scholarly journals Aerosol ageing in an urban plume – implication for climate

2011 ◽  
Vol 11 (12) ◽  
pp. 5897-5915 ◽  
Author(s):  
P. Roldin ◽  
E. Swietlicki ◽  
A. Massling ◽  
A. Kristensson ◽  
J. Löndahl ◽  
...  
Keyword(s):  
Radiative Forcing ◽  
Particle Number ◽  
Particulate Emissions ◽  
Aerosol Formation ◽  
Aerosol Dynamics ◽  
Cloud Properties ◽  
Total Particle ◽  
Physical Particle ◽  
Urban Plume ◽  
Phase Chemistry

Abstract. The climate effects downwind of an urban area resulting from gaseous and particulate emissions within the city are as yet inadequately quantified. The aim of this work was to estimate these effects for Malmö city in southern Sweden (population 280 000). The chemical and physical particle properties were simulated with a model for Aerosol Dynamics, gas phase CHEMistry and radiative transfer calculations (ADCHEM) following the trajectory movement from upwind of Malmö, through the urban background environment and finally tens and hundreds of kilometers downwind of Malmö. The model results were evaluated using measurements of the particle number size distribution and chemical composition. The total particle number concentration 50 km (~ 3 h) downwind, in the center of the Malmö plume, is about 3700 cm−3 of which the Malmö contribution is roughly 30%. Condensation of nitric acid, ammonium and to a smaller extent oxidized organic compounds formed from the emissions in Malmö increases the secondary aerosol formation with a maximum of 0.7–0.8 μg m−3 6 to 18 h downwind of Malmö. The secondary mass contribution dominates over the primary soot contribution from Malmö already 3 to 4 h downwind of the emission sources and contributes to an enhanced total surface direct or indirect aerosol shortwave radiative forcing in the center of the urban plume ranging from −0.3 to −3.3 W m−2 depending on the distance from Malmö, and the specific cloud properties.

scholarly journals Aerosol ageing in an urban plume – implications for climate and health

2010 ◽  
Vol 10 (8) ◽  
pp. 18731-18780 ◽  
Author(s):  
P. Roldin ◽  
E. Swietlicki ◽  
A. Massling ◽  
A. Kristensson ◽  
J. Löndahl ◽  
...  
Keyword(s):  
Radiative Forcing ◽  
Particle Number ◽  
Particulate Emissions ◽  
Aerosol Formation ◽  
Aerosol Dynamics ◽  
Cloud Properties ◽  
Total Particle ◽  
Physical Particle ◽  
Climate And Health ◽  
Urban Plume

Abstract. The climate and health effects downwind of an urban area resulting from gaseous and particulate emissions within the city are as yet inadequately quantified. The aim of this work was to estimate these effects for Malmö city in Southern Sweden (population 280 000). The chemical and physical particle properties were simulated with a model for Aerosol Dynamics, gas phase CHEMistry and radiative transfer calculations (ADCHEM) following the trajectory movement from upwind Malmö, through the urban background environment and finally tens and hundreds of kilometers downwind Malmö. The model results were validated with measurements of the particle number size distribution and chemical composition. The total particle number concentration 50 km (~3 h) downwind in the center of the Malmö plume is about 3800 cm−3 and the Malmö contribution is roughly 35%. Condensation of nitric acid, ammonium and to a smaller extent oxidized organic compounds formed from the emissions in Malmö increases the secondary aerosol formation with a maximum of 0.6–0.7 μg/m3 6 to 18 h downwind of Malmö. The secondary mass contribution dominates over the primary soot contribution from Malmö already 2 to 3 h after the emissions and gives an enhanced total top of the atmosphere direct or indirect aerosol shortwave radiative forcing in the center of the urban plume ranging from −0.3 to −2.3 W m−2 depending on the distance from Malmö, and the cloud properties. It also gives an increased respiratory tract deposited mass dose, which increases with the distance downwind Malmö.

scholarly journals Annual cycle of Antarctic baseline aerosol: controlled by photooxidation-limited aerosol formation

2014 ◽  
Vol 14 (6) ◽  
pp. 3083-3093 ◽  
Author(s):  
M. Fiebig ◽  
D. Hirdman ◽  
C. R. Lunder ◽  
J. A. Ogren ◽  
S. Solberg ◽  
...  
Keyword(s):  
Annual Cycle ◽  
Particle Number ◽  
Climate Models ◽  
Aerosol Formation ◽  
Particle Volume ◽  
Transport Pathway ◽  
Air Masses ◽  
Total Particle ◽  
The Antarctic ◽  
Aerosol Properties

Abstract. This article investigates the annual cycle observed in the Antarctic baseline aerosol scattering coefficient, total particle number concentration, and particle number size distribution (PNSD), as measured at Troll Atmospheric Observatory. Mie theory shows that the annual cycles in microphysical and optical aerosol properties have a common cause. By comparison with observations at other Antarctic stations, it is shown that the annual cycle is not a local phenomenon, but common to central Antarctic baseline air masses. Observations of ground-level ozone at Troll as well as backward plume calculations for the air masses arriving at Troll demonstrate that the baseline air masses originate from the free troposphere and lower stratosphere region, and descend over the central Antarctic continent. The Antarctic summer PNSD is dominated by particles with diameters <100 nm recently formed from the gas-phase despite the absence of external sources of condensible gases. The total particle volume in Antarctic baseline aerosol is linearly correlated with the integral insolation the aerosol received on its transport pathway, and the photooxidative production of particle volume is mostly limited by photooxidative capacity, not availability of aerosol precursor gases. The photooxidative particle volume formation rate in central Antarctic baseline air is quantified to 207 ± 4 μm3/(MJ m). Further research is proposed to investigate the applicability of this number to other atmospheric reservoirs, and to use the observed annual cycle in Antarctic baseline aerosol properties as a benchmark for the representation of natural atmospheric aerosol processes in climate models.

scholarly journals Development and evaluation of the aerosol dynamics and gas phase chemistry model ADCHEM

2011 ◽  
Vol 11 (12) ◽  
pp. 5867-5896 ◽  
Author(s):  
P. Roldin ◽  
E. Swietlicki ◽  
G. Schurgers ◽  
A. Arneth ◽  
K. E. J. Lehtinen ◽  
...  
Keyword(s):  
Gas Phase ◽  
Size Structure ◽  
Particle Phase ◽  
Organic Mass ◽  
Product Model ◽  
Aerosol Dynamics ◽  
Gas Phase Chemistry ◽  
Urban Plume ◽  
Phase Chemistry ◽  
Urban Plumes

Abstract. The aim of this work was to develop a model suited for detailed studies of aerosol dynamics, gas and particle phase chemistry within urban plumes, from local scale (1 × 1 km2) to regional scale. This article describes and evaluates the trajectory model for Aerosol Dynamics, gas and particle phase CHEMistry and radiative transfer (ADCHEM). The model treats both vertical and horizontal dispersion perpendicular to an air mass trajectory (2-space dimensions). The Lagrangian approach enables a more detailed representation of the aerosol dynamics, gas and particle phase chemistry and a finer spatial and temporal resolution compared to that of available regional 3D-CTMs. These features make it among others well suited for urban plume studies. The aerosol dynamics model includes Brownian coagulation, dry deposition, wet deposition, in-cloud processing, condensation, evaporation, primary particle emissions and homogeneous nucleation. The organic mass partitioning was either modeled with a 2-dimensional volatility basis set (2D-VBS) or with the traditional two-product model approach. In ADCHEM these models consider the diffusion limited and particle size dependent condensation and evaporation of 110 and 40 different organic compounds respectively. The gas phase chemistry model calculates the gas phase concentrations of 61 different species, using 130 different chemical reactions. Daily isoprene and monoterpene emissions from European forests were simulated separately with the vegetation model LPJ-GUESS, and included as input to ADCHEM. ADCHEM was used to simulate the ageing of the urban plumes from the city of Malmö in southern Sweden (280 000 inhabitants). Several sensitivity tests were performed concerning the number of size bins, size structure method, aerosol dynamic processes, vertical and horizontal mixing, coupled or uncoupled condensation and the secondary organic aerosol formation. The simulations show that the full-stationary size structure gives accurate results with little numerical diffusion when more than 50 size bins are used between 1.5 and 2500 nm, while the moving-center method is preferable when only a few size bins are selected. The particle number size distribution in the center of the urban plume from Malmö was mainly affected by dry deposition, coagulation and vertical dilution. The modeled PM2.5 mass was dominated by organic material, nitrate, sulfate and ammonium. If the condensation of HNO3 and NH3 was treated as a coupled process (pH independent) the model gave lower nitrate PM2.5 mass than if considering uncoupled condensation. Although the time of ageing from that SOA precursors are emitted until condensable products are formed is substantially different with the 2D-VBS and two product model, the models gave similar total organic mass concentrations.

scholarly journals Description and evaluation of the community aerosol dynamics model MAFOR v2.0

2021 ◽  
Author(s):  
Matthias Karl ◽  
Liisa Pirjola ◽  
Tiia Grönholm ◽  
Mona Kurppa ◽  
Srinivasan Anand ◽  
...  
Keyword(s):  
Street Canyon ◽  
Ultrafine Particles ◽  
Particle Number ◽  
Numerical Models ◽  
Operator Splitting ◽  
Aerosol Formation ◽  
Dynamics Model ◽  
Aerosol Dynamics ◽  
Model Version ◽  
Consistent Treatment

Abstract. Numerical models are needed for evaluating aerosol processes in the atmosphere in state-of-the-art chemical transport models, urban-scale dispersion models and climatic models. This article describes a publicly available aerosol dynamics model MAFOR (Multicomponent Aerosol FORmation model; version 2.0); we address the main structure of the model, including the types of operation and the treatments of the aerosol processes. The main advantage of MAFOR v2.0 is the consistent treatment of both the mass- and number-based concentrations of particulate matter. An evaluation of the model is also presented, against a high-resolution observational dataset in a street canyon located in the centre of Helsinki (Finland) during an afternoon traffic rush hour on 13 December 2010. The experimental data included measurements at different locations in the street canyon of ultrafine particles, black carbon, and fine particulate mass PM1. This evaluation has also included an intercomparison with the corresponding predictions of two other prominent aerosol dynamics models, AEROFOR and SALSA. All three models fairly well simulated the decrease of the measured total particle number concentrations with increasing distance from the vehicular emission source. The MAFOR model reproduced the evolution of the observed particle number size distributions more accurately than the other two models. The MAFOR model also predicted the variation of the concentration of PM1 better than the SALSA model. We also analysed the relative importance of various aerosol processes based on the predictions of the three models. As expected, atmospheric dilution dominated over other processes; dry deposition was the second most significant process. Numerical sensitivity tests with the MAFOR model revealed that the uncertainties associated with the properties of the condensing organic vapours affected only the size range of particles smaller than 10 nm in diameter. These uncertainties do not therefore affect significantly the predictions of the whole of the number size distribution and the total number concentration. The MAFOR model version 2 is well documented and versatile to use, providing a range of alternative parametrizations for various aerosol processes. The model includes an efficient numerical integration of particle number and mass concentrations, an operator-splitting of processes, and the use of a fixed sectional method. The model could be used as a module in various atmospheric and climatic models.

scholarly journals Reviews and syntheses: Marine biogenic aerosols and the ecophysiology of coral reefs

2019 ◽  
Author(s):  
Rebecca Jackson ◽  
Albert Gabric ◽  
Roger Cropp ◽  
Matthew Woodhouse
Keyword(s):  
Climate Change ◽  
Coral Reefs ◽  
Social Services ◽  
Radiative Forcing ◽  
Marine Boundary Layer ◽  
Global Climate ◽  
Aerosol Formation ◽  
Radiative Balance ◽  
Cloud Properties

Abstract. Coral reefs are being threatened by global climate change, with ocean warming and acidification, compounded by declining water quality in many coastal systems, adversely affecting coral health and cover. This is of great concern as coral reefs provide numerous ecosystem, economic and social services. Corals are also recognized as being amongst the strongest individual sources of natural atmospheric sulfur, through stress-induced emissions of dimethylsulfide (DMS). In the clean marine boundary layer, biogenic sulfates contribute to new aerosol formation and the growth of existing particles, with important implications for the radiative balance. Evidence suggests that DMS is not only directly involved in the coral stress response, alleviating oxidative stress, but may create an ocean thermostat which suppresses sea surface temperature (SST) through changes to aerosol and cloud properties. This review provides a summary of the current major threats facing coral reefs and describes the role of dimethylated sulfur compounds in coral physiology and climate. The role of coral reefs as a source of climatically important compounds is an emerging topic of research however, the window of opportunity to understand the complex biogeophysical processes involved is closing with ongoing degradation of the world's coral reefs. The greatest uncertainty in our estimates of radiative forcing and climate change are derived from natural aerosol sources, such as marine DMS, which constitutes the largest flux of oceanic reduced sulfur to the atmosphere. Gaining a better understanding of the role of coral reef DMS emissions is crucial to predicting the future climate of our planet.

scholarly journals Aerosol dynamics in the Copenhagen urban plume during regional transport

2010 ◽  
Vol 10 (4) ◽  
pp. 8553-8594 ◽  
Author(s):  
F. Wang ◽  
P. Roldin ◽  
A. Massling ◽  
A. Kristensson ◽  
E. Swietlicki ◽  
...  
Keyword(s):  
Satisfactory Agreement ◽  
Particle Number ◽  
Meteorological Data ◽  
Atmospheric Dispersion ◽  
Emission Factors ◽  
Anthropogenic Sources ◽  
Minor Role ◽  
Size Distributions ◽  
Aerosol Dynamics ◽  
Urban Plume

Abstract. Aerosol particles in the submicrometer size range (PM1) have serious impacts on human health and climate. This work aims at studying the processes relevant for physical particle properties in and downwind Copenhagen and evaluating the capability of a detailed aerosol dynamics and chemistry model (ADCHEM) to describe the submicrometer aerosol dynamics in a complex urbanized region, subjected to a variety of important anthropogenic sources. The study area is the Oresund Region with Copenhagen (about 1.8 million people) as the major city, including the strait separating Denmark and Sweden with intense ship traffic. Modeled aerosol particle number size distributions and NOx concentrations are evaluated against ground-based measurements from two stations in the Copenhagen area in Denmark and one station in southern Sweden. The measured and modeled increments in NOx concentrations from rural background to the urban area showed satisfactory agreement, indicating that the estimated NOx emissions and modeled atmospheric dispersion are reasonable. For three out of five case studies, the modeled particle number concentrations and size distributions are in satisfactory agreement with the measurements at all stations along the trajectories. For the remaining cases the model significantly underestimates the particle number concentration over Copenhagen, but reaches acceptable agreement with the measurements at the downwind background station in Sweden. The major causes for this were identified as being the lack of spatial resolution in the meteorological data in describing boundary layer mixing heights and the uncertainty in the exact air mass trajectory path over Copenhagen. In addition, particle emission factors may also have been too low. It was shown that aerosol dynamics play a minor role from upwind to urban background, but are important 1–2 h downwind the city. Real-world size-resolved traffic number emission factors which take into account the initial ageing in the street canyon can be used to model traffic emissions in urban plume studies.

scholarly journals Decreasing particle number concentrations in a warming atmosphere and implications

2012 ◽  
Vol 12 (5) ◽  
pp. 2399-2408 ◽  
Author(s):  
F. Yu ◽  
G. Luo ◽  
R. P. Turco ◽  
J. A. Ogren ◽  
R. M. Yantosca
Keyword(s):  
Radiative Forcing ◽  
Particle Number ◽  
Feedback Mechanism ◽  
Aerosol Formation ◽  
Feedback Process ◽  
Key Factor ◽  
Remote Sites ◽  
Microphysical Processes ◽  
Earth’S Climate

Abstract. New particle formation contributes significantly to the number concentration of condensation nuclei (CN) as well as cloud CN (CCN), a key factor determining aerosol indirect radiative forcing of the climate system. Using a physics-based nucleation mechanism that is consistent with a range of field observations of aerosol formation, it is shown that projected increases in global temperatures could significantly inhibit new particle, and CCN, formation rates worldwide. An analysis of CN concentrations observed at four NOAA ESRL/GMD baseline stations since the 1970s and two other sites since 1990s reveals long-term decreasing trends that are consistent in sign with, but are larger in magnitude than, the predicted temperature effects. The possible reasons for larger observed long-term CN reductions at remote sites are discussed. The combined effects of rising temperatures on aerosol nucleation rates and other chemical and microphysical processes may imply substantial decreases in future tropospheric particle abundances associated with global warming, delineating a potentially significant feedback mechanism that increases Earth's climate sensitivity to greenhouse gas emissions. Further research is needed to quantify the magnitude of such a feedback process.

scholarly journals Decreasing particle number concentrations in a warming atmosphere and implications

2011 ◽  
Vol 11 (10) ◽  
pp. 27913-27936
Author(s):  
F. Yu ◽  
G. Luo ◽  
R. P. Turco ◽  
J. A. Ogren ◽  
R. M. Yantosca
Keyword(s):  
Radiative Forcing ◽  
Particle Number ◽  
Feedback Mechanism ◽  
Nucleation Mechanism ◽  
Aerosol Formation ◽  
Feedback Process ◽  
Key Factor ◽  
Remote Sites ◽  
Earth’S Climate

Abstract. New particle formation contributes significantly to the number concentration of condensation nuclei (CN) as well as cloud CN (CCN), a key factor determining aerosol indirect radiative forcing of the climate system. Using a physics-based nucleation mechanism that is consistent with a range of field observations of aerosol formation, it is shown that projected increases in global temperatures could significantly inhibit new particle, and CCN, formation rates worldwide. An analysis of CN concentrations observed at four NOAA ESRL/GMD baseline stations since the 1970s and two other sites since 1990s reveals long-term decreasing trends consistent with these predictions. The analysis also suggests, owing to larger observed CN reductions at remote sites than can be explained by the basic nucleation mechanism, that dimethylsulphide (DMS) emissions may be decreasing worldwide with increasing global temperatures, implying a positive DMS-based cloud feedback forcing of the climate ("CLAW"). The combined effects of rising temperatures on aerosol nucleation rates, and possibly on DMS emissions, may imply substantial decreases in future tropospheric particle abundances associated with global warming, delineating a potentially significant feedback mechanism that increases Earth's climate sensitivity to greenhouse gas emissions. Further research is needed to quantify the magnitude of such a feedback process.

scholarly journals Modelling the contribution of biogenic VOCs to new particle formation in the Jülich plant atmosphere chamber

2014 ◽  
Vol 14 (20) ◽  
pp. 27973-28018 ◽  
Author(s):  
L. Liao ◽  
M. Dal Maso ◽  
D. Mogensen ◽  
P. Roldin ◽  
A. Rusanen ◽  
...  
Keyword(s):  
Organic Compounds ◽  
Particle Number ◽  
Particle Formation ◽  
Oxidation Products ◽  
New Particle Formation ◽  
Particle Volume ◽  
Aerosol Dynamics ◽  
Total Particle Number ◽  
Total Particle ◽  
Air Chemistry

Abstract. We used the MALTE-BOX model including near-explicit air chemistry and detailed aerosol dynamics to study the mechanisms of observed new particle formation events in the Jülich Plant Atmosphere Chamber. The modelled and measured H2SO4 (sulfuric acid) concentrations agreed within a factor of two. The modelled total monoterpene concentration was in line with PTR-MS observations, and we provided the distributions of individual isomers of terpenes, when no measurements were available. The aerosol dynamic results supported the hypothesis that H2SO4 is one of the critical compounds in the nucleation process. However, compared to kinetic H2SO4 nucleation, nucleation involving OH oxidation products of monoterpenes showed a better agreement with the measurements, with R2 up to 0.97 between modelled and measured total particle number concentrations. The nucleation coefficient for kinetic H2SO4 nucleation was 2.1 × 10−11 cm3 s−1, while the organic nucleation coefficient was 9.0 × 10−14 cm3 s−1. We classified the VOC oxidation products into two sub-groups including extremely low-volatility organic compounds (ELVOCs) and semi-volatile organic compounds (SVOCs). These ELVOCs and SVOCs contributed approximately equally to the particle volume production, whereas only ELVOCs made the smallest particles to grow in size. The model simulations revealed that the chamber walls constitute a major net sink of SVOCs on the first experiment day. However, the net wall SVOC uptake was gradually reduced because of SVOC desorption during the following days. Thus, in order to capture the observed temporal evolution of the particle number size distribution, the model needs to consider reversible gas-wall partitioning.

scholarly journals Annual cycle of Antarctic baseline aerosol: controlled by photooxidation-limited aerosol formation

2013 ◽  
Vol 13 (9) ◽  
pp. 23057-23088
Author(s):  
M. Fiebig ◽  
D. Hirdman ◽  
C. R. Lunder ◽  
J. A. Ogren ◽  
S. Solberg ◽  
...  
Keyword(s):  
Annual Cycle ◽  
Particle Number ◽  
Climate Models ◽  
Aerosol Formation ◽  
Particle Volume ◽  
Transport Pathway ◽  
Air Masses ◽  
Total Particle ◽  
The Antarctic ◽  
Aerosol Properties

Abstract. This article investigates the annual cycle observed in the Antarctic baseline aerosol scattering coefficient, total particle number concentration, and particle number size distribution (PNSD) as measured at Troll Atmospheric Observatory. Mie-theory shows that the annual cycles in microphysical and optical aerosol properties have a common cause. By comparison with observations at other Antarctic stations, it is shown that the annual cycle is not a local phenomenon, but common to Central Antarctic baseline air masses. Observations of ground-level ozone at Troll as well as backward plume calculations for the air masses arriving at Troll demonstrate that the baseline air masses originate from the free troposphere and lower stratosphere region, and descend over the Central Antarctic continent. The Antarctic summer PNSD is dominated by particles with diameters < 100 nm recently formed from the gas-phase despite the absence of external sources of condensible gases. The total particle volume in Antarctic baseline aerosol is linearly correlated with the integral insolation the aerosol received on its transport pathway, and the photooxidative production of particle volume is mostly limited by photooxidative capacity, not availability of aerosol precursor gases. The photooxidative particle volume formation rate in Central Antarctic baseline air is quantified to 207 ± 4 μm3/(MJ m). Further research is proposed to investigate the applicability of this number to other atmospheric reservoirs, and to use the observed annual cycle in Antarctic baseline aerosol properties as a benchmark for the representation of natural atmospheric aerosol processes in climate models.

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