nitrate aerosol formation via HNO3 uptake onto coarse-mode dust and sea-salt particles, which we find to be the dominant source of episodic inorganic nitrate at this site, due to the high acidity of the particles preventing formation of NH4NO3. We calculate a production rate of inorganic nitrate aerosol.
Atmos. Chem. Phys. Discuss., 15, 13827-13865, doi:10.5194/acpd-15-13827-2015, 2015
An empirically derived inorganic sea spray source function incorporating sea surface temperature
Summary: We have developed an inorganic sea spray source function that is based upon state-of-the-art measurements of sea spray aerosol production using a temperature-controlled plunging jet sea spray aerosol chamber. The sea spray sea spray source function was implemented in a Lagrangian particle dispersion model and showed good skill in predicting measurements of Na+ concentration at a number of field sites, underlining its validity.
Atmos. Chem. Phys. Discuss., 15, 13783-13826, doi:10.5194/acpd-15-13783-2015, 2015
Historic records of organic aerosols from a high Alpine glacier: implications of biomass burning, anthropogenic emissions, and dust transport
Summary: The paper focuses on the determination and interpretation of historic records of organic aerosol constituents in an ice core from Grenzgletscher in the southern Swiss Alps, covering the time period from 1942 to 1993. The resulting long-term records of aerosol compounds were found to be influenced by the forest fire history in southern Switzerland, anthropogenic emissions, as well as changing mineral dust transport to the drilling site.
Atmos. Chem. Phys. Discuss., 15, 13747-13781, doi:10.5194/acpd-15-13747-2015, 2015
The ENSO signal in atmospheric composition fields: emission driven vs. dynamically induced changes
Atmos. Chem. Phys. Discuss., 15, 13705-13745, doi:10.5194/acpd-15-13705-2015, 2015
Atmospheric nitrogen deposition to the northwestern Pacific: seasonal variation and source attribution
Summary: Rapid Asian industrialization has led to increased atmospheric nitrogen deposition downwind. This work analyzes the sources and processes controlling atmospheric nitrogen deposition to the northwestern Pacific. Both nitrogen emissions and meteorology largely controlled by the East Asian Monsoon determine the seasonality of nitrogen deposition. Ascribing deposition over the marginal seas to nitrogen sources from different regions and sectors shows important contribution from fertilizer use.
Atmos. Chem. Phys. Discuss., 15, 13657-13703, doi:10.5194/acpd-15-13657-2015, 2015
Remote sensing of soot carbon – Part 1: Distinguishing different absorbing aerosol species
Atmos. Chem. Phys. Discuss., 15, 13607-13656, doi:10.5194/acpd-15-13607-2015, 2015
A global aerosol classification algorithm incorporating multiple satellite data sets of aerosol and trace gas abundances
Atmos. Chem. Phys. Discuss., 15, 13551-13605, doi:10.5194/acpd-15-13551-2015, 2015
Chemical characterization of submicron aerosol and particle growth events at a national background site (3295 m a.s.l.) in the Tibetan Plateau
Summary: An autumn field campaign was conducted at a national background site (3295m a.s.l.) in the Tibetan Plateau. The submicron aerosol was dominated by organics (43%) and sulfate (28%). Secondary organic aerosol (SOA) dominated OA (85%) with 17% being aged biomass burning OA. New particle formation and growth events were frequently observed with an average particle growth rate of 2.0nm hr-1. The important role of organics in particle growth in the Tibetan Plateau was also demonstrated.
Atmos. Chem. Phys. Discuss., 15, 13515-13550, doi:10.5194/acpd-15-13515-2015, 2015
Modelled and observed changes in aerosols and surface solar radiation over Europe between 1960 and 2009
Summary: We evaluate a coupled chemistry climate model over Europe for the period 1960-2009 against observations of aerosol mass, aerosol optical depth (AOD) and surface solar radiation (SSR). The model underestimates aerosol mass but is less biased when compared to AOD and SSR. Observed trends in aerosols are well simulated by the model and necessary for reproducing the observed increase in SSR since 1990. European all-sky top of atmosphere aerosol radiative forcing increased by 3Wm-2 from 1970-2009.
Atmos. Chem. Phys. Discuss., 15, 13457-13513, doi:10.5194/acpd-15-13457-2015, 2015
Modeling organic aerosol composition at the puy de Dôme mountain (France) for two contrasted air masses with the WRF-Chem model
Atmos. Chem. Phys. Discuss., 15, 13395-13455, doi:10.5194/acpd-15-13395-2015, 2015
Composition, size distribution, optical properties and radiative effects of re-suspended local mineral dust of Rome area by individual-particle microanalysis and radiative transfer modelling
Summary: New information is given here on mineralogy, microphysical and optical properties, and radiative effects, of PM10 types from surface rocks at a non-desert site (Rome area, Italy). A large data set was built, by SEM XEDS microanalysis, of mineral particles (silicates, quartz and calcite, depending on rocks). Dust types show different size distribution, optical properties, and radiative effects. Radiative transfer modelling (6SV) based on SEM XEDS data is a further original feature of this work.
Atmos. Chem. Phys. Discuss., 15, 13347-13393, doi:10.5194/acpd-15-13347-2015, 2015
Global temperature response to the major volcanic eruptions in multiple reanalysis datasets
Summary: This paper evaluates the temperature response in the troposphere and the stratosphere to the three major and three smaller-scale volcanic eruptions between the 1960s and the 1990s. This paper provides intercomparison results for 9 reanalysis datasets for the volcanic temperature response and other naturally induced variabilities. It was found that the volcanic temperature response patterns differ not only between the major and smaller-scale eruptions but also among the major eruptions.
Atmos. Chem. Phys. Discuss., 15, 13315-13346, doi:10.5194/acpd-15-13315-2015, 2015
Trends in concentrations of atmospheric gaseous and particulate species in rural eastern Tennessee as related to primary emissions reductions
Atmos. Chem. Phys. Discuss., 15, 13211-13262, doi:10.5194/acpd-15-13211-2015, 2015
Vertical variations of aerosols and the effects responded to the emission control: application of lidar ceilometer in Beijing during APEC, 2014
Summary: The manuscript is the first paper to validate and discuss the high resolution vertical profiles of aerosols using Ceilometer in Beijing, China. We introduce the contribution to aerosols during the different air pollution episode in Beijing. Also, we seize the opportunity of emission reduction during APEC to study the contribution to aerosols. The results are helpful to provide guidance of redefining coordinated emission control strategies to control the regional pollution over Northern China.
Atmos. Chem. Phys. Discuss., 15, 13173-13209, doi:10.5194/acpd-15-13173-2015, 2015
Interactions among drainage flows, gravity waves and turbulence: a BLLAST case study
Summary: Stable-boundary-layer processes have been analysed using BLLAST data. Shallow drainage flows were formed at some locations after the near calm stage of the late afternoon. This stage ended with the arrival of a deeper wind associated with the mountain-plain circulation. At the same time, gravity waves were detected with an array of microbarometers. The interaction of these processes with turbulence was studied through Multi-Resolution Flux Decomposition at different sites and heights.
Atmos. Chem. Phys. Discuss., 15, 12821-12865, doi:10.5194/acpd-15-12821-2015, 2015
Seasonal trends in black carbon properties and co-pollutants in Mexico City
Summary: Extended measurements have been made of equivalent black carbon (eBC) derived from light absorption measurements made with a PAX over a 13 month period. The daily trends in eBC and other co-pollutants are evaluated with respect to season. The primary factors that led to large changes between the wet and dry seasons are the accelerated vertical mixing of boundary layer and free tropospheric air by the formation of clouds and decreased actinic flux that reduces the production of ozone.
Atmos. Chem. Phys. Discuss., 15, 12539-12582, doi:10.5194/acpd-15-12539-2015, 2015
Observations of new particle formation in enhanced UV irradiance zones near cumulus clouds
Summary: During the CARRIBA-campaign on Barbados 91 cases with increased aerosol particle number concentrations near clouds were detected from helicopter-borne measurements. Most of these cases are correlated with enhanced irradiance in the ultraviolet range. The events have a mean length of 100m corresponding to a lifetime of 300s, meaning a growth of several nm/h. Such high values cannot be explained by sulfuric acid alone thus probably extremely low volatile organic compounds are involved here.
Atmos. Chem. Phys. Discuss., 15, 12423-12452, doi:10.5194/acpd-15-12423-2015, 2015
A comparison of chemical mechanisms using Tagged Ozone Production Potential (TOPP) analysis
Summary: We show that simplified chemical mechanisms break down VOC into smaller sized degradation products on the first day faster than the near-explicit MCM chemical mechanism which would lead to an underprediction of ozone levels downwind of VOC emissions, and an underestimation of the VOC contribution to tropospheric background ozone when using simplified chemical mechanisms in regional or global modelling studies.
Atmos. Chem. Phys. Discuss., 15, 12389-12422, doi:10.5194/acpd-15-12389-2015, 2015
Use of criteria pollutants, active and passive mercury sampling, and receptor modeling to understand the chemical forms of gaseous oxidized mercury in Florida
Summary: Gaseous oxidized Hg (GOM) is a major contributor to Hg in wet and dry deposition. Recent work has indicated that the concentrations of GOM as measured are too low by 3-to-12 times; and that compounds vary across space and time. Data collected in Florida indicate five potential GOM compounds, including HgBr2, HgO, Hg(NO3)2, HgSO4, and an unknown compound. Sources include local combustion (cars and power plants), the marine boundary layer, and long range transport from Asia.
Atmos. Chem. Phys. Discuss., 15, 12069-12105, doi:10.5194/acpd-15-12069-2015, 2015
Effects of mineral dust on global atmospheric nitrate concentrations
Summary: We provide an assessment of the chemical composition and global aerosol load of aerosol nitrate and determine the effect of mineral dust on its formation due to thermodynamical interactions. For this purpose we used an explicit geographical representation of the emitted soil particle size distribution and chemical composition. We conclude that mineral dust aerosol chemistry is important for nitrate aerosol formation and significantly affects its global distribution, especially in the coarse mode
Atmos. Chem. Phys. Discuss., 15, 11525-11572, doi:10.5194/acpd-15-11525-2015, 2015
Quantifying the contribution of long-range transport to Particulate Matter (PM) mass loadings at a suburban site in the North-Western Indo Gangetic Plain (IGP)
Summary: We quantify the contribution of long range transport to PM levels in the NW-IGP through back trajectory climatology analysis. Transport from the west significantly enhanced coarse and fine mode PM mass loadings during all seasons. Local pollution episodes enhanced coarse mode PM only during winter and fine mode PM during winter and summer season. South easterly air masses (Source region: SE-IGP) were associated with significantly lower fine and coarse mode PM mass loadings during all seasons.
Atmos. Chem. Phys. Discuss., 15, 11409-11464, doi:10.5194/acpd-15-11409-2015, 2015
Variability of air ion concentrations in urban Paris
Atmos. Chem. Phys. Discuss., 15, 10629-10676, doi:10.5194/acpd-15-10629-2015, 2015
Source attribution and process analysis for atmospheric mercury in East China simulated by CMAQ-Hg
Summary: This study estimated the contributions to mercury concentration and deposition in East China from seven categories of emission sources by CMAQ-Hg. Also, this study focuses on diagnostic and process analysis for atmospheric mercury pollution formation and identification of the dominant atmospheric processes for mercury.
Atmos. Chem. Phys. Discuss., 15, 10389-10424, doi:10.5194/acpd-15-10389-2015, 2015
Detection of anthropogenic dust using CALIPSO lidar measurements
Atmos. Chem. Phys. Discuss., 15, 10163-10198, doi:10.5194/acpd-15-10163-2015, 2015
A Match-based approach to the estimation of polar stratospheric ozone loss using Aura Microwave Limb Sounder observations
Summary: Employing the well-established "Match" technique, we quantify polar stratospheric ozone loss during multiple Arctic and Antarctic winters, based on observations from the spaceborne Aura Microwave Limb Sounder (MLS) instrument. The dense MLS spatial coverage enables many more matches than is possible for balloon-based observations. Applying the same technique to MLS observations of the long-lived N2O molecule gives an measure of the impact of transport errors on our ozone loss estimates.
Atmos. Chem. Phys. Discuss., 15, 10041-10083, doi:10.5194/acpd-15-10041-2015, 2015
The influences of mass loading and rapid dilution of secondary organic aerosol on particle volatility
Summary: Secondary organic aerosol from the dark ozonolysis of α‑pinene was formed at a range of mass loadings from 1-800μg m-3. The amount of mass loss during evaporation in a thermodenuder was found to be independent of mass loading. A kinetic model of evaporation was fit to the observations and good agreement was obtained when the particle was either composed of dimers that decompose into semi-volatile monomers or when it was composed of low-volatility compounds that evaporate directly.
Atmos. Chem. Phys. Discuss., 15, 9997-10039, doi:10.5194/acpd-15-9997-2015, 2015
Development and optimization of a wildfire plume rise model based on remote sensing data inputs – Part 2
Summary: The transport of Biomass Burning emissions in Chemical Transport Model rely on parametrization of plumes injection height. Using fire observation selected to ensure match-up of fire-atmosphere-plume dynamics; a popular plume rise model was improved and optimized. The resulting model shows response to the effect of atmospheric stability consistent with previous findings and is able to predict higher injection height than any other tested parametrizations, giving a closer match with observation.
Atmos. Chem. Phys. Discuss., 15, 9815-9895, doi:10.5194/acpd-15-9815-2015, 2015
Meteor radar quasi two-day wave observations over 10 years at Collm (51.3° N, 13.0° E)
Atmos. Chem. Phys. Discuss., 15, 9631-9659, doi:10.5194/acpd-15-9631-2015, 2015
Vertical profiling of aerosol hygroscopic properties in the planetary boundary layer during the PEGASOS campaigns
Summary: This study presents PEGASOS project data from field campaigns in the Po Valley, Italy and the Netherlands. Vertical profiles of aerosol hygroscopicity and chemical composition were investigated with airborne measurements on board a Zeppelin NT airship. A special focus was on the evolution of different mixing layers within the PBL as a function of daytime. A closure study showed that variations in aerosol hygroscopicity can well be explained by the variations in chemical composition.
Atmos. Chem. Phys. Discuss., 15, 9445-9505, doi:10.5194/acpd-15-9445-2015, 2015
PLAM – a meteorological pollution index for air quality and its applications in fog-haze forecasts in north China
Summary: On the basis of parameterized meteorological condition principle method, this paper discussed the mutual impact of emission and meteorological condition, and studied the structure and function of meteorological conditions PLAM index in quantitatively identifying, diagnosing and forecasting large scope of fog-haze weather. A new model of PLAM/h – the meteorological pollution Index for air quality has been developed and used in NRT air quality forecasts, by considering both meteorology and polluta
Atmos. Chem. Phys. Discuss., 15, 9077-9106, doi:10.5194/acpd-15-9077-2015, 2015
Effect of gravity wave temperature fluctuations on homogeneous ice nucleation in the tropical tropopause layer
Atmos. Chem. Phys. Discuss., 15, 8771-8799, doi:10.5194/acpd-15-8771-2015, 2015
OMI tropospheric NO2 profiles from cloud slicing: constraints on surface emissions, convective transport and lightning NOx
Atmos. Chem. Phys. Discuss., 15, 8017-8072, doi:10.5194/acpd-15-8017-2015, 2015
Utilization of O4 slant column density to derive aerosol layer height from a spaceborne UV-visible hyperspectral sensor: sensitivity and case study
Summary: The sensitivities of oxygen-dimer (O4) slant column densities (SCDs) to changes in aerosol layer height are investigated using simulated radiances by a radiative transfer model, Linearized Discrete Ordinate Radiative Transfer (LIDORT), and Differential Optical Absorption Spectroscopy (DOAS) technique. A new algorithm is developed and tested to derive the aerosol effective height for cases over East Asia using radiance data from the Ozone Monitoring Instrument (OMI).
Atmos. Chem. Phys. Discuss., 15, 7933-7975, doi:10.5194/acpd-15-7933-2015, 2015
A comprehensive inventory of ship traffic exhaust emissions in the European sea areas in 2011
Summary: This manuscript describes the emissions from shipping in European sea areas. The work is based on automatic position reports (AIS) sent by ships and reflects realistic activity patterns of ships. The work demonstrates that it is feasible to construct a full bottom-up emission inventories based on large-volume activity data sets.
Atmos. Chem. Phys. Discuss., 15, 7459-7491, doi:10.5194/acpd-15-7459-2015, 2015
Analysis of CO2 mole fraction data: first evidence of large-scale changes in CO2 uptake at high northern latitudes
Summary: The two new results from our analysis are: 1) a significant revision to phase changes in atmospheric CO2 and 2) an indirect observation that is consistent with high northern latitude ecosystems actively taking up more CO2.
Atmos. Chem. Phys. Discuss., 15, 7089-7139, doi:10.5194/acpd-15-7089-2015, 2015
Ice nucleation terminology
Atmos. Chem. Phys. Discuss., 14, 22155-22162, doi:10.5194/acpd-14-22155-2014, 2014