Hygroscopic behavior of multicomponent organic aerosols and their internal mixtures with ammonium sulfate
Atmos. Chem. Phys. Discuss., 15, 23357-23405, doi:10.5194/acpd-15-23357-2015, 2015
Aerosol composition and variability in the Baltimore–Washington, DC region
Summary: Airborne measurements in Baltimore–Washington, DC allow for an understanding of the relationship between aerosol extinction which can be measured by satellites and mass which is used for air quality monitoring. Extinction was found to be driven to first-order by aerosol loadings; however, humidity-driven aerosol hydration plays an important secondary role. Spatial and diurnal variability in aerosol composition were small, but day-to-day variability aerosol hygroscopicity must be accounted for.
Atmos. Chem. Phys. Discuss., 15, 23317-23355, doi:10.5194/acpd-15-23317-2015, 2015
Retrieval of ammonia from ground-based FTIR solar spectra
Summary: We present a new retrieval method for ammonia(NH3) concentrations and total columns from ground based Fourier Transform InfraRed(FTIR) observations. Observations from Bremen, Lauder , Reunion and Jungfraujoch are used to show the capabilities of the new retrieval. The developed retrieval provides a new way to obtain time-resolved measurements and will be usefull for understanding the dynamics of ammonia concentrations in the atmosphere and for satellite and model validation.
Atmos. Chem. Phys. Discuss., 15, 23279-23315, doi:10.5194/acpd-15-23279-2015, 2015
Limited effect of anthropogenic nitrogen oxides on Secondary Organic Aerosol formation
Summary: Nitrogen oxides (NOx) play an important but complex role in secondary organic aerosol (SOA) formation. In this study we update the SOA scheme in a global 3D chemistry-climate model by implementing a 4-product volatility basis set (VBS) framework with NOx-dependent yields and simplified aging parameterizations. We find that the SOA decrease in response to a 50% reduction in anthropogenic NOx emissions is limited due to the buffering in different chemical pathways.
Atmos. Chem. Phys. Discuss., 15, 23231-23277, doi:10.5194/acpd-15-23231-2015, 2015
Wintertime aerosol chemical composition, volatility, and spatial variability in the greater London area
Summary: We investigate the spatial distribution of submicron aerosol in the greater London area as part of the Clean Air for London (ClearfLo) project in winter 2012. Although the concentrations of organic aerosol (OA) are similar between a rural and an urban site, the OA sources are different. We also examine the volatility of submicron aerosol at the rural site and find that the non-volatile organics have similar sources or have undergone similar chemical processing as refractory black carbon.
Atmos. Chem. Phys. Discuss., 15, 23173-23229, doi:10.5194/acpd-15-23173-2015, 2015
The impact of atmospheric mineral aerosol deposition on the albedo of snow and sea ice: are snow and sea ice optical properties more important than mineral aerosol optical properties?
Summary: The decrease in reflectivity (albedo) of sea ice and snow containing mineral dusts and volcanic ashes is calculated. The type of snow and sea ice, the thickness and the layering of mineral aerosol deposits are varied. The results show that the response of the albedo of snow and sea ice to mineral aerosol deposits is more sensitive to the type of snow or sea ice than to the properties of the mineral aerosol deposits themselves.
Atmos. Chem. Phys. Discuss., 15, 23131-23172, doi:10.5194/acpd-15-23131-2015, 2015
Sources of nitrogen deposition in Federal Class I areas in the US
Summary: Sources of nitrogen deposition (Ndep) in Federal Class I areas in the US are investigated, identifying unique features in contributions from different species, sectors and locations. Ndep in many parks is impacted by emissions several hundred km away; the role of oxidized vs reduced sources varies regionally. Emissions reductions in the western US most effectively reduce the extent of areas in critical load exceedance, while reductions in the east most effectively reduce exceedance magnitudes.
Atmos. Chem. Phys. Discuss., 15, 23089-23130, doi:10.5194/acpd-15-23089-2015, 2015
Delivery of anthropogenic bioavailable iron from mineral dust and combustion aerosols to the ocean
Summary: A new Fe dissolution scheme is developed and is applied to atmospheric chemistry transport model to estimate the anthropogenic Fe deposition. Our improved model successfully captured the inverse relationship of Fe solubility and total Fe loading. Our model estimated low end of Fe solubility, compared to that estimated by the previous studies. Our model results suggest that human activities contribute to more than half of the bioavailable Fe supply to significant portions of the oceans.
Atmos. Chem. Phys. Discuss., 15, 23051-23088, doi:10.5194/acpd-15-23051-2015, 2015
Urban stress-induced biogenic VOC emissions impact secondary aerosol formation in Beijing
Atmos. Chem. Phys. Discuss., 15, 23005-23049, doi:10.5194/acpd-15-23005-2015, 2015
Role of radiatively forced temperature changes in enhanced semi-arid warming over East Asia
Atmos. Chem. Phys. Discuss., 15, 22975-23004, doi:10.5194/acpd-15-22975-2015, 2015
Spatial, temporal and vertical distribution of ammonia concentrations over Europe – comparing a static and dynamic approach with WRF-Chem
Summary: In our study we aim at improving the basic understanding of ammonia in the atmosphere. We have also identified current limitations in relation to the governing processes that cause ammonia emissions and initial dispersion due to meteorological parameters. For this purpose we have implemented the emission from a dynamical ammonia model into the atmospheric transport model WRF-Chem and evaluated the model results against a static approach for describing the emissions and against measurements.
Atmos. Chem. Phys. Discuss., 15, 22935-22973, doi:10.5194/acpd-15-22935-2015, 2015
Characteristics and sources of submicron aerosols above the urban canopy (260 m) in Beijing, China during 2014 APEC summit
Summary: We have a comprehensive characterization of submicron aerosol composition and sources at 260 m in urban Beijing during APEC 2014. Aerosol species were shown to have substantial decreases of 40–80% during APEC, whereas the bulk composition was relatively similar as a result of synergetic controls of secondary precursors. Our results elucidated that the good air quality during APEC was the combined result of emission controls and meteorological effects, with the former playing the dominant role.
Atmos. Chem. Phys. Discuss., 15, 22889-22934, doi:10.5194/acpd-15-22889-2015, 2015
Aircraft-measured indirect cloud effects from biomass burning smoke in the Arctic and subarctic
Summary: Based on extensive aircraft campaigns, we quantify how biomass burning smoke affects subarctic and Arctic liquid cloud microphysical properties. Enhanced cloud albedo may decrease shortwave radiative flux by 2-4 W m-2 or more in some subarctic conditions. Smoke halved average cloud droplet diameter, and in one case study, it also appeared to limit droplet formation. Numerous Arctic background Aitken particles can also interact with combustion particles, perhaps affecting their properties.
Atmos. Chem. Phys. Discuss., 15, 22823-22887, doi:10.5194/acpd-15-22823-2015, 2015
Modeling study of the 2010 regional haze event in the North China Plain
Atmos. Chem. Phys. Discuss., 15, 22781-22822, doi:10.5194/acpd-15-22781-2015, 2015
Investigation of error sources in regional inverse estimates of greenhouse gas emissions in Canada
Summary: This paper uses synthetic data experiments to investigate the impacts of different error sources associated with prior flux, transport model and optimisation method on the atmospheric greenhouse gas inverse estimates. Results indicate that estimation errors are dominated by the transport model error and can propagate to the flux estimates non-linearly. It is necessary to obtain stable and realistic results in synthetic data experiments before a real observation-based inversion is performed.
Atmos. Chem. Phys. Discuss., 15, 22715-22779, doi:10.5194/acpd-15-22715-2015, 2015
Observation of a tidal effect on the Polar Jet Stream
Summary: This paper demonstrates for the first time a direct link between atmospheric tides and the Polar Jet Stream flow. The authors have identified an anti-correlation of the Arctic Oscillation with the horizontal (‘tractional’) tidal force acting at high latitudes, particularly during winter months. The tractional force varies strongly during the lunar month and with the 18.6 year precession cycle of the lunar orbit. Changes in Jet Stream flow have a large effect on winter weather.
Atmos. Chem. Phys. Discuss., 15, 22701-22713, doi:10.5194/acpd-15-22701-2015, 2015
Investigations of boundary layer structure, cloud characteristics and vertical mixing of aerosols at Barbados with large eddy simulations
Summary: Large eddy simulations (LES) are performed for the area of the Caribbean island Barbados to investigate island effects on boundary layer modification, cloud generation and vertical mixing of aerosols. Incoming Saharan dust layers are analyzed and effects of layer thinning, subsidence and turbulent downward transport become apparent, which are sensitive to atmospheric stability and wind shear. Comparisons of LES model output with Doppler wind lidar data are made to validate the modeling results.
Atmos. Chem. Phys. Discuss., 15, 22637-22699, doi:10.5194/acpd-15-22637-2015, 2015
New insight into the spatiotemporal variability and source apportionments of C1–C4 alkyl nitrates in Hong Kong
Atmos. Chem. Phys. Discuss., 15, 22597-22636, doi:10.5194/acpd-15-22597-2015, 2015
Introduction: The Pan-Eurasian Experiment (PEEX) – multi-disciplinary, multi-scale and multi-component research and capacity building initiative
Atmos. Chem. Phys. Discuss., 15, 22567-22596, doi:10.5194/acpd-15-22567-2015, 2015
Seasonal variation of ozone and black carbon observed at Paknajol, an urban site in the Kathmandu Valley, Nepal
Summary: The aim of this paper is to present a full year analysis of simultaneous measurements of ozone, black carbon and aerosol number concentration at Paknajol, in the Kathmandu Valley, one of the global “hot spots” in terms of air pollution. Results indicate persisting poor air quality conditions throughout all the measurement period, and suggest that the pollutants variability is mainly driven by local pollution sources activity, local and large-scale dynamics, photochemistry and vegetation fires.
Atmos. Chem. Phys. Discuss., 15, 22527-22566, doi:10.5194/acpd-15-22527-2015, 2015
Possible influence of atmospheric circulations on winter hazy pollution in Beijing-Tianjin-Hebei region, northern China
Atmos. Chem. Phys. Discuss., 15, 22493-22526, doi:10.5194/acpd-15-22493-2015, 2015
The radiative impact of desert dust on orographic rain in the Cevennes–Vivarais area: a case study from HyMeX
Summary: We analyze the direct radiative impact of an intense African dust plume on orographic precipitation in the Western Mediterranean in the fall of 2012 using high resolution simulations from a convection permitting mesoscale model validated against measurements acquired during the first special observation period of HyMeX. We show that the dust direct radiative effect in such a dynamical environment is not sufficient to impact 24-h accumulated rainfall in the dusty simulation.
Atmos. Chem. Phys. Discuss., 15, 22451-22492, doi:10.5194/acpd-15-22451-2015, 2015
Annual variations of carbonaceous PM2.5 in Malaysia: influence by Indonesian peatland fires
Atmos. Chem. Phys. Discuss., 15, 22419-22449, doi:10.5194/acpd-15-22419-2015, 2015
Seasonal characterization of submicron aerosol chemical composition and organic aerosol sources in the southeastern United States: Atlanta, Georgia and Look Rock, Tennessee
Atmos. Chem. Phys. Discuss., 15, 22379-22417, doi:10.5194/acpd-15-22379-2015, 2015
Speciated measurements of semivolatile and intermediate volatility organic compounds (S/IVOCs) in a pine forest during BEACHON-RoMBAS 2011
Summary: Using a novel instrument, we have made measurements of organic compounds that can existing as a gas or particle in the rural atmosphere. Through hourly measurements, we have identified the sources and atmospheric processes of these compounds, which are important for modeling the climate and health impact of these emissions.
Atmos. Chem. Phys. Discuss., 15, 22331-22377, doi:10.5194/acpd-15-22331-2015, 2015
Upper tropospheric water vapour variability at high latitudes – Part 1: Influence of the annular modes
Atmos. Chem. Phys. Discuss., 15, 22291-22329, doi:10.5194/acpd-15-22291-2015, 2015
Volatility of organic aerosol and its components in the Megacity of Paris
Atmos. Chem. Phys. Discuss., 15, 22263-22289, doi:10.5194/acpd-15-22263-2015, 2015
Fine particulate matter associated with monsoonal effect and the responses of biomass fire hotspots in the tropical environment
Summary: Trans-boundary haze pollution is a major health and environmental concern during south-west and north-east monsoon in the South East Asian (SEA) regions. The concentration of PM2.5 exceeds the tolerable limits (WHO; USA EPA) during the summer monsoon. The novelty of this study is the source characterization of PM2.5 and source-specific risk assessment during intense haze pollution which are yet to be addressed in this region. The outcomes of this study will give an insight about future implicati
Atmos. Chem. Phys. Discuss., 15, 22215-22261, doi:10.5194/acpd-15-22215-2015, 2015
A sub-decadal trend of diacids in atmospheric aerosols in East Asia
Summary: The chemistry-transport models have predicted the change of secondary organic aerosols (SOA) in the future atmosphere with a large uncertainty. This study measures the change of diacids, major water-soluble surrogates of SOA, over a sub-decadal scale in atmospheric aerosols in East Asia. Diacids are observed to increase by 3.9 – 47.4% per year. If the increases continued, the water-soluble fraction of SOA would increase significantly in the future atmosphere in East Asia.
Atmos. Chem. Phys. Discuss., 15, 22183-22213, doi:10.5194/acpd-15-22183-2015, 2015
Polar Stratospheric Cloud evolution and chlorine activation measured by CALIPSO and MLS, and modelled by ATLAS
Summary: This paper presents the first trial of analyzing amount of chlorine activation on different PSC compositions by using match analysis on trajectories initiated from PSC locations identified by CALIPSO/CALIOP measurements. The measured minor species such as HCl and ClO by MLS are compared with ATLAS chemistry-transport model (CTM) results. PSC growth to NAT, NAT/STS mixture, and ice were identified by different temperature decrease histories on trajectories.
Atmos. Chem. Phys. Discuss., 15, 22141-22182, doi:10.5194/acpd-15-22141-2015, 2015
Detailed budget analysis of HONO in central London reveals a missing daytime source
Summary: This paper presents field measurements of HONO and a range of other gas phase and particulate species from an urban background site in London. The measured daytime HONO cannot be reproduced with a simple box model and thus a significant daytime missing source of HONO is present. We show that this missing source could be responsible for 40% of the OH radical source and 57% of the OH initiation, hence it's potential importance for atmospheric oxidation and ozone production.
Atmos. Chem. Phys. Discuss., 15, 22097-22139, doi:10.5194/acpd-15-22097-2015, 2015
OH reactivity and concentrations of Biogenic Volatile Organic Compounds in a Mediterranean forest of downy oak trees
Summary: Our manuscript shows results of OH reactivity and Biogenic Volatile Organic Compounds (BVOCs) concentration during a field experiment conducted in late spring 2014 at the Observatoire de Haute Provence (OHP) site. We found that OH reactivity is among the highest measured in forests globally (69s-1) and it is mainly due to isoprene. No missing reactivity was present during daytime inside or above the canopy, while 50% missing reactivity was found by night at both heights.
Atmos. Chem. Phys. Discuss., 15, 22047-22095, doi:10.5194/acpd-15-22047-2015, 2015
Variability of water vapour in the Arctic stratosphere
Atmos. Chem. Phys. Discuss., 15, 22013-22045, doi:10.5194/acpd-15-22013-2015, 2015
Viscosity controls humidity dependence of N2O5 uptake to citric acid aerosol
Summary: The heterogeneous loss of N2O5 to citric acid aerosol, a proxy for highly oxygenated secondary organic aerosol, is shown to be substantially lower than to other aqueous organic aerosol proxies investigated previously. This is attributed to the widely changing viscosity within the atmospherically relevant humidity range. It may explain some of the unexpectedly low loss rates of N2O5 to aerosol particles derived from in field studies.
Atmos. Chem. Phys. Discuss., 15, 21983-22011, doi:10.5194/acpd-15-21983-2015, 2015
A method to retrieve super-thin cloud optical depth over ocean background with polarized sunlight
Atmos. Chem. Phys. Discuss., 15, 21959-21982, doi:10.5194/acpd-15-21959-2015, 2015
Real-time measurements of secondary organic aerosol formation and aging from ambient air in an oxidation flow reactor in the Los Angeles area
Summary: An Oxidation Flow Reactor (OFR) was deployed to study secondary organic aerosol (SOA) formation and aging of urban emissions at a wide range of OH exposures during the CalNex campaign in Pasadena, CA, in 2010. Results include linking SOA formation to short-lived reactive compounds, similar elemental composition of reactor-aged emissions to atmospheric aging, changes in OA mass due to condensation of oxidized gas-phase species and heterogeneous oxidation of particle-phase species.
Atmos. Chem. Phys. Discuss., 15, 21907-21958, doi:10.5194/acpd-15-21907-2015, 2015
An adsorption theory of heterogeneous nucleation of water vapour on nanoparticles
Summary: Heterogeneous nucleation is a phenomenon that starts the condensation of supersaturated vapors on solid surfaces. An example is the formation of cirrus clouds in the atmosphere: their formation is often triggered at relative humidities clearly above 100%. We derive a new theory that can be used to calculate the threshold supersaturation of heterogeneous nucleation of water vapor on nanoparticles, and show that it performs significantly better than older theories when compared to lab experiments.
Atmos. Chem. Phys. Discuss., 15, 21883-21906, doi:10.5194/acpd-15-21883-2015, 2015
Radiative and climate impacts of a large volcanic eruption during stratospheric sulfur geoengineering
Summary: We have studied the impacts of a volcanic eruption during solar radiation management (SRM) using an aerosol-climate model ECHAM5-HAM-SALSA and an Earth system model MPI-ESM. A volcanic eruption during stratospheric sulfur geoengineering would lead to larger particles and smaller amount of new particles than if volcano erupts in normal atmospheric conditions. Thus, volcanic eruption during SRM would lead to only a small additional cooling which would last for a significantly shorter period.
Atmos. Chem. Phys. Discuss., 15, 21837-21881, doi:10.5194/acpd-15-21837-2015, 2015
Seasonality of ultrafine and sub-micron aerosols and the inferences on particle formation processes
Summary: This study investigated the properties of ultrafine (UFPs) and submicron particles (PM1) in an East-Asian urban area. The results indicate that the concentration of PM1 was elevated during cold seasons, whereas the highest UFPs concentration was measured in summer. Moreover, UFPs were composed mostly of organics, whereas ammonium and sulfate were the major constituents in PM1. This study underlines the significance of secondary organic aerosols in UFPs.
Atmos. Chem. Phys. Discuss., 15, 21803-21835, doi:10.5194/acpd-15-21803-2015, 2015
Validation of farm-scale methane emissions using nocturnal boundary layer budgets
Atmos. Chem. Phys. Discuss., 15, 21765-21802, doi:10.5194/acpd-15-21765-2015, 2015
Biomass burning emissions and potential air quality impacts of volatile organic compounds and other trace gases from temperate fuels common in the United States
Summary: A comprehensive suite of instruments was used to quantify the emissions of over 200 organic and inorganic gases from 56 laboratory burns of 18 different biomass fuel types common in the Southeastern, Southwestern, or Northern United States. Emission ratios relative to carbon monoxide (CO) are used to characterize the composition of gases emitted by mass; OH reactivity; and potential secondary organic aerosol (SOA) precursors for the 3 different U.S. fuel regions presented here.
Atmos. Chem. Phys. Discuss., 15, 21713-21763, doi:10.5194/acpd-15-21713-2015, 2015
Understanding cirrus ice crystal number variability for different heterogeneous ice nucleation spectra
Summary: We use the adjoint model of a cirrus parameterization to quantify sources of crystal variability for various ice-nucleating spectra and output from CAM5. The sensitivities can be directly linked to nucleation regime and efficiency of various INP. The lab-based spectrum calculates much higher INP efficiencies than field-based ones, owing to aerosol surface properties. The sensitivity to temperature tends to be low, due to the compensating effects of temperature on INP spectrum parameters.
Atmos. Chem. Phys. Discuss., 15, 21671-21711, doi:10.5194/acpd-15-21671-2015, 2015
Size distribution and optical properties of mineral dust aerosols transported in the western Mediterranean
Summary: This study investigates the size distribution, chemical composition and optical properties of Saharan mineral dust transported over the Western Mediterranean using in-situ measurements collected from aircraft. Their variability due to altitude, time of transport and mixing rate with pollution particles are discussed. We found a moderate light absorption of the dust plumes even in presence of pollution particles and the persistence of large dust particles after transport in the Mediterranean.
Atmos. Chem. Phys. Discuss., 15, 21607-21669, doi:10.5194/acpd-15-21607-2015, 2015
Measurement-based direct radiative effect by brown carbon over Indo-Gangetic Plain
Summary: There are relatively few measurement-based estimates for the direct radiative effect of brown carbon so far. This is first time that the direct radiative effect of brown carbon is estimated by exploiting the AERONET-retrieved imaginary indices. We estimated it for four sites in Indo-Gangetic Plain: Karachi, Lahore, Kanpur and Gandhi College.
Atmos. Chem. Phys. Discuss., 15, 21583-21606, doi:10.5194/acpd-15-21583-2015, 2015
Influence of biomass burning on CCN number and hygroscopicity during summertime in the eastern Mediterranean
Summary: BBOA from long-range transport exhibits increased CCN concentrations for particles larger than 100 nm. At the same time the hygroscopicity parameter decreased for all particle sizes, as sub-100 nm particles appear to be richer in less hygroscopic, organic material while larger particles become less hygroscopic due to condensation of less hygroscopic gaseous compounds. Finally, atmospheric processing of freshly-emitted BBOA to more oxidized organic aerosol can result in a 2-fold increase of κ_org
Atmos. Chem. Phys. Discuss., 15, 21539-21582, doi:10.5194/acpd-15-21539-2015, 2015
The tropopause inversion layer in baroclinic life cycles experiments: the role of diabatic and mixing processes
Summary: By conducting various simulations of dry and moist baroclinic life cycles we aimed to improve the understanding whether dynamical or diabatic processes are more relevant to form a tropopause inversion layer at midlatitudes. Most importantly, our experiments highlighted the role of different moisture related processes for the formation and evolution of the tropopause inversion layer with varying relevance and strength in different phases of the baroclinic life cycles.
Atmos. Chem. Phys. Discuss., 15, 21495-21537, doi:10.5194/acpd-15-21495-2015, 2015
Distinguishing the drivers of trends in land carbon fluxes and plant volatile emissions over the past three decades
Summary: We estimate decadal trends in land carbon fluxes and emissions of biogenic volatile organic compounds (BVOCs) during 1982-2011, with a focus on the feedback from biosphere (such as tree growth and phenology). Increases of LAI at peak season accounts for ~25% of the trends in GPP and isoprene emissions at the northern lands. However, phenological change alone does not promote regional carbon uptake and BVOC emissions.
Atmos. Chem. Phys. Discuss., 15, 21449-21494, doi:10.5194/acpd-15-21449-2015, 2015
Identification of particulate organosulfates in three megacities at the middle and lower reaches of the Yangtze River
Atmos. Chem. Phys. Discuss., 15, 21415-21448, doi:10.5194/acpd-15-21415-2015, 2015
Reactive nitrogen partitioning and its relationship to winter ozone events in Utah
Summary: High wintertime ozone levels have been observed in the Uintah Basin, Utah, a sparsely populated rural region with intensive oil and gas operations. The reactive nitrogen budget plays an important role in tropospheric ozone formation, and we find that nighttime chemistry has a large effect on its partitioning. Much of the oxidation of reactive nitrogen during a high-ozone year occurred via heterogeneous uptake onto aerosol at night, keeping NOx at concentrations comparable to a low-ozone year.
Atmos. Chem. Phys. Discuss., 15, 21383-21413, doi:10.5194/acpd-15-21383-2015, 2015
Global and regional emissions estimates of 1,1-difluoroethane (HFC-152a, CH3CHF2) from in situ and air archive observations
Summary: We report regional and global emissions estimates of HFC-152a using high frequency measurements from 11 observing sites and archived air samples dating back to 1978 together with atmospheric transport models. The ‘bottom up’ emissions of HFC-152a reported to the UNFCCC appear to significantly underestimate those reported here from observations. This discrepancy we suggest arises from largely underestimated USA and undeclared Asian emissions.
Atmos. Chem. Phys. Discuss., 15, 21335-21381, doi:10.5194/acpd-15-21335-2015, 2015
Contributions of dust and biomass-burning to aerosols at a Colorado mountain-top site
Atmos. Chem. Phys. Discuss., 15, 21299-21334, doi:10.5194/acpd-15-21299-2015, 2015
Spring and summer contrast in new particle formation over nine forest areas in North America
Summary: Role of low volatility organics in new particle formation (NPF) in the atmosphere is assessed. An empirical formulation in which formation rate is a function of the concentrations of sulfuric acid and low volatility organics significantly overpredicts NPF in the summer. Two different schemes predict quite different nucleation rates (including their spatial patterns), concentrations of cloud condensation nuclei, and aerosol first indirect radiative forcing in North America.
Atmos. Chem. Phys. Discuss., 15, 21271-21298, doi:10.5194/acpd-15-21271-2015, 2015
Parameterization of oceanic whitecap fraction based on satellite observations
Summary: Sea spray source functions (SSSFs) predict production of sea salt aerosol, important for climate. Sea spray is generated by bubble bursting within whitecaps, which are mainly formed by wind speed U. To improve SSSFs, we examine variations of whitecap fraction W with U and secondary factors. Assessing U dependence of satellite-based W on a global scale, we find a quadratic power law for W(U). Regional scale assessment suggests that this W(U) relationship implicitly accounts for secondary factors.
Atmos. Chem. Phys. Discuss., 15, 21219-21269, doi:10.5194/acpd-15-21219-2015, 2015
Instantaneous longwave radiative impact of ozone: an application on IASI/MetOp observations
Atmos. Chem. Phys. Discuss., 15, 21177-21218, doi:10.5194/acpd-15-21177-2015, 2015
Ozone and carbon monoxide over India during the summer monsoon: regional emissions and transport
Summary: We compare simulations of ozone and carbon monoxide using a regional chemistry transport model (WRF-Chem) with aircraft observations from CARIBIC program over India during monsoon period. Sensitivity simulations are conducted to assess the influences of regional emissions and long-range transport.
Atmos. Chem. Phys. Discuss., 15, 21133-21176, doi:10.5194/acpd-15-21133-2015, 2015
Carbonyl sulfide exchange in soils for better estimates of ecosystem carbon uptake
Summary: We constructed a model of carbonyl sulfide soil exchange sufficient for predicting outcomes in terrestrial ecosystems. Empirical observations combined with soil gas exchange theory reveal simultaneous abiotic production and biotic uptake mechanisms. Measurement of atmospheric carbonyl sulfide is an emerging tool to quantify photosynthesis at important temporal and spatial scales.
Atmos. Chem. Phys. Discuss., 15, 21095-21132, doi:10.5194/acpd-15-21095-2015, 2015
Conceptual design of a measurement network of the global change
Atmos. Chem. Phys. Discuss., 15, 21063-21093, doi:10.5194/acpd-15-21063-2015, 2015
How to most effectively expand the global surface ozone observing network
Summary: We explore the global representativeness of a global surface ozone dataset from a range of perspectives (area, biomes, chemical regimes, model uncertainty, model trends). We conclude that the current network fails to provide sufficient constraints for important regions / regimes leading to uncertainty for a range of atmospheric composition challenges. We suggest 20 new locations for making surface ozone observations which would significantly enhance our observational capability.
Atmos. Chem. Phys. Discuss., 15, 21025-21061, doi:10.5194/acpd-15-21025-2015, 2015
Iodine's impact on tropospheric oxidants: a global model study in GEOS-Chem
Summary: Using a global chemical transport model (GEOS-Chem) with additional iodine emissions, chemistry and deposition we show that iodine is responsible for ~9% of global ozone loss but has negligible impacts on global OH. Uncertainties are large in the chemistry and emissions and future research is needed in both. Measurements of iodine species (especially HOI) would be useful. We believe iodine chemistry should be considered in future chemistry-climate and in air quality modeling.
Atmos. Chem. Phys. Discuss., 15, 20957-21023, doi:10.5194/acpd-15-20957-2015, 2015
Remote sensing of soot carbon – Part 2: Understanding the absorption Angstrom exponent
Atmos. Chem. Phys. Discuss., 15, 20911-20956, doi:10.5194/acpd-15-20911-2015, 2015
Sensitivities of UK PM2.5 concentrations to emissions reductions
Atmos. Chem. Phys. Discuss., 15, 20881-20910, doi:10.5194/acpd-15-20881-2015, 2015
Inverse modeling of black carbon emissions over China using ensemble data assimilation
Summary: An ensemble optimal interpolation (EnOI) data assimilation technique is used to investigate the possibility of optimally recovering the spatially resolved emissions bias of BC. The inversed emission over China in January is 240.1Gg, and annual emission is about 2750Gg. Even though only monthly mean BC measurements are employed to inverse the emissions, the accuracy of the daily model simulation improves. We finds that EnOI is a useful and computation-free method to make top-down estimation.
Atmos. Chem. Phys. Discuss., 15, 20851-20879, doi:10.5194/acpd-15-20851-2015, 2015
Size distributions of polycyclic aromatic hydrocarbons in urban atmosphere: sorption mechanism and source contributions to respiratory deposition
Atmos. Chem. Phys. Discuss., 15, 20811-20850, doi:10.5194/acpd-15-20811-2015, 2015
Putting the clouds back in aerosol-cloud interactions
Summary: Aerosols affect cloud properties, and the radiative effects of clouds. Human emissions of aerosol particles and precursors may alter the radiative effects of clouds. This is generally a cooling effect that offsets other warming effects of human emissions of gases. Simulating these aerosol effects on clouds are highly dependent on the formulation of the microphysical (cloud droplet scale) processes. This work uses model simulations to show these effects are large, and depend on certain processes.
Atmos. Chem. Phys. Discuss., 15, 20775-20810, doi:10.5194/acpd-15-20775-2015, 2015
Toward enhanced capability for detecting and predicting dust events in the Western United States: the Arizona Case Study
Summary: We developed dust records in Arizona in 2005-2013 using multiple surface and remote sensing observation datasets. They were anti-correlated with three drought indicators (PDSI, satellite NDVI and soil moisture). Surface observations indicated stronger and more frequent dust events in the afternoon than in the morning due to faster winds and drier soil. We show that the National Air Quality Forecasting Capability CMAQ model captured a recent dust event accompanied by stratospheric ozone intrusion
Atmos. Chem. Phys. Discuss., 15, 20743-20774, doi:10.5194/acpd-15-20743-2015, 2015
Evaluation of VIIRS, GOCI, and MODIS Collection 6 AOD retrievals against ground sunphotometer measurements over East Asia
Summary: Using ground AOD measurements from AERONET, DRAGON-Asia Campaign, and handheld sunphotometers, we evaluated emerging aerosol products from VIIRS, GOCI, and Terra and Aqua MODIS (Collection 6) in East Asia in 2012-2013. We found that satellite aerosol products performed better in tracking the day-to-day variability than the high-resolution spatial variability. VIIRS EDR and GOCI products provided the most accurate AOD retrievals, while VIIRS IP and MODIS C6 3km products had positive biases.
Atmos. Chem. Phys. Discuss., 15, 20709-20741, doi:10.5194/acpd-15-20709-2015, 2015
Sensitivity of simulated CO2 concentration to sub-annual variations in fossil fuel CO2 emissions
Atmos. Chem. Phys. Discuss., 15, 20679-20708, doi:10.5194/acpd-15-20679-2015, 2015
On the emissions and transport of bromoform: sensitivity to model resolution and emission location
Summary: We find a strong regional element to the uplift of CHBr3 from the ocean to the upper troposphere and lower stratosphere. The strongest uplift occurs when the largest emission and the most intense convection are co-located which is over the Maritime Continent in northern winter. Estimates of CHBr3 emissions based on aircraft measurements will be sensitive to where the available aircraft campaigns took place.
Atmos. Chem. Phys. Discuss., 15, 20655-20678, doi:10.5194/acpd-15-20655-2015, 2015
Hydrolysis and gas-particle partitioning of organic nitrates formed from the oxidation of α-pinene in environmental chamber experiments
Summary: The fate of organic nitrates influences their role as sinks and sources of NOx and their effects on the formation of tropospheric ozone and organic aerosol. Organic nitrates were formed from the photo-oxidation of α-pinene in environmental chamber experiments. Results on partitioning and hydrolysis of organic nitrates from this work could be implemented in chemical transport models to more accurately represent the fate of NOx and the formation of ozone and particulate matter.
Atmos. Chem. Phys. Discuss., 15, 20629-20653, doi:10.5194/acpd-15-20629-2015, 2015
Meteorological constraints on oceanic halocarbons above the Peruvian Upwelling
Atmos. Chem. Phys. Discuss., 15, 20597-20628, doi:10.5194/acpd-15-20597-2015, 2015
Secondary Organic Aerosol formation from isoprene photooxidation during cloud condensation–evaporation cycles
Summary: The impact of cloud events on isoprene secondary organic aerosol (SOA) formation has been studied from an isoprene/NOx/light system in an atmospheric simulation chamber. aqSOA formation can be linked to water soluble volatile organic compounds dissolution in the aqueous phase and to further aqueous phase reactions. Cloud-induced SOA formation is experimentally demonstrated in this study, thus highlighting the importance of aqueous multiphase systems in atmospheric SOA formation estimations.
Atmos. Chem. Phys. Discuss., 15, 20561-20596, doi:10.5194/acpd-15-20561-2015, 2015
Size-resolved measurements of ice nucleating particles at six locations in North America and one in Europe
Atmos. Chem. Phys. Discuss., 15, 20521-20559, doi:10.5194/acpd-15-20521-2015, 2015
The impact of residential combustion emissions on atmospheric aerosol, human health and climate
Summary: We estimate the impact of residential emissions (cooking and heating) on atmospheric aerosol, human health and climate. We find large contributions to annual mean ambient PM2.5 in residential sources regions resulting in significant but uncertain global premature mortality when key uncertainties in emission flux are considered. We show that residential emissions exert an uncertain global radiative effect, and suggest more work is needed to characterise residential emissions climate importance.
Atmos. Chem. Phys. Discuss., 15, 20449-20520, doi:10.5194/acpd-15-20449-2015, 2015
The imprint of stratospheric transport on column-averaged methane
Summary: We find that stratospheric model-transport errors are common for chemical transport models that are used for inverse estimates of CH4 emissions. These model-transport errors cause latitudinal as well as seasonal biases in simulated stratospheric and, hence, column-averaged CH4 mixing ratios (XCH4). Such a model bias corresponds to an overestimation of arctic and mid-latitude CH4 emissions if inversion studies do not apply an ad hoc bias correction before inverting fluxes from XCH4 observations.
Atmos. Chem. Phys. Discuss., 15, 20395-20447, doi:10.5194/acpd-15-20395-2015, 2015
Effects of dust particle internal structure on light scattering
Summary: Internal structures are a common in atmospheric dust particles, yet their effects on light scattering are largely unstudied. In this work, we study how hematite nodes, internal voids and hematite-rich coating impact single-scattering properties of computationally generated irregular model particles. The results show that all of these features change scattering properties significantly, and that a simple effective-medium approximation is not enough to replicate the scattering properties.
Atmos. Chem. Phys. Discuss., 15, 20349-20394, doi:10.5194/acpd-15-20349-2015, 2015
Implications of model bias in carbon monoxide for methane lifetime
Summary: A low bias in carbon monoxide (CO) at northern latitudes is a common feature of chemistry climate models. We find that increasing northern hemisphere (NH) CO emissions or reducing NH OH concentrations improves the agreement with CO surface observations, but reducing NH OH leads to a better comparison with MOPITT. Removing model biases in ozone and water vapor increases the simulated methane lifetime, but does not give the 20% reduction in NH OH suggested by our analysis the CO bias.
Atmos. Chem. Phys. Discuss., 15, 20305-20348, doi:10.5194/acpd-15-20305-2015, 2015
Change in turbopause altitude at 52 and 70° N
Summary: Turbulent energy dissipation rates are calculated using MF-radar signals from 70°N and 52°N for the period 2001-2014 inclusive, and are used to estimate turbopause altitudes. A positive trend in turbopause altitude is identified for 70°N in summer, but not in winter and not at 52°N. The turbopause altitude change between 2001 and 2014 can be used to hypothesize a corresponding change in atomic oxygen concentration.
Atmos. Chem. Phys. Discuss., 15, 20287-20304, doi:10.5194/acpd-15-20287-2015, 2015
Forty years of improvements in European air quality: the role of EU policy–industry interplay
Atmos. Chem. Phys. Discuss., 15, 20245-20285, doi:10.5194/acpd-15-20245-2015, 2015
Estimation of continuous anthropogenic CO2 using CO2, CO, δ13C(CO2) and Δ14C(CO2)
Summary: In this model sensitivity study we compare and evaluate the surrogate tracers CO2, CO, δ13C-CO2 and Δ14C-CO2 for estimating continuous anthropogenic CO2. The results can be used to optimize the measurement network design with respect to the partitioning of total CO2 into biospheric and anthropogenic CO2 contributions. This enables improvement and validation of highly resolved emission inventories using atmospheric observation and regional modelling.
Atmos. Chem. Phys. Discuss., 15, 20181-20243, doi:10.5194/acpd-15-20181-2015, 2015
Ice melt, sea level rise and superstorms: evidence from paleoclimate data, climate modeling, and modern observations that 2 °C global warming is highly dangerous
Summary: We suggest that ice sheet disintegration is a highly nonlinear process and poses a danger of rapid sea level rise. We find evidence in paleoclimate observations and in global climate simulations supporting the existence of amplifying feedback processes that would contribute to nonlinear ice sheet response. Modern observations reveal that these processes are already underway, including cooling of the Southern Ocean surface. We conclude that a 2°C limit on global warming is not a safe “guardrail".
Atmos. Chem. Phys. Discuss., 15, 20059-20179, doi:10.5194/acpd-15-20059-2015, 2015
Characterization of PM10 sources in the central Mediterranean
Atmos. Chem. Phys. Discuss., 15, 20013-20057, doi:10.5194/acpd-15-20013-2015, 2015
Development of an atmospheric N2O isotopocule model and optimization procedure, and application to source estimation
Summary: We developed an atmospheric N2O isotopocule model based on a chemistry-coupled atmospheric general circulation model and a simple method to optimize the model, and estimated the isotopic signatures of surface sources at the hemispheric scale. Data obtained from ground-based observations, measurements of firn air, and balloon and aircraft flights were used to optimize the long-term trends, interhemispheric gradients, and photolytic fractionation, respectively, in the model.
Atmos. Chem. Phys. Discuss., 15, 19947-20011, doi:10.5194/acpd-15-19947-2015, 2015
Cloud condensation nuclei activity, droplet growth kinetics and hygroscopicity of biogenic and anthropogenic Secondary Organic Aerosol (SOA)
Summary: This study investigated the cloud droplet activation behavior and hygroscopic growth of mixed anthropogenic and biogenic SOA (ABSOA) compared to pure biogenic SOA (BSOA) and pure anthropogenic SOA (ASOA). Cloud droplet activation behaviors of different types of SOA were similar. In contrast, the hygroscopicity of ASOA was higher than BSOA and ABSOA. ASOA components enhanced the hygroscopicity of the ABSOA. Yet this enhancement cannot be described by a linear mixing of pure SOA systems.
Atmos. Chem. Phys. Discuss., 15, 19903-19945, doi:10.5194/acpd-15-19903-2015, 2015
Plant surface reactions: an ozone defence mechanism impacting atmospheric chemistry
Summary: “Breathing” ozone can have harmful effects on sensitive vegetation when sufficient ozone enters the plant leaves through the stomatal pores. Here we show that cis-abienol, a semi-volatile organic compound secreted by the leaf hairs (trichomes) of various tobacco varieties, protects the leaves from “breathing" ozone. Ozone is efficiently removed by chemical reactions with cis-abienol at the plant surface, forming oxygenated VOC (formaldehyde and methyl vinyl ketone) that are released into the air
Atmos. Chem. Phys. Discuss., 15, 19873-19902, doi:10.5194/acpd-15-19873-2015, 2015
Variation of the radiative properties during black carbon aging: theoretical and experimental intercomparison
Atmos. Chem. Phys. Discuss., 15, 19835-19872, doi:10.5194/acpd-15-19835-2015, 2015
Hygroscopicity of nanoparticles produced from homogeneous nucleation in the CLOUD experiments
Summary: The hygroscopicity of nucleated nanoparticles was measured in the presence of sulfuric acid, sulfuric acid-dimethylamine, and sulfuric acid-organics derived from α-pinene oxidation during CLOUD 7 at CERN in 2012. The hygroscopicity parameter κ decreased with increasing particle size indicating decreasing acidity of particles.
Atmos. Chem. Phys. Discuss., 15, 19803-19833, doi:10.5194/acpd-15-19803-2015, 2015
Modeling particle nucleation and growth over northern California during the 2010 CARES campaign
Atmos. Chem. Phys. Discuss., 15, 19729-19801, doi:10.5194/acpd-15-19729-2015, 2015
Overview of the Chemistry-Aerosol Mediterranean Experiment/Aerosol Direct Radiative Forcing on the Mediterranean Climate (ChArMEx/ADRIMED) summer 2013 campaign
Summary: The aim of this article is to present an experimental campaign over the Mediterranean focused on aerosol-radiation measurements and modeling. Results indicate an important atmospheric loading associated with a moderate absorbing ability of mineral dust. Observations suggest a complex vertical structure and size distributions characterized by large aerosols within dust plumes. The radiative effect is highly variable, with negative forcing over the Mediterranean and positive over northern Africa.
Atmos. Chem. Phys. Discuss., 15, 19615-19727, doi:10.5194/acpd-15-19615-2015, 2015
Dehydration effects from contrails in a coupled contrail–climate model
Atmos. Chem. Phys. Discuss., 15, 19553-19613, doi:10.5194/acpd-15-19553-2015, 2015
Updated ozone absorption cross section will reduce air quality compliance
Summary: As an air pollutant, O3 is monitored photometrically to assess compliance with air quality legislation. A recent study found a 1.8% reduction in its absorption cross section which would lead to an equivalent increase in observed O3 concentrations. We estimate this would increase the number of sites out of compliance with air quality regulations in the EU and US by 20%. We draw attention to how small changes in gas metrology impacts attainment and compliance with legal air quality standards.
Atmos. Chem. Phys. Discuss., 15, 19537-19551, doi:10.5194/acpd-15-19537-2015, 2015
Boundary layer new particle formation over East Antarctic sea ice – possible Hg driven nucleation?
Summary: An atmospheric new particle formation event that was observed in the pristine East Antarctic pack ice during a springtime voyage in 2012 is characterised in terms of formation and growth rates. Known nucleation mechanisms (e.g. those involving sulfate, iodine and organics) were unable to explain observations, however correlations with total gaseous mercury were found, leading to the suggestion of a possible mercury driven nucleation mechanism not previously described.
Atmos. Chem. Phys. Discuss., 15, 19477-19536, doi:10.5194/acpd-15-19477-2015, 2015
The contrasting roles of water and dust in controlling daily variations in radiative heating of the summertime Saharan Heat Low
Atmos. Chem. Phys. Discuss., 15, 19447-19476, doi:10.5194/acpd-15-19447-2015, 2015
Continuous measurements at the urban roadside in an Asian Megacity by Aerosol Chemical Speciation Monitor (ACSM): particulate matter characteristics during fall and winter seasons in Hong Kong
Summary: This study presents results of long-term submicron aerosol measurements in Hong Kong. The presented work covers fall and winter 2013. It serves to characterize aerosol in a densely-built up urban area of a typical Asian megacity with strong primary emission sources from vehicles and cooking and presents an in-depth analysis of distinct clean and heavily polluted time periods tied with meteorological data and other gas-phase species observed in the study period.
Atmos. Chem. Phys. Discuss., 15, 19405-19445, doi:10.5194/acpd-15-19405-2015, 2015
Aerosol dynamics within and above forest in relation to turbulent transport and dry deposition
Atmos. Chem. Phys. Discuss., 15, 19367-19403, doi:10.5194/acpd-15-19367-2015, 2015
Characterization of long-range transported Saharan dust at the Caribbean by dual-wavelength depolarization Raman lidar measurements
Summary: In June and July 2013 dual-wavelength lidar measurements were performed at Barbados to study long-range transported Saharan dust across the Atlantic Ocean, and to investigate transport-induced changes. In the focus our measurements are the intensive optical properties, the lidar ratio and the particle linear depolarization ratio. While the lidar ratio shows no differences compared to the values of fresh Saharan dust, the particle linear depolarization ratio shows slight differences.
Atmos. Chem. Phys. Discuss., 15, 19325-19366, doi:10.5194/acpd-15-19325-2015, 2015
Influence of tropical cyclones on tropospheric ozone: possible implication
Summary: Highlights of the present study : (1) First observational evidence of enhanced upper tropospheric ozone during cyclonic and sever cyclonic storms (2) Enhancement of surface ozone after ever cyclonic storms (3) Intrusion of stratospheric air into the troposphere
Atmos. Chem. Phys. Discuss., 15, 19305-19323, doi:10.5194/acpd-15-19305-2015, 2015
A new indictor on the impact of large-scale circulation on wintertime particulate matter pollution over China
Atmos. Chem. Phys. Discuss., 15, 19275-19304, doi:10.5194/acpd-15-19275-2015, 2015
Development of a high temporal–spatial resolution vehicle emission inventory based on NRT traffic data and its impact on air pollution in Beijing – Part 2: Impact of vehicle emission on urban air quality
Summary: 1. Chinese Unified Atmospheric Chemistry Environment (CUACE) model had good performance of pollutants concentration simulation. 2. CUACE simulation has been improved by using high temporal-spatial resolution vehicle emission inventory. 3. The mean vehicle emission contribution is 55.4% and 48.5% for NO2, while 5.4% and 10.5% for PM2.5 in July and December 2013, respectively.
Atmos. Chem. Phys. Discuss., 15, 19239-19273, doi:10.5194/acpd-15-19239-2015, 2015
Changes in chemical components of aerosol particles in different haze regions in China from 2006 to 2013 and contribution of meteorological factors
Summary: No obvious changes were found in annual mean concentrations of major chemical components and PM10 in 2013, relative to 2012. But wintertime mass were quite different; approximately 60% of the winter mass increase from 2012 to 2013 can be attributed to severe meteorological conditions in the HBP area, and mass of chemical components exhibited a decline during 2006 to 2010, and then a rise till 2013. Coal-combustion was still the largest anthropogenic source of aerosol pollution in 2013 in China.
Atmos. Chem. Phys. Discuss., 15, 19197-19238, doi:10.5194/acpd-15-19197-2015, 2015
Evaluation of the Australian Community Climate and Earth-System Simulator Chemistry-Climate Model
Atmos. Chem. Phys. Discuss., 15, 19161-19196, doi:10.5194/acpd-15-19161-2015, 2015
Can we explain the observed methane variability after the Mount Pinatubo eruption?
Summary: We quantify the processes responsible for methane growth rate variability in the period 1990 to 1995, a period with variations in climate and radiation due to the Pinatubo eruption. We find significant contributions from changes in the methane emission from wetlands, and in the methane removal by OH caused by stratospheric aerosols, by the decrease in temperature and water vapour, by stratospheric ozone depletion and by changes in emissions of CO and NMVOC.
Atmos. Chem. Phys. Discuss., 15, 19111-19160, doi:10.5194/acpd-15-19111-2015, 2015
Observed high-altitude warming and snow cover retreat over Tibet and the Himalayas enhanced by black carbon aerosols
Summary: We show that black carbon aerosol pollution is likely the dominating factor in causing the accelerated retreat of snow pack. The simulated snow fraction and surface albedo change at the surface, as well as the enhanced warming at higher elevations, are remarkably similar to observations. The fundamental reason for the model’s ability to simulate the observed trends is that in this study, we replace the model simulated black carbon forcing with one that is constrained by observations.
Atmos. Chem. Phys. Discuss., 15, 19079-19109, doi:10.5194/acpd-15-19079-2015, 2015
Spectral optical layer properties of cirrus from collocated airborne measurements – a feasibility study
Atmos. Chem. Phys. Discuss., 15, 19045-19077, doi:10.5194/acpd-15-19045-2015, 2015
Constraints on methane emissions in North America from future geostationary remote sensing measurements
Summary: This work provides new insight into the observational constraints provided by current low earth orbit (LEO) and future potential geostationary (GEO) satellite mission on methane emissions in North America. Using efficient numerical tools, the information content (error reductions, spatial resolution of the constraints) of methane inversions using different instrument configurations (TIR, SWIR and multi-spectral) was estimated at model grid scale resolution (0.5 degx0.7deg).
Atmos. Chem. Phys. Discuss., 15, 19017-19044, doi:10.5194/acpd-15-19017-2015, 2015
The impact of snow nitrate photolysis on boundary layer chemistry and the recycling and redistribution of reactive nitrogen across Antarctica in a global chemical transport model
Summary: A snowpack actinic flux parameterization and a nitrate photolysis scheme are incorporated into a global chemical transport model (GEOS-Chem). This novel modeling framework is used to examine the implications of snow nitrate photolysis for boundary layer chemistry, the recycling and redistribution of reactive nitrogen across Antarctica, and the preservation of nitrate in Antarctic ice cores.
Atmos. Chem. Phys. Discuss., 15, 18963-19015, doi:10.5194/acpd-15-18963-2015, 2015
Impacts of aviation fuel sulfur content on climate and human health
Summary: Using a coupled tropospheric chemistry-aerosol microphysics model this research paper investigates the effect of variations in aviation fuel sulfur content (FSC) on surface PM2.5 concentrations, increases in aviation-induced premature mortalities, low-level cloud condensation nuclei and radiative effect. When investigating the climatic impact of variations in FSC the ozone direct radiative effect, aerosol direct radiative effect and aerosol cloud albedo effect are quantified.
Atmos. Chem. Phys. Discuss., 15, 18921-18961, doi:10.5194/acpd-15-18921-2015, 2015
Impacts of Amazonia biomass burning aerosols assessed from short-range weather forecasts
Atmos. Chem. Phys. Discuss., 15, 18883-18919, doi:10.5194/acpd-15-18883-2015, 2015
Simulation of black carbon in snow and its climate impact in the Canadian Global Climate Model
Summary: A new parameterization of black carbon in snow in the Canadian Atmospheric Global Climate Model provides realistic simulations of radiative forcings. BC emissions and simulated BC concentrations in snow have changed substantially in recent decades. However, simulated impacts of changes in BC concentrations in snow from 1950-1959 to 2000-2009 on snow reflectivity and snow extent in the Northern Hemisphere are very small, with few regional exceptions, in contrast to results from earlier studies.
Atmos. Chem. Phys. Discuss., 15, 18839-18882, doi:10.5194/acpd-15-18839-2015, 2015
High-resolution inventory of technologies, activities, and emissions of coal-fired power plants in China from 1990 to 2010
Summary: This is the first study that emissions from China’s coal-fired power plants were estimated at unit level for a 20-yr period. This new emission inventory is constructed from a unit-based database compiled in this work, named the China coal-fired Power plant Emissions Database (CPED), which includes detailed information on the technologies, activity data, operation situation, emission factors, and locations of individual units.
Atmos. Chem. Phys. Discuss., 15, 18787-18837, doi:10.5194/acpd-15-18787-2015, 2015
Atmospheric polarimetric effects on GNSS Radio Occultations: the ROHP-PAZ field campaign
Atmos. Chem. Phys. Discuss., 15, 18747-18785, doi:10.5194/acpd-15-18747-2015, 2015
Advantages of city-scale emission inventory for urban air quality research and policy: the case of Nanjing, a typical industrial city in the Yangtze River Delta, China
Summary: A high-resolution emission inventory of air pollutants and CO2 for Nanjing, a typical city in eastern China, is developed incorporating the best available local information from onsite survey. The temporal and spatial distribution of the emissions and the correlation between specific species of the inventory are assessed by comparisons with observations and other inventories at larger spatial scale. The emission inventory provides a basis to consider the quality of instrumental observations.
Atmos. Chem. Phys. Discuss., 15, 18691-18746, doi:10.5194/acpd-15-18691-2015, 2015
Nucleation and growth of sub-3 nm particles in the polluted urban atmosphere of a megacity in China
Atmos. Chem. Phys. Discuss., 15, 18653-18690, doi:10.5194/acpd-15-18653-2015, 2015
Comparison of vertical aerosol extinction coefficients from in-situ and LIDAR measurements
Atmos. Chem. Phys. Discuss., 15, 18609-18651, doi:10.5194/acpd-15-18609-2015, 2015
The influence of synoptic weather regimes on UK air quality: regional model studies of tropospheric column NO2
Atmos. Chem. Phys. Discuss., 15, 18577-18607, doi:10.5194/acpd-15-18577-2015, 2015
New characteristics of submicron aerosols and factor analysis of combined organic and inorganic aerosol mass spectra during winter in Beijing
Atmos. Chem. Phys. Discuss., 15, 18537-18576, doi:10.5194/acpd-15-18537-2015, 2015
On the ability of RegCM4 regional climate model to simulate surface solar radiation patterns over Europe: an assessment using satellite-based observations
Summary: It is shown here that RegCM4 regional climate model simulates adequately surface solar radiation (SSR) over Europe but over/under-estimates significantly several parameters that determine the transmission of solar radiation in the atmosphere. The agreement between RegCM4 and satellite-based SSR observations is actually a result of the contradicting effect of these parameters. We suggest that there should be a reassessment of the way these parameters are represented within this and other models.
Atmos. Chem. Phys. Discuss., 15, 18487-18535, doi:10.5194/acpd-15-18487-2015, 2015
Impact of future land cover changes on HNO3 and O3 surface dry deposition
Summary: Dry deposition is a key component of surface-atmosphere exchange of compounds, acting as a sink for several chemical species and strongly driven by meteorological factors, chemical properties of the trace gas considered and land surface properties. The objective of our study is to investigate the impact of vegetation distribution change, which is still not very well quantified, on the dry deposition of key atmospheric species: ozone and nitric acid vapor.
Atmos. Chem. Phys. Discuss., 15, 18459-18485, doi:10.5194/acpd-15-18459-2015, 2015
Air quality and radiative impacts of Arctic shipping emissions in the summertime in northern Norway: from the local to the regional scale
Atmos. Chem. Phys. Discuss., 15, 18407-18457, doi:10.5194/acpd-15-18407-2015, 2015
Quantifying atmospheric nitrogen deposition through a nationwide monitoring network across China
Summary: The annual average concentrations (1.3-47.0µg N m-3) and dry plus wet deposition fluxes (2.9-75.2kg N ha-1 yr-1) of inorganic Nr species ranked by region as North China > Southeast China > Southwest China > Northeast China > Northwest China > the Tibetan Plateau or by land use as urban > rural > background sites, reflecting the impact of anthropogenic Nr emission. Average dry and wet N deposition fluxes were 18.5 and 19.3kg N ha-1 yr-1, respectively, across China.
Atmos. Chem. Phys. Discuss., 15, 18365-18405, doi:10.5194/acpd-15-18365-2015, 2015
The diurnal cycle of rainfall over New Guinea in convection-permitting WRF simulations
Summary: Our paper highlights the importance of terrain, coastal and convectively induced gravity waves in contributing to the diurnal cycle of rainfall over the Maritime Continent, especially the offshore precipitation maxima adjacent to linearly oriented coastlines. We find that days with offshore propagating systems are largely controlled by background conditions (more mid-tropospheric moisture, more CAPE and more low-level moisture flux convergence) as opposed to days without offshore propagation.
Atmos. Chem. Phys. Discuss., 15, 18327-18363, doi:10.5194/acpd-15-18327-2015, 2015
Enhanced internal gravity wave activity and breaking over the Northeastern Pacific/Eastern Asian region
Summary: In this study, we present a discovery of an internal gravity wave activity and breaking hotspot collocated with an area of anomalously low annual cycle amplitude and specific dynamics in the stratosphere over the Northeastern Pacific/Eastern Asia coastal region. The reasons, why this particular IGW activity hotspot was not discovered before nor the specific dynamics of this region was pointed out, are discussed together with possible consequences on the middle atmospheric dynamics and transport.
Atmos. Chem. Phys. Discuss., 15, 18285-18325, doi:10.5194/acpd-15-18285-2015, 2015
Fourteen months of on-line measurements of the non-refractory submicron aerosol at the Jungfraujoch (3580 m a.s.l.) – chemical composition, origins and organic aerosol sources
Summary: This manuscript presents the first long-term (14 months) and highly time resolved (10 min) measurements of NR-PM1 aerosol chemical composition at a high-altitude site (JFJ, Switzerland, 3580m asl). The elevated location allowed the investigation of free tropospheric aerosol year round. Total and relative mass loadings, diurnal variations as well as seasonal variations are discussed together with geographical origin, organic aerosol sources and the influence of the planetary boundary layer.
Atmos. Chem. Phys. Discuss., 15, 18225-18284, doi:10.5194/acpd-15-18225-2015, 2015
The origins of ice crystals measured in mixed phase clouds at High-Alpine site Jungfraujoch
Summary: The paper explores the microphysical structure of clouds at high-alpine measurement site Jungfraujoch, Switzerland. High concentrations of ice crystals were measured by a range of instruments. The presence of these high concentrations could not be explained through conventional understanding of ice formation processes in clouds and the possibility that the surface provides a significant source of ice crystals is investigated.
Atmos. Chem. Phys. Discuss., 15, 18181-18224, doi:10.5194/acpd-15-18181-2015, 2015
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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