scholarly journals A pseudo-Lagrangian model study of the size distribution properties over Scandinavia: transport from Aspvreten to Värriö

2004 ◽  
Vol 4 (6) ◽  
pp. 7757-7794 ◽  
Author(s):  
P. Tunved ◽  
H. Korhonen ◽  
J. Ström ◽  
H.-C. Hansson ◽  
K. E. J. Lehtinen ◽  
...  
Keyword(s):  
Organic Compound ◽  
Size Distribution ◽  
Dry Deposition ◽  
Absolute Magnitude ◽  
Lagrangian Model ◽  
Aerosol Size Distribution ◽  
Base Case ◽  
Aerosol Model ◽  
Aerosol Mass ◽  
Model Study

Abstract. The evolution of the aerosol size distribution during transport between Aspvreten (58.8° N, 17.4° E) and Värriö (67.46° N, 29.35° E) was studied using a pseudo-Lagrangian approach. Aerosol dynamic processes were studied and interpreted utilizing a state-of-the-art aerosol dynamic box model UHMA (University of Helsinki Multicomponent Aerosol model) complemented with OH, NO3, O3 and terpene chemistry. In the model simulations, the growth and formation of aerosol particles was controlled by sulphuric acid, ammonia, water and an unidentified low volatile organic compound. This organic compound was assumed to be a product of terpene oxidation with a yield of 13% in the base case conditions. Changes of aerosol size distribution properties during transport between the stations were examined in twelve clear sky cases. On average, the modelled number agreed fairly well with observations. Mass concentration was overestimated by 10%. Apart from dilution, the only removal mechanism for aerosol mass is dry deposition. A series of sensitivity tests performed revealed that the absolute magnitude of dry deposition effects on the aerosol size distribution is slow overall. Furthermore, nucleation does not leave a significant contribution to aerosol number in the selected cases. The sensitivity of the modelled size distribution to concentration of precursor gases and oxidants is, however, obvious. In order to explain observed mass increase during transport we conclude that a yield of low volatile products from oxidation of terpenes of 10–15% is required to explain observed growth rates. Coagulation is acknowledged to be highly important in modelled cases.

scholarly journals Cloud Activating Properties of Aerosol Observed during CELTIC

2007 ◽  
Vol 64 (2) ◽  
pp. 441-459 ◽  
Author(s):  
Craig A. Stroud ◽  
Athanasios Nenes ◽  
Jose L. Jimenez ◽  
Peter F. DeCarlo ◽  
J. Alex Huffman ◽  
...  
Keyword(s):  
Kinetic Model ◽  
Size Distribution ◽  
Organic Aerosol ◽  
Aerosol Size Distribution ◽  
Model Bias ◽  
Aerosol Composition ◽  
Ambient Aerosol ◽  
Aerosol Mass ◽  
Mass Fractions ◽  
Mass Size

Abstract Measurements of aerosol size distribution, chemical composition, and cloud condensation nuclei (CCN) concentration were performed during the Chemical Emission, Loss, Transformation, and Interactions with Canopies (CELTIC) field program at Duke Forest in North Carolina. A kinetic model of the cloud activation of ambient aerosol in the chamber of the CCN instrument was used to perform an aerosol–CCN closure study. This study advances prior investigations by employing a novel fitting algorithm that was used to integrate scanning mobility particle sizer (SMPS) measurements of aerosol number size distribution and aerosol mass spectrometer (AMS) measurements of the mass size distribution for sulfate, nitrate, ammonium, and organics into a single, coherent description of the ambient aerosol in the size range critical to aerosol activation (around 100-nm diameter). Three lognormal aerosol size modes, each with a unique internally mixed composition, were used as input into the kinetic model. For the two smaller size modes, which control CCN number concentration, organic aerosol mass fractions for the defined cases were between 58% and 77%. This study is also unique in that the water vapor accommodation coefficient was estimated based on comparing the initial timing for CCN activation in the instrument chamber with the activation predicted by the kinetic model. The kinetic model overestimated measured CCN concentrations, especially under polluted conditions. Prior studies have attributed a positive model bias to an incomplete understanding of the aerosol composition, especially the role of organics in the activation process. This study shows that including measured organic mass fractions with an assumed organic aerosol speciation profile (pinic acid, fulvic acid, and levoglucosan) and an assumed organic aerosol solubility of 0.02 kg kg−1 still resulted in a significant model positive bias for polluted case study periods. The slope and y intercept for the CCN predicted versus CCN observed regression was found to be 1.9 and −180 cm−3, respectively. The overprediction generally does not exceed uncertainty limits but is indicative that a bias exists in the measurements or application of model. From this study, uncertainties in the particle number and mass size distributions as the cause for the model bias can be ruled out. The authors are also confident that the model is including the effects of growth kinetics on predicted activated number. However, one cannot rule out uncertainties associated with poorly characterized CCN measurement biases, uncertainties in assumed organic solubility, and uncertainties in aerosol mixing state. Sensitivity simulations suggest that assuming either an insoluble organic fraction or external aerosol mixing were both sufficient to reconcile the model bias.

scholarly journals Technical Note: A new SIze REsolved Aerosol Model (SIREAM)

2007 ◽  
Vol 7 (6) ◽  
pp. 1537-1547 ◽  
Author(s):  
E. Debry ◽  
K. Fahey ◽  
K. Sartelet ◽  
B. Sportisse ◽  
M. Tombette
Keyword(s):  
Size Distribution ◽  
Transport Model ◽  
Three Dimensional ◽  
Technical Note ◽  
Aerosol Size Distribution ◽  
Short Paper ◽  
Chemistry Transport Model ◽  
Dynamical Mass ◽  
Aerosol Model ◽  
Transfer Method

Abstract. We briefly present in this short paper a new SIze REsolved Aerosol Model (SIREAM) which simulates the evolution of atmospheric aerosol by solving the General Dynamic Equation (GDE). SIREAM segregates the aerosol size distribution into sections and solves the GDE by splitting coagulation and condensation/evaporation-nucleation. A quasi-stationary sectional approach is used to describe the size distribution change due to condensation/evaporation, and a hybrid equilibrium/dynamical mass-transfer method has been developed to lower the computational burden. SIREAM uses the same physical parameterizations as those used in the Modal Aerosol Model, MAM Sartelet et al. (2006). It is hosted in the modeling system Polyphemus Mallet et al., 2007, but can be linked to any other three-dimensional Chemistry-Transport Model.

scholarly journals Technical Note: A new SIze REsolved Aerosol Model (SIREAM)

2006 ◽  
Vol 6 (6) ◽  
pp. 11845-11875 ◽  
Author(s):  
E. Debry ◽  
K. Fahey ◽  
K. Sartelet ◽  
B. Sportisse ◽  
M. Tombette
Keyword(s):  
Size Distribution ◽  
Atmospheric Aerosol ◽  
Transport Model ◽  
Three Dimensional ◽  
Technical Note ◽  
Aerosol Size Distribution ◽  
Short Paper ◽  
Chemistry Transport Model ◽  
Aerosol Model ◽  
General Dynamic

Abstract. We briefly present in this short paper a new SIze REsolved Aerosol Model (SIREAM) which simulates the evolution of atmospheric aerosol by solving the General Dynamic Equation (GDE). SIREAM segregates the aerosol size distribution into sections and solves the GDE by splitting coagulation and condensation/evaporation. A moving sectional approach is used to describe the size distribution change due to condensation/evaporation and a hybrid method has been developed to lower the computational burden. SIREAM uses the same physical parameterizations as those used in the Modal Aerosol Model, MAM sartelet05development. It is hosted in the modeling system POLYPHEMUS (Mallet et al., 2006) but can be linked to any other three-dimensional Chemistry-Transport Model.

scholarly journals Vertical distribution of aerosols in the vicinity of Mexico City during MILAGRO-2006 Campaign

2010 ◽  
Vol 10 (3) ◽  
pp. 1017-1030 ◽  
Author(s):  
P. A. Lewandowski ◽  
W. E. Eichinger ◽  
H. Holder ◽  
J. Prueger ◽  
J. Wang ◽  
...  
Keyword(s):  
Size Distribution ◽  
Mexico City ◽  
Mass Concentration ◽  
Heavy Traffic ◽  
Aerosol Size Distribution ◽  
Lidar System ◽  
Aerosol Mass ◽  
Aerosol Mass Concentration ◽  
Lidar Measurements ◽  
Ground Based Lidar

Abstract. On 7 March 2006, a mobile, ground-based, vertical pointing, elastic lidar system made a North-South transect through the Mexico City basin. Column averaged, aerosol size distribution (ASD) measurements were made on the ground concurrently with the lidar measurements. The ASD ground measurements allowed calculation of the column averaged mass extinction efficiency (MEE) for the lidar system (1064 nm). The value of column averaged MEE was combined with spatially resolved lidar extinction coefficients to produce total aerosol mass concentration estimates with the resolution of the lidar (1.5 m vertical spatial and 1 s temporal). Airborne ASD measurements from DOE G-1 aircraft made later in the day on 7 March 2006, allowed the evaluation of the assumptions of constant ASD with height and time used for estimating the column averaged MEE. The results showed that the aerosol loading within the basin is about twice what is observed outside of the basin. The total aerosol base concentrations observed in the basin are of the order of 200 μg/m3 and the base levels outside are of the order of 100 μg/m3. The local heavy traffic events can introduce aerosol levels near the ground as high as 900 μg/m3. The article presents the methodology for estimating aerosol mass concentration from mobile, ground-based lidar measurements in combination with aerosol size distribution measurements. An uncertainty analysis of the methodology is also presented.

scholarly journals An investigation of processes controlling the evolution of the boundary layer aerosol size distribution properties at the Swedish background station Aspvreten

2004 ◽  
Vol 4 (11/12) ◽  
pp. 2581-2592 ◽  
Author(s):  
P. Tunved ◽  
J. Ström ◽  
H.-C. Hansson
Keyword(s):  
Size Distribution ◽  
Wet Deposition ◽  
Source Area ◽  
Aerosol Size Distribution ◽  
Back Trajectory ◽  
Main Process ◽  
Size Distributions ◽  
Back Trajectory Analysis ◽  
Aerosol Mass ◽  
The One

Abstract. Aerosol size distributions have been measured at the Swedish background station Aspvreten (58.8° N, 17.4° E). Different states of the aerosol were determined using a novel application of cluster analysis. The analysis resulted in eight different clusters capturing different stages of the aerosol lifecycle. The atmospheric aerosol size distributions were interpreted as belonging to fresh, intermediate and aged types of size distribution. With aid of back trajectory analysis we present statistics concerning the relation of source area and different meteorological parameters using a non-Lagrangian approach. Source area is argued to be important although not sufficient to describe the observed aerosol properties. Especially processing by clouds and precipitation is shown to be crucial for the evolution of the aerosol size distribution. As much as 60% of the observed size distributions present features that are likely to be related to cloud processes or wet deposition. The lifetime properties of different sized aerosols are discussed by means of measured variability of the aerosol size distribution. Processing by clouds and precipitation is shown to be especially crucial in the size range 100 nm and larger. This indicates an approximate limit for activation in clouds to 100 nm in this type of environment. The aerosol lifecycle is discussed. Size distributions indicating signs of recent new particle formation (~30% of the observed size distributions) represent the first stage in the lifecycle. Aging of the aerosol size distribution may follow two branches: either growth by condensation and coagulation or processing by non-precipitating clouds. In both cases mass is accumulated. Wet removal is the main process capable of removing aerosol mass. Wet deposition is argued to be an important mechanism in reaching a state where nucleation may occur (i.e. sufficiently low aerosol surface area) in environments similar to the one studied.

scholarly journals Improvement of stratospheric aerosol extinction retrieval from OMPS/LP using a new aerosol model

2018 ◽  
Vol 11 (12) ◽  
pp. 6495-6509 ◽  
Author(s):  
Zhong Chen ◽  
Pawan K. Bhartia ◽  
Robert Loughman ◽  
Peter Colarco ◽  
Matthew DeLand
Keyword(s):  
Size Distribution ◽  
Gamma Function ◽  
Spectral Dependence ◽  
Stratospheric Aerosol ◽  
Cumulative Distribution ◽  
Aerosol Size Distribution ◽  
Retrieval Algorithm ◽  
Aerosol Extinction ◽  
Aerosol Model ◽  
The Impact

Abstract. The Ozone Mapping and Profiler Suite Limb Profiler (OMPS/LP) has been flying on the Suomi National Polar-orbiting Partnership (S-NPP) satellite since October 2011. It is designed to produce ozone and aerosol vertical profiles at ∼2 km vertical resolution over the entire sunlit globe. Aerosol extinction profiles are computed with Mie theory using radiances measured at 675 nm. The operational Version 1.0 (V1.0) aerosol extinction retrieval algorithm assumes a bimodal lognormal aerosol size distribution (ASD) whose parameters were derived by combining an in situ measurement of aerosol microphysics with the Stratospheric Aerosol and Gas Experiment (SAGE II) aerosol extinction climatology. Internal analysis indicates that this bimodal lognormal ASD does not sufficiently explain the spectral dependence of LP-measured radiances. In this paper we describe the derivation of an improved aerosol size distribution, designated Version 1.5 (V1.5), for the LP retrieval algorithm. The new ASD uses a gamma function distribution that is derived from Community Aerosol and Radiation Model for Atmospheres (CARMA)-calculated results. A cumulative distribution fit derived from the gamma function ASD gives better agreement with CARMA results at small particle radii than bimodal or unimodal functions. The new ASD also explains the spectral dependence of LP-measured radiances better than the V1.0 ASD. We find that the impact of our choice of ASD on the retrieved extinctions varies strongly with the underlying reflectivity of the scene. Initial comparisons with collocated extinction profiles retrieved at 676 nm from the SAGE III instrument on the International Space Station (ISS) show a significant improvement in agreement for the LP V1.5 retrievals. Zonal mean extinction profiles agree to within 10  % between 19 and 29 km, and regression fits of collocated samples show improved correlation and reduced scatter compared to the V1.0 product. This improved agreement will motivate development of more sophisticated ASDs from CARMA results that incorporate latitude, altitude and seasonal variations in aerosol properties.

scholarly journals New trajectory driven aerosol and chemical process model: chemical and aerosol Lagrangian model (CALM)

2010 ◽  
Vol 10 (6) ◽  
pp. 15197-15261
Author(s):  
P. Tunved ◽  
D. G. Partridge ◽  
H. Korhonen
Keyword(s):  
Size Distribution ◽  
Process Model ◽  
Winter Season ◽  
Lagrangian Model ◽  
Cloud Formation ◽  
Aerosol Size Distribution ◽  
Cloud Processing ◽  
Primary Reactions ◽  
Average Size ◽  
Good Agreement

Abstract. A new Chemical and Aerosol Lagrangian Model (CALM) have been developed and tested. The model incorporates all central aerosol dynamical processes, from nucleation, condensation, coagulation and deposition to cloud formation and in-cloud processing. The model is tested and evaluated against observations performed at the SMEAR II station located at Hyytiälä (61°51' N, 24°17' E) over a time period of two years, 2000–2001. The model shows good agreement with measurements throughout most of the year, but fails in reproducing the aerosol properties during the winter season, resulting in poor agreement between model and measurements especially during December–January. Nevertheless, through the rest of the year both trends and magnitude of modal concentrations show good agreement with observation, as do the monthly average size distribution properties. The model is also shown to capture individual nucleation events to a certain degree. This indicates that nucleation largely is controlled by the availability of nucleating material (as prescribed by the [H2SO4]), availability of condensing material (in this model 15% of primary reactions of monoterpenes (MT) are assumed to produce low volatile species) and the properties of the size distribution (more specifically, the condensation sink). This is further demonstrated by the fact that the model captures the annual trend in nuclei mode concentration. The model is also used, alongside sensitivity tests, to examine which processes dominate the aerosol size distribution physical properties. It is shown, in agreement with previous studies, that nucleation governs the number concentration while transport from clean areas takes place. It is also shown that primary number emissions almost exclusively govern the CN concentration when air from Central Europe is advected north over Scandinavia. We also show that biogenic emissions have a large influence on the amount of potential CCN observed over the boreal region, as shown by the agreement between observations and modeled results for the receptor SMEAR II, Hyytiälä, during the studied period.

scholarly journals New trajectory-driven aerosol and chemical process model Chemical and Aerosol Lagrangian Model (CALM)

2010 ◽  
Vol 10 (21) ◽  
pp. 10161-10185 ◽  
Author(s):  
P. Tunved ◽  
D. G. Partridge ◽  
H. Korhonen
Keyword(s):  
Size Distribution ◽  
Process Model ◽  
Winter Season ◽  
Lagrangian Model ◽  
Cloud Formation ◽  
Aerosol Size Distribution ◽  
Cloud Processing ◽  
Primary Reactions ◽  
Average Size ◽  
Good Agreement

Abstract. A new Chemical and Aerosol Lagrangian Model (CALM) has been developed and tested. The model incorporates all central aerosol dynamical processes, from nucleation, condensation, coagulation and deposition to cloud formation and in-cloud processing. The model is tested and evaluated against observations performed at the SMEAR II station located at Hyytiälä (61° 51' N, 24° 17' E) over a time period of two years, 2000–2001. The model shows good agreement with measurements throughout most of the year, but fails in reproducing the aerosol properties during the winter season, resulting in poor agreement between model and measurements especially during December–January. Nevertheless, through the rest of the year both trends and magnitude of modal concentrations show good agreement with observation, as do the monthly average size distribution properties. The model is also shown to capture individual nucleation events to a certain degree. This indicates that nucleation largely is controlled by the availability of nucleating material (as prescribed by the [H2SO4]), availability of condensing material (in this model 15% of primary reactions of monoterpenes (MT) are assumed to produce low volatile species) and the properties of the size distribution (more specifically, the condensation sink). This is further demonstrated by the fact that the model captures the annual trend in nuclei mode concentration. The model is also used, alongside sensitivity tests, to examine which processes dominate the aerosol size distribution physical properties. It is shown, in agreement with previous studies, that nucleation governs the number concentration during transport from clean areas. It is also shown that primary number emissions almost exclusively govern the CN concentration when air from Central Europe is advected north over Scandinavia. We also show that biogenic emissions have a large influence on the amount of potential CCN observed over the boreal region, as shown by the agreement between observations and modeled results for the receptor SMEAR II, Hyytiälä, during the studied period.

scholarly journals Improvement of stratospheric aerosol extinction retrieval from OMPS/LP using a new aerosol model

2018 ◽  
Author(s):  
Zhong Chen ◽  
Pawan K. Bhartia ◽  
Robert Loughman ◽  
Peter Colarco ◽  
Matthew DeLand
Keyword(s):  
Size Distribution ◽  
Gamma Function ◽  
Spectral Dependence ◽  
Stratospheric Aerosol ◽  
Cumulative Distribution ◽  
Aerosol Size Distribution ◽  
Retrieval Algorithm ◽  
Aerosol Extinction ◽  
Aerosol Model ◽  
The Impact

Abstract. The Ozone Mapping and Profiler Suite Limb Profiler (OMPS/LP) has been flying on the Suomi NPP satellite since October 2011. It is designed to produce ozone and aerosol vertical profiles at ~2 km vertical resolution over the entire sunlit globe. Aerosol extinction profiles are computed with Mie theory using radiances measured at 675 nm. The operational Version 1.0 (V1.0) aerosol extinction retrieval algorithm assumes a bimodal lognormal aerosol size distribution (ASD) whose parameters were derived by combining an in situ measurement of aerosol microphysics with the SAGE II aerosol extinction climatology. Internal analysis indicates that this bimodal lognormal ASD does not sufficiently explain the spectral dependence of LP measured radiances. In this paper we describe the derivation of an improved aerosol size distribution, designated Version 1.5 (V1.5), for the LP retrieval algorithm. The new ASD uses a gamma function distribution that is derived from Community Aerosol and Radiation Model for Atmospheres (CARMA) calculated results. A cumulative distribution fit derived from the gamma function ASD gives better agreement with CARMA results at small particle radii than bimodal or unimodal functions. The new ASD also explains the spectral dependence of LP measured radiances better than the V1.0 ASD. We find that the impact of our choice of ASD on the retrieved extinctions varies strongly with the underlying reflectivity of the scene. Initial comparisons with co-located extinction profiles retrieved at 676 nm from the SAGE III/ISS instrument show a significant improvement in agreement for the LP V1.5 retrievals. Zonal mean extinction profiles agree to within 10 % between 19–29 km, and regression fits of collocated samples show improved correlation and reduced scatter compared to the V1.0 product. This improved agreement will motivate development of more sophisticated ASDs from CARMA results that incorporate latitude, altitude, and seasonal variations in aerosol properties.

scholarly journals Physical properties of secondary photochemical aerosol from OH oxidation of a cyclic siloxane

2019 ◽  
Vol 19 (3) ◽  
pp. 1649-1664 ◽  
Author(s):  
Nathan J. Janechek ◽  
Rachel F. Marek ◽  
Nathan Bryngelson ◽  
Ashish Singh ◽  
Robert L. Bullard ◽  
...  
Keyword(s):  
Size Distribution ◽  
Flow Reactor ◽  
Oxidation Products ◽  
Aerosol Size Distribution ◽  
Atmospheric Models ◽  
Aerosol Mass ◽  
Differential Mobility Analysis ◽  
Mass Fractions ◽  
High Production ◽  
Seed Aerosol

Abstract. Cyclic volatile methyl siloxanes (cVMS) are high-production chemicals present in many personal care products. They are volatile, hydrophobic, and relatively long-lived due to slow oxidation kinetics. Evidence from chamber and ambient studies indicates that oxidation products may be found in the condensed aerosol phase. In this work, we use an oxidation flow reactor to produce ∼100 µg m−3 of organosilicon aerosol from OH oxidation of decamethylcyclopentasiloxane (D5) with aerosol mass fractions (i.e., yields) of 0.2–0.5. The aerosols were assessed for concentration, size distribution, morphology, sensitivity to seed aerosol, hygroscopicity, volatility and chemical composition through a combination of aerosol size distribution measurement, tandem differential mobility analysis, and electron microscopy. Similar aerosols were produced when vapor from solid antiperspirant was used as the reaction precursor. Aerosol yield was sensitive to chamber OH and to seed aerosol, suggesting sensitivity of lower-volatility species and recovered yields to oxidation conditions and chamber operation. The D5 oxidation aerosol products were relatively non-hygroscopic, with an average hygroscopicity kappa of ∼0.01, and nearly non-volatile up to 190 ∘C temperature. Parameters for exploratory treatment as a semi-volatile organic aerosol in atmospheric models are provided.

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