Meteor radar quasi 2-day wave observations over 10 years at Collm (51.3° N, 13.0° E)
Summary: The quasi 2-day wave (QTDW), one of the most striking features in the mesosphere/lower thermosphere, is analyzed using meteor radar measurements at Collm (51°N, 13°E) during 2004-2014. The QTDW has periods lasting between 43 and 52h during strong summer bursts, and weaker enhancements are found during winter. A correlation between QTDW amplitudes and wind shear suggests baroclinic instability to be a likely forcing mechanism.
Atmos. Chem. Phys., 15, 9917-9927, doi:10.5194/acp-15-9917-2015, 2015
Consistent response of Indian summer monsoon to Middle East dust in observations and simulations
Summary: Satellite data show that Indian summer monsoon (ISM) rainfall is 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, associated with the development of an anomalous low-pressure system over the Iranian Plateau and the Arabian Sea due to dust-induced atmospheric heating.
Atmos. Chem. Phys., 15, 9897-9915, doi:10.5194/acp-15-9897-2015, 2015
Atmospheric chemistry of nitrogenous aerosols in northeastern Asia: biological sources and secondary formation
Atmos. Chem. Phys., 15, 9883-9896, doi:10.5194/acp-15-9883-2015, 2015
Observation of ozone enhancement in the lower troposphere over East Asia from a space-borne ultraviolet spectrometer
Summary: The lower tropospheric ozone distribution maps were first obtained from the recent retrieval products of the Ozone Monitoring Instrument (OMI) onboard the Earth Observing System (EOS) Aura satellite. We found significant enhancement of ozone in the lower troposphere over central and eastern China (CEC), with Shandong Province as its center, and most notable in June in any given year. Similar seasonal variations were observed throughout the 9-year OMI measurement period of 2005 to 2013.
Atmos. Chem. Phys., 15, 9865-9881, doi:10.5194/acp-15-9865-2015, 2015
Is there a solar signal in lower stratospheric water vapour?
Summary: A merged data set of HALOE and MIPAS lower stratospheric water vapour has been constructed. Multivariate linear regression shows that the merged time series can best be explained if a proxy for the 11-year solar cycle is considered. The amplitude of the solar cycle signal in water vapour is slightly higher than that which can be explained by the known solar cycle variation of cold-point temperatures.
Atmos. Chem. Phys., 15, 9851-9863, doi:10.5194/acp-15-9851-2015, 2015
Long-lived atmospheric trace gases measurements in flask samples from three stations in India
Summary: We present 5-year flask measurements (2007–2011) of greenhouse gases (GHGs) at three atmospheric stations in India. The results suggest significant sources of CO2, CH4, N2O, CO, and H2 over S and NE India, while SF6 sources are weak. The seasonal cycles for each species reflect the seasonality of sources/sinks and influences of the Indian monsoon circulations. The data show potential to infer regional patterns of GHG fluxes and atmospheric transport over this under-documented region.
Atmos. Chem. Phys., 15, 9819-9849, doi:10.5194/acp-15-9819-2015, 2015
Evaluating BC and NOx emission inventories for the Paris region from MEGAPOLI aircraft measurements
Atmos. Chem. Phys., 15, 9799-9818, doi:10.5194/acp-15-9799-2015, 2015
Trends in concentrations of atmospheric gaseous and particulate species in rural eastern Tennessee as related to primary emission reductions
Atmos. Chem. Phys., 15, 9781-9797, doi:10.5194/acp-15-9781-2015, 2015
Sensitivity of the recent methane budget to LMDz sub-grid-scale physical parameterizations
Atmos. Chem. Phys., 15, 9765-9780, doi:10.5194/acp-15-9765-2015, 2015
Comparing the CarbonTracker and TM5-4DVar data assimilation systems for CO2 surface flux inversions
Summary: We compare two different data assimilation systems for estimating sources and sinks of CO_2 from concentration measurements. The systems are CarbonTracker and TM5-4DVar, which have both been used in a number of scientific studies. We analyze the differences between both models as well as the sensitivity of the estimated sources and sinks to the observation coverage. The results provide a lower limit for the uncertainty of surface carbon fluxes with the current measurement network.
Atmos. Chem. Phys., 15, 9747-9763, doi:10.5194/acp-15-9747-2015, 2015
A mechanism for biologically induced iodine emissions from sea ice
Atmos. Chem. Phys., 15, 9731-9746, doi:10.5194/acp-15-9731-2015, 2015
Trajectory mapping of middle atmospheric water vapor by a mini network of NDACC instruments
Summary: We use water vapor profiles from ground-based microwave radiometers at five locations distributed over the Northern Hemisphere and operated in the frame of NDACC (Network for the Detection of Atmospheric Composition Change) to generate hemispheric water vapor maps based on the so-called trajectory mapping technique. The novelty is to show that a mini network of instruments is capable of providing information about the hemispheric distribution of water vapor under most conditions.
Atmos. Chem. Phys., 15, 9711-9730, doi:10.5194/acp-15-9711-2015, 2015
Seasonal and diurnal trends in black carbon properties and co-pollutants in Mexico City
Summary: Extended measurements of equivalent black carbon (eBC) derived from light absorption measurements have been 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., 15, 9693-9709, doi:10.5194/acp-15-9693-2015, 2015
Atmospheric black carbon and sulfate concentrations in Northeast Greenland
Summary: Aerosols particles reach via long-range transport the high Arctic and have significant impacts on Arctic climate. This article demonstrates the comparison of measured and modeled aerosol mass concentrations for black carbon and sulfate particles at a high Arctic site. Based on the findings aging processes during transport seem to prolong the lifetimes of the two species and favor the possibility for their transport to the high Arctic.
Atmos. Chem. Phys., 15, 9681-9692, doi:10.5194/acp-15-9681-2015, 2015
Interactions of bromine, chlorine, and iodine photochemistry during ozone depletions in Barrow, Alaska
Atmos. Chem. Phys., 15, 9651-9679, doi:10.5194/acp-15-9651-2015, 2015
Stratospheric ozone in boreal fire plumes – the 2013 smoke season over central Europe
Atmos. Chem. Phys., 15, 9631-9649, doi:10.5194/acp-15-9631-2015, 2015
Continental pollution in the western Mediterranean basin: vertical profiles of aerosol and trace gases measured over the sea during TRAQA 2012 and SAFMED 2013
Summary: Observations from this study indicate that continental pollution largely affects the atmospheric composition and structure of the western Mediterranean basin. Pollution plumes reach 3000-4000 m in altitude and present a very complex and highly stratified structure, characterized by fresh and aged layers both in the boundary layer and in the free troposphere. Also we report the observations of high levels of ultrafine particles over the basin, possibly linked to new particle formation events.
Atmos. Chem. Phys., 15, 9611-9630, doi:10.5194/acp-15-9611-2015, 2015
Climate extremes in multi-model simulations of stratospheric aerosol and marine cloud brightening climate engineering
Summary: Simulations conducted in the GeoMIP and IMPLICC model intercomparison studies for climate engineering by stratospheric sulfate injection and marine cloud brightening via sea salt are analysed and compared to the reference scenario RCP4.5. The focus is on extremes in surface temperature and precipitation. It is found that the extreme changes mostly follow the mean changes and that extremes are also in general well mitigated, except for in polar regions.
Atmos. Chem. Phys., 15, 9593-9610, doi:10.5194/acp-15-9593-2015, 2015
In situ, satellite measurement and model evidence on the dominant regional contribution to fine particulate matter levels in the Paris megacity
Summary: A detailed characterization of air quality in the Paris (France) agglomeration, a megacity, during two summer and winter intensive campaigns and from additional 1-year observations, revealed that about 70% of the fine particulate matter (PM) at urban background is transported into the megacity from upwind regions. Unexpectedly, a major part of organic PM is of modern origin (woodburning and cooking activities, secondary formation from biogenic VOC).
Atmos. Chem. Phys., 15, 9577-9591, doi:10.5194/acp-15-9577-2015, 2015
Assessment of crop yield losses in Punjab and Haryana using 2 years of continuous in situ ozone measurements
Summary: We use ozone measurements at a suburban site in Punjab to estimate ozone-related crop yield losses for wheat, rice, cotton and maize in Punjab and Haryana for the years 2011-2013. Crop production losses amount to 10.3-20.8 Mt yr-1 for wheat and 3.2-5.4 Mt yr-1 for rice, enough to feed 225-437 million of India’s poor. The lower limit for the ozone-related economic losses is 3.7-6.5 billion USD (Punjab and Haryana), while the upper limit amounts to 3.5-20% of Indian GDP (all of India).
Atmos. Chem. Phys., 15, 9555-9576, doi:10.5194/acp-15-9555-2015, 2015
Diurnal cycle of the dust instantaneous direct radiative forcing over the Arabian Peninsula
Summary: The radiative effect of dust over the Arabian Peninsula for different surfaces and for a range of optical depths is calculated and tested using satellite and ground-based observations.
Atmos. Chem. Phys., 15, 9537-9553, doi:10.5194/acp-15-9537-2015, 2015
Atmospheric isoprene ozonolysis: impacts of stabilised Criegee intermediate reactions with SO2, H2O and dimethyl sulfide
Summary: Stabilised Criegee intermediates (SCIs) are formed through alkene-ozone reactions, which occur throughout the atmospheric boundary layer. Recent direct laboratory studies have shown that SCI react rapidly with SO2, NO2 and other trace gases, affecting air quality and climate. We present experimental data from the EUPHORE atmospheric simulation chamber, in which we determine the effects of the ozonolysis of isoprene, on the oxidation of SO2 as a function of H2O and dimethyl sulfide concentration.
Atmos. Chem. Phys., 15, 9521-9536, doi:10.5194/acp-15-9521-2015, 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 (NW-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 seasons. 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., 15, 9501-9520, doi:10.5194/acp-15-9501-2015, 2015
Modelled and observed changes in aerosols and surface solar radiation over Europe between 1960 and 2009
Summary: We evaluate HadGEM3-UKCA over Europe for the period 1960-2009 against observations of aerosol mass and number, aerosol optical depth (AOD) and surface solar radiation (SSR). The model underestimates aerosol mass and number but is less biased if 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 > 3 Wm-2 from 1970 to 2009.
Atmos. Chem. Phys., 15, 9477-9500, doi:10.5194/acp-15-9477-2015, 2015
Observations of atmospheric mercury in China: a critical review
Atmos. Chem. Phys., 15, 9455-9476, doi:10.5194/acp-15-9455-2015, 2015
Investigation of post-depositional processing of nitrate in East Antarctic snow: isotopic constraints on photolytic loss, re-oxidation, and source inputs
Summary: We evaluate isotopic composition of NO3- in different environments across East Antarctica. At high snow accumulation sites, isotopic ratios are suggestive of preservation of NO3- deposition. At low accumulation sites, isotopes are sensitive to both the loss of NO3- due to photolysis and secondary formation of NO3- within the snow. The imprint of post-depositional alteration is not uniform with depth, making it difficult to predict the isotopic composition at depth from near-surface data alone.
Atmos. Chem. Phys., 15, 9435-9453, doi:10.5194/acp-15-9435-2015, 2015
Current model capabilities for simulating black carbon and sulfate concentrations in the Arctic atmosphere: a multi-model evaluation using a comprehensive measurement data set
Summary: The concentrations of sulfate, black carbon and other aerosols in the Arctic are characterized by high values in late winter and spring (so-called Arctic Haze) and low values in summer. Models have long been struggling to capture this seasonality. In this study, we evaluate sulfate and BC concentrations from different updated models and emissions against a comprehensive pan-Arctic measurement data set. We find that the models improved but still struggle to get the maximum concentrations.
Atmos. Chem. Phys., 15, 9413-9433, doi:10.5194/acp-15-9413-2015, 2015
NOx emission estimates during the 2014 Youth Olympic Games in Nanjing
Summary: We derived the NOx emissions from the OMI satellite observations. We find a NOx emission reduction of at least 25% during the Youth Olympic Games in Nanjing in 2014. The emission estimate algorithm has detected an emission reduction of 10% during the Chinese Spring Festival. This paper also shows that the observed concentrations and the derived emissions from space have different patterns that provide complimentary information.
Atmos. Chem. Phys., 15, 9399-9412, doi:10.5194/acp-15-9399-2015, 2015
Impacts of an unknown daytime HONO source on the mixing ratio and budget of HONO, and hydroxyl, hydroperoxyl, and organic peroxy radicals, in the coastal regions of China
Summary: High daytime HONO mixing ratios in experiments suggest that an unknown daytime HONO source (P unknown) could exist. P unknown≈19.60×NO2×J(NO2) was obtained using observed data from 13 field experiments across the globe, then coupled into the WRF-Chem model. Simulations indicated that elevated P unknown was found in the coastal regions of China; the additional HONO sources, especially the P unknown produced significant increases of radicals in the major cities, and accelerated the radical cycles.
Atmos. Chem. Phys., 15, 9381-9398, doi:10.5194/acp-15-9381-2015, 2015
Ash iron mobilization through physicochemical processing in volcanic eruption plumes: a numerical modeling approach
Summary: Iron released from volcanic ash can perturb the biogeochemical cycles in the ocean. However, knowing that the emitted ash from a volcano contains insoluble iron, what processes can solubilize the ash iron while it is airborne? To answer this question, a numerical model is developed in this study to simulate the gas-ash-aerosol interactions within the eruption plume. Results show that the dissolution of the ash mediated by halogen acids exert the key control on ash iron mobilization.
Atmos. Chem. Phys., 15, 9361-9379, doi:10.5194/acp-15-9361-2015, 2015
Regional-scale transport of air pollutants: impacts of Southern California emissions on Phoenix ground-level ozone concentrations
Summary: Emission sensitivity studies, using WRF-Chem at 1.3km that was validated by observations, indicate the Arizona (AZ) emissions dominate on daily maximum 8-hr average (DMA8) [O3] in Phoenix (PHX). Southern California (SoCal) emission contribute to DMA8 [O3] for the PHX from a few ppb to over 30 ppb. [O3] from SoCal and AZ emissions exhibits diurnal characteristics. Pollutants near the SoCal coasts are transported to PHX by local circulations with different mechanisms.
Atmos. Chem. Phys., 15, 9345-9360, doi:10.5194/acp-15-9345-2015, 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 to 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., 15, 9327-9343, doi:10.5194/acp-15-9327-2015, 2015
Particulate organic nitrates observed in an oil and natural gas production region during wintertime
Summary: Secondary organic aerosol affects both the environment and human health. We characterized the aerosol composition in Uintah Basin by measuring the concentration of nitrooxy group moiety which is produced through chemical interaction of volatile organic compounds and NOx emitted largely from local human activity. We found nitrooxy compounds to be a persistent, if not dominant, portion of fine aerosol mass. Similar results may be expected from emissions due to traffic in cities.
Atmos. Chem. Phys., 15, 9313-9325, doi:10.5194/acp-15-9313-2015, 2015
A new model of the global biogeochemical cycle of carbonyl sulfide – Part 2: Use of carbonyl sulfide to constrain gross primary productivity in current vegetation models
Atmos. Chem. Phys., 15, 9285-9312, doi:10.5194/acp-15-9285-2015, 2015
A method for merging nadir-sounding climate records, with an application to the global-mean stratospheric temperature data sets from SSU and AMSU
Summary: This is the first paper of its kind describing a method for merging the long-term satellite records of global stratospheric temperature from SSU and AMSU to yield a continuous data set from 1979 to present (and beyond). Since global-mean stratospheric temperature is close to radiative equilibrium, our "extended" SSU data set is an important climate record for the detection and attribution of anthropogenic influence.
Atmos. Chem. Phys., 15, 9271-9284, doi:10.5194/acp-15-9271-2015, 2015
Organic photolysis reactions in tropospheric aerosols: effect on secondary organic aerosol formation and lifetime
Summary: Our study combines process and global chemistry modeling to investigate the potential effect of gas- and particle-phase organic photolysis reactions on the formation and lifetime of secondary organic aerosols (SOAs). Photolysis of the oxidation intermediates that partition between gas and particle phases to form SOA is not included in 3D models. Our results suggest that exposure to UV light can suppress the formation of SOA or even lead to its substantial loss (comparable to wet deposition).
Atmos. Chem. Phys., 15, 9253-9269, doi:10.5194/acp-15-9253-2015, 2015
A comparison of measured HONO uptake and release with calculated source strengths in a heterogeneous forest environment
Summary: We measured near-surface (< 2m) profiles of HONO in a clearing and on a forest floor. Both HONO deposition and emissions were observed. By comparing three postulated sources to observed daytime emissions, we made several important findings: ● conversion of NO2 is mostly independent of light due to light saturation ● HONO emissions from a very acidic soil were low ● photolysis of adsorbed HNO3 could serve as HONO source based on empirical parameters but unlikely via the proposed reaction pathway.
Atmos. Chem. Phys., 15, 9237-9251, doi:10.5194/acp-15-9237-2015, 2015
Microphysical processing of aerosol particles in orographic clouds
Atmos. Chem. Phys., 15, 9217-9236, doi:10.5194/acp-15-9217-2015, 2015
Atmospheric new particle formation as a source of CCN in the eastern Mediterranean marine boundary layer
Summary: Cloud condensation nuclei (CCN) production associated with atmospheric new particle formation (NPF) is presented, and this is the first direct evidence of CCN production resulting from NPF in the eastern Mediterranean atmosphere. We show that condensation of both gaseous sulfuric acid and organic compounds from multiple sources leads to the rapid growth of nucleated particles. Sub-100nm particles were found to be substantially less hygroscopic than larger particles during the active NPF period.
Atmos. Chem. Phys., 15, 9203-9215, doi:10.5194/acp-15-9203-2015, 2015
A better understanding of hydroxyl radical photochemical sources in cloud waters collected at the puy de Dôme station – experimental versus modelled formation rates
Atmos. Chem. Phys., 15, 9191-9202, doi:10.5194/acp-15-9191-2015, 2015
Dust–air pollution dynamics over the eastern Mediterranean
Atmos. Chem. Phys., 15, 9173-9189, doi:10.5194/acp-15-9173-2015, 2015
Laboratory studies of collection efficiency of sub-micrometer aerosol particles by cloud droplets on a single-droplet basis
Summary: The collection between aerosol and a water droplet is an important mechanism for removing particles from the atmosphere, and has an influence on cloud dynamics, precipitation processes and cloud lifetime. In this experiment, the collection process was studied on a single-droplet basis, with atmospherically relevant conditions (droplet sizes, charges and flow). Collection efficiency values were found to be in agreement with previous experimental and theoretical studies.
Atmos. Chem. Phys., 15, 9159-9171, doi:10.5194/acp-15-9159-2015, 2015
Transport of Antarctic stratospheric strongly dehydrated air into the troposphere observed during the HALO-ESMVal campaign 2012
Atmos. Chem. Phys., 15, 9143-9158, doi:10.5194/acp-15-9143-2015, 2015
What is the limit of climate engineering by stratospheric injection of SO2?
Summary: The injection of sulfur dioxide is considered as an option for solar radiation management. We have calculated the effects of SO2 injections up to 100 Tg(S)/y. Our calculations show that the forcing efficiency of the injection decays exponentially. This result implies that SO2 injections in the order of 6 times Mt. Pinatubo eruptions per year are required to keep temperatures constant at that anticipated for 2020, whilst maintaining business as usual emission conditions.
Atmos. Chem. Phys., 15, 9129-9141, doi:10.5194/acp-15-9129-2015, 2015
Aqueous-phase oligomerization of methyl vinyl ketone through photooxidation – Part 2: Development of the chemical mechanism and atmospheric implications
Summary: A detailed chemical mechanism is developed based on laboratory studies that predicts the formation of high molecular weight compounds in the aqueous phase of atmospheric aerosol particles. Model simulations using this mechanism for atmospheric conditions show that these pathways are likely not a substantial source of particle mass, unless unidentified precursors for these compounds exist that were not taken into account so far and/or the solubility of oxygen in aerosol water is overestimated.
Atmos. Chem. Phys., 15, 9109-9127, doi:10.5194/acp-15-9109-2015, 2015
Effect of atmospheric aging on volatility and reactive oxygen species of biodiesel exhaust nano-particles
Summary: This study investigates the effects of biodiesel's chemical composition on the volatility and reactive oxygenate species of fresh and aged diesel particulate matter. Using a potential aerosol mass chamber, changes of volatility and reactive oxygenated species are studied. The study concludes that more saturated and more oxygenated diesel fuels can cause more volatile particles carrying more reactive oxygenated species whether before or after aging.
Atmos. Chem. Phys., 15, 9099-9108, doi:10.5194/acp-15-9099-2015, 2015
The ENSO signal in atmospheric composition fields: emission-driven versus dynamically induced changes
Atmos. Chem. Phys., 15, 9083-9097, doi:10.5194/acp-15-9083-2015, 2015
Three-dimensional dust aerosol distribution and extinction climatology over northern Africa simulated with the ALADIN numerical prediction model from 2006 to 2010
Summary: The seasonal cycle and optical properties of mineral dust aerosols in northern Africa were simulated for the period from 2006 to 2010 using the numerical atmospheric model ALADIN (Aire Limitée Adaptation dynamique Développement InterNational) coupled to the surface scheme SURFEX (SURFace EXternalisée). These simulations aim to quantify the dust emission and deposition and establish a three-dimensional dust aerosol distribution and extinction climatology over northern Africa.
Atmos. Chem. Phys., 15, 9063-9082, doi:10.5194/acp-15-9063-2015, 2015
Secondary organic aerosol formation from photochemical aging of light-duty gasoline vehicle exhausts in a smog chamber
Atmos. Chem. Phys., 15, 9049-9062, doi:10.5194/acp-15-9049-2015, 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., 15, 9031-9047, doi:10.5194/acp-15-9031-2015, 2015
An investigation of how radiation may cause accelerated rates of tropical cyclogenesis and diurnal cycles of convective activity
Atmos. Chem. Phys., 15, 9003-9029, doi:10.5194/acp-15-9003-2015, 2015
Concentrations and solubility of trace elements in fine particles at a mountain site, southern China: regional sources and cloud processing
Summary: Twelve trace elements in fine particles and clouds at a mountain site in southern China were investigated. Long-range transport contributed the most to element concentrations, whereas the YRD and the area around Mt. Lushan exhibited the highest element solubility. We demonstrated that cloud processing can enhance aerosol element solubility and increase sulfate concentration correspondingly, by irreversibly altering the morphology of metal particles in cloud droplet residues.
Atmos. Chem. Phys., 15, 8987-9002, doi:10.5194/acp-15-8987-2015, 2015
Hygroscopic and phase separation properties of ammonium sulfate/organics/water ternary solutions
Summary: This work investigates hygroscopic properties of internally mixed organic/inorganic aerosol particles. Aerosol particles containing organic and inorganic components can phase separate under certain relative humidity conditions, creating particles with an inorganic core and an organic shell. This paper explores whether water uptake from gaseous phase still occurs in such phase-separated systems. It finds that phase separation does not inhibit water uptake for the five systems that were studied.
Atmos. Chem. Phys., 15, 8975-8986, doi:10.5194/acp-15-8975-2015, 2015
Tropospheric ozone and its precursors from the urban to the global scale from air quality to short-lived climate forcer
Summary: Ozone holds a certain fascination in atmospheric science. It is ubiquitous in the atmosphere, central to tropospheric oxidation chemistry, and yet harmful to human and ecosystem health as well as being an important greenhouse gas. It is not emitted into the atmosphere but is a byproduct of the very oxidation chemistry it largely initiates. This review examines current understanding of the processes regulating tropospheric ozone at global to local scales from both measurements and models.
Atmos. Chem. Phys., 15, 8889-8973, doi:10.5194/acp-15-8889-2015, 2015
Examining the effects of anthropogenic emissions on isoprene-derived secondary organic aerosol formation during the 2013 Southern Oxidant and Aerosol Study (SOAS) at the Look Rock, Tennessee ground site
Summary: Isoprene epoxydiols (IEPOX) are major gas-phase products from the atmospheric oxidation of isoprene that yield secondary organic aerosol (SOA) by reactive uptake onto acidic sulfate aerosol. We report a substantial contribution of IEPOX-derived SOA to the total fine aerosol collected during summer. IEPOX-derived SOA measured by online and offline mass spectrometry techniques is correlated with acidic sulfate aerosol, demonstrating the critical role of anthropogenic emissions in its formation.
Atmos. Chem. Phys., 15, 8871-8888, doi:10.5194/acp-15-8871-2015, 2015
Chemical composition, microstructure, and hygroscopic properties of aerosol particles at the Zotino Tall Tower Observatory (ZOTTO), Siberia, during a summer campaign
Summary: Our manuscript describes the hygroscopic properties of accumulation- and coarse-mode aerosol particles sampled at the ZOTTO in central Siberia (61º N, 89º E). The hygroscopic growth measurements were supplemented with chemical analyses of the samples. In addition, the microstructure and chemical composition of aerosol particles were analyzed by x-ray micro-spectroscopy (STXM-NEXAFS) and transmission electron microscopy (TEM).
Atmos. Chem. Phys., 15, 8847-8869, doi:10.5194/acp-15-8847-2015, 2015
New fire diurnal cycle characterizations to improve fire radiative energy assessments made from MODIS observations
Summary: The polar orbiting MODIS instruments provide four daily observations of the fire diurnal cycle, resulting in erroneous fire radiative energy (FRE) estimates. Using geostationary SEVIRI data, we explore the fire diurnal cycle and its drivers for Africa to develop a new method to estimate global FRE in near real-time using MODIS. The fire diurnal cycle varied with climate and vegetation type, and including information on the fire diurnal cycle in the model significantly improved the FRE estimates.
Atmos. Chem. Phys., 15, 8831-8846, doi:10.5194/acp-15-8831-2015, 2015
The anthropogenic contribution to atmospheric black carbon concentrations in southern Africa: a WRF-Chem modeling study
Summary: The numerical model WRF-Chem is used to estimate the contribution of anthropogenic emissions to BC, aerosol optical depth and atmospheric heating rates over southern Africa. An evaluation of the model with observational data including long-term BC measurements shows that the basic meteorology is reproduced reasonably well but simulated near-surface BC concentrations are underestimated by up to 50%. It is found that up to 100% of the BC in highly industrialized regions is of anthropogenic origin.
Atmos. Chem. Phys., 15, 8809-8830, doi:10.5194/acp-15-8809-2015, 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., 15, 8795-8808, doi:10.5194/acp-15-8795-2015, 2015
Seasonal variation of secondary organic aerosol tracers in Central Tibetan Plateau
Summary: 1) Seasonal trends of SOA tracers and origins were studied in the remote TP for the first time. 2) Seasonal variation of isoprene SOA tracers was mainly influenced by emission. 3) Due to the transport of air pollutants from the Indian subcontinent, aromatics SOA tracer presented relatively higher levels in the summer and elevated mass fractions in the winter. 4) Biogenic SOC dominated over anthropogenic SOC in the remote TP.
Atmos. Chem. Phys., 15, 8781-8793, doi:10.5194/acp-15-8781-2015, 2015
Source attribution and process analysis for atmospheric mercury in eastern China simulated by CMAQ-Hg
Summary: This study estimated the contributions to mercury concentration and deposition in easter China from seven categories of emission sources by CMAQ-Hg. Also, this study focuses on diagnostic and process analyses for atmospheric mercury pollution formation and on identification of the dominant atmospheric processes for mercury.
Atmos. Chem. Phys., 15, 8767-8779, doi:10.5194/acp-15-8767-2015, 2015
Trace metal characterization of aerosol particles and cloud water during HCCT 2010
Atmos. Chem. Phys., 15, 8751-8765, doi:10.5194/acp-15-8751-2015, 2015
Contrail life cycle and properties from 1 year of MSG/SEVIRI rapid-scan images
Atmos. Chem. Phys., 15, 8739-8749, doi:10.5194/acp-15-8739-2015, 2015
Prognostic precipitation with three liquid water classes in the ECHAM5–HAM GCM
Summary: We have introduced prognostic precipitation for both liquid (drizzle and rain) and solid (snow) phase precipitation into the global circulation model ECHAM5-HAM. This has a significant effect on the clouds and the parameterized collection rates, also reducing the sensitivity of the liquid water path to the anthropogenic aerosol forcing. Altogether the results suggest that the treatment of precipitation in global circulation models has a significant influence on the phase and lifetime of clouds.
Atmos. Chem. Phys., 15, 8717-8738, doi:10.5194/acp-15-8717-2015, 2015
Impact of the 2009 major sudden stratospheric warming on the composition of the stratosphere
Summary: A remarkable major stratospheric sudden warming during the boreal winter 2008/09 is studied with the Chemical Lagrangian Model of the Stratosphere (CLaMS). We investigate how mixing triggered by this event correlates the wave forcing and how transport and mixing affect the composition of the whole stratosphere in the Northern Hemisphere, by using the tracer-tracer correlation technique.
Atmos. Chem. Phys., 15, 8695-8715, doi:10.5194/acp-15-8695-2015, 2015
On the link between hygroscopicity, volatility, and oxidation state of ambient and water-soluble aerosols in the southeastern United States
Summary: The hygroscopicity of SE US aerosol is mostly water-soluble, with a hygroscopicity that is insensitive to partial volatilization in a thermodenuder. The most and least oxidized components of the aerosol are the most hygroscopic of organic constituents. No clear relationship was found between organic aerosol hygroscopicity and oxygen-to-carbon ratio. The aerosol factors covary in a way that induces the observed diurnal invariance in total organic hygroscopicity.
Atmos. Chem. Phys., 15, 8679-8694, doi:10.5194/acp-15-8679-2015, 2015
Patterns in atmospheric carbonaceous aerosols in China: emission estimates and observed concentrations
Summary: We present an emission inventory with quantified uncertainties of organic carbon (OC) and elemental carbon (EC) in China. New emission factors from local measurements lead to lower OC emissions than previous studies. We use ground observations to test the levels, trends, and spatial pattern of the emissions. The improvement over prior inventories is indicated by inter-annual comparison and correlation analysis between emissions and observations. Sources with high primary OC/EC are underestimate.
Atmos. Chem. Phys., 15, 8657-8678, doi:10.5194/acp-15-8657-2015, 2015
Contribution from biogenic organic compounds to particle growth during the 2010 BEACHON-ROCS campaign in a Colorado temperate needleleaf forest
Atmos. Chem. Phys., 15, 8643-8656, doi:10.5194/acp-15-8643-2015, 2015
Improvement of climate predictions and reduction of their uncertainties using learning algorithms
Atmos. Chem. Phys., 15, 8631-8641, doi:10.5194/acp-15-8631-2015, 2015
On the use of satellite-derived CH4 : CO2 columns in a joint inversion of CH4 and CO2 fluxes
Summary: This study attempts to determine the feasibility of a new assimilation method of satellite measurements of CH4 and CO2 for optimization of their surface fluxes in a synthetic environment. Instead of their absolute concentrations, we assimilate the ratios of their concentrations (CH4/CO2) in our inversion. Doing so helps us to reduce the effect of atmospheric scattering on the measurements in our system. However, assimilation of the ratios makes the inversion non-linear.
Atmos. Chem. Phys., 15, 8615-8629, doi:10.5194/acp-15-8615-2015, 2015
Effects of urban land expansion on the regional meteorology and air quality of eastern China
Summary: We examine the responses of a range of meteorological and air quality indicators to the expansion of urban land using WRF/Chem. Sensitivity studies indicate that the responses of pollutant concentrations to the spatial extent of urbanization are linear near the surface but nonlinear at higher altitudes. The results of process analysis demonstrate that urban heat island circulation and a deeper boundary layer with stronger turbulent intensities play a significant role in relocating pollutants.
Atmos. Chem. Phys., 15, 8597-8614, doi:10.5194/acp-15-8597-2015, 2015
Uncertainties in global aerosols and climate effects due to biofuel emissions
Summary: We examine sensitivities in aerosol concentration and climate effects from biofuel combustion emissions. We find a strong sensitivity in the overall sign and magnitude of the direct radiative effect and cloud-albedo indirect effect due to uncertainties regarding emissions size distribution, composition, mass, and optical mixing state. This uncertainty limits our ability to evaluate black carbon mitigation strategies to counter warming effects from greenhouse gases.
Atmos. Chem. Phys., 15, 8577-8596, doi:10.5194/acp-15-8577-2015, 2015
Relationships between photosynthesis and formaldehyde as a probe of isoprene emission
Summary: We apply two global observational data sets, gross primary productivity (GPP) and tropospheric formaldehyde column variability (HCHOv), to probe isoprene emission variability on large spatiotemporal scales. GPP and HCHOv are decoupled or weakly anticorrelated in regions and seasons when isoprene emission is high. Isoprene emission models that include soil moisture dependence demonstrate greater skill in reproducing observed seasonal GPP-HCHOv correlations in the southeast US and the Amazon.
Atmos. Chem. Phys., 15, 8559-8576, doi:10.5194/acp-15-8559-2015, 2015