scholarly journals Aerosol physical and optical properties and their relationship to aerosol composition in the free troposphere at Izaña, Tenerife, Canary Islands, during July 1995

2000 ◽  
Vol 105 (D11) ◽  
pp. 14677-14700 ◽  
Author(s):  
H. Maring ◽  
D. L. Savoie ◽  
M. A. Izaguirre ◽  
C. McCormick ◽  
R. Arimoto ◽  
...  
Keyword(s):  
Optical Properties ◽  
Canary Islands ◽  
Free Troposphere ◽  
Aerosol Composition

scholarly journals Aerosol chemical and optical properties over the Paris area within ESQUIF project

2006 ◽  
Vol 6 (11) ◽  
pp. 3257-3280 ◽  
Author(s):  
A. Hodzic ◽  
R. Vautard ◽  
P. Chazette ◽  
L. Menut ◽  
B. Bessagnet
Keyword(s):  
Optical Properties ◽  
Secondary Organic Aerosols ◽  
Organic Aerosols ◽  
Dust Particles ◽  
Aerosol Size Distribution ◽  
Aerosol Composition ◽  
Aerosol Mass ◽  
Coarse Mode ◽  
Paris Area ◽  
Flight Trajectories

Abstract. Aerosol chemical and optical properties are extensively investigated for the first time over the Paris Basin in July 2000 within the ESQUIF project. The measurement campaign offers an exceptional framework to evaluate the performances of the chemistry-transport model CHIMERE in simulating concentrations of gaseous and aerosol pollutants, as well as the aerosol-size distribution and composition in polluted urban environments against ground-based and airborne measurements. A detailed comparison of measured and simulated variables during the second half of July with particular focus on 19 and 31 pollution episodes reveals an overall good agreement for gas-species and aerosol components both at the ground level and along flight trajectories, and the absence of systematic biases in simulated meteorological variables such as wind speed, relative humidity and boundary layer height as computed by the MM5 model. A good consistency in ozone and NO concentrations demonstrates the ability of the model to reproduce the plume structure and location fairly well both on 19 and 31 July, despite an underestimation of the amplitude of ozone concentrations on 31 July. The spatial and vertical aerosol distributions are also examined by comparing simulated and observed lidar vertical profiles along flight trajectories on 31 July and confirm the model capacity to simulate the plume characteristics. The comparison of observed and modeled aerosol components in the southwest suburb of Paris during the second half of July indicates that the aerosol composition is rather correctly reproduced, although the total aerosol mass is underestimated by about 20%. The simulated Parisian aerosol is dominated by primary particulate matter that accounts for anthropogenic and biogenic primary particles (40%), and inorganic aerosol fraction (40%) including nitrate (8%), sulfate (22%) and ammonium (10%). The secondary organic aerosols (SOA) represent 12% of the total aerosol mass, while the mineral dust accounts for 8%. The comparison demonstrates the absence of systematic errors in the simulated sulfate, ammonium and nitrates total concentrations. However, for nitrates the observed partition between fine and coarse mode is not reproduced. In CHIMERE there is a clear lack of coarse-mode nitrates. This calls for additional parameterizations in order to account for the heterogeneous formation of nitrate onto dust particles. Larger discrepancies are obtained for the secondary organic aerosols due to both inconsistencies in the SOA formation processes in the model leading to an underestimation of their mass and large uncertainties in the determination of the measured aerosol organic fraction. The observed mass distribution of aerosols is not well reproduced, although no clear explanation can be given.

Aerosol composition and related optical properties in the marine boundary layer over the Baltic Sea

2001 ◽  
Vol 32 (8) ◽  
pp. 933-955 ◽  
Author(s):  
J Kuśmierczyk-Michulec ◽  
M Schulz ◽  
S Ruellan ◽  
O Krüger ◽  
E Plate ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Optical Properties ◽  
Baltic Sea ◽  
Marine Boundary Layer ◽  
The Baltic Sea ◽  
Aerosol Composition ◽  
The Baltic

scholarly journals The importance of Asia as a source of black carbon to the European Arctic during springtime 2013

2015 ◽  
Vol 15 (20) ◽  
pp. 11537-11555 ◽  
Author(s):  
D. Liu ◽  
B. Quennehen ◽  
E. Darbyshire ◽  
J. D. Allan ◽  
P. I. Williams ◽  
...  
Keyword(s):  
Black Carbon ◽  
Arctic Sea Ice ◽  
Anthropogenic Sources ◽  
The Arctic ◽  
Geometric Standard Deviation ◽  
Free Troposphere ◽  
Aerosol Composition ◽  
Upper Troposphere ◽  
European Arctic ◽  
Mean Concentration

Abstract. Black carbon aerosol (BC) deposited to the Arctic sea ice or present in the free troposphere can significantly affect the Earth's radiation budget at high latitudes yet the BC burden in these regions and the regional source contributions are poorly constrained. Aircraft measurements of aerosol composition in the European Arctic were conducted during the Aerosol–Cloud Coupling And Climate Interactions in the Arctic (ACCACIA) campaign in March 2013. Pollutant plumes were encountered throughout the lower to upper Arctic troposphere featuring enhancements in CO and aerosol mass loadings, which were chemically speciated into BC and non-refractory sulphate and organic matter. FLEXPART-WRF simulations have been performed to evaluate the likely contribution to the pollutants from regional ground sources. By combining up-to-date anthropogenic and open fire biomass burning (OBB) inventories, we have been able to compare the contributions made to the observed pollution layers from the sources of eastern/northern Asia (AS), Europe (EU) and North America (NA). Over 90 % of the contribution to the BC was shown to arise from non-OBB anthropogenic sources. AS sources were found to be the major contributor to the BC burden, increasing background BC loadings by a factor of 3–5 to 100.8 ± 48.4 ng sm−3 (in standard air m3 at 273.15 K and 1013.25 mbar) and 55.8 ± 22.4 ng sm−3 in the middle and upper troposphere respectively. AS plumes close to the tropopause (about 7.5–8 km) were also observed, with BC concentrations ranging from 55 to 73 ng sm−3, which will potentially have a significant radiative impact. EU sources influenced the middle troposphere with a BC mean concentration of 70.8 ± 39.1 ng sm−3 but made a minor contribution to the upper troposphere due to the relatively high latitude of the source region. The contribution of NA was shown to be much lower at all altitudes with BC mean concentration of 20 ng sm−3. The BC transported to the Arctic is mixed with a non-BC volume fraction representing between 90–95 % of the mass, and has a relatively uniform core size distribution with mass median diameter 190–210 nm and geometric standard deviation σg = 1.55–1.65 and this varied little across all source regions. It is estimated that 60–95 % of BC is scavenged between emission and receptor based on BC / ΔCO comparisons between source inventories and measurement. We show that during the springtime of 2013, the anthropogenic pollution particularly from sources in Asia, contributed significantly to BC across the European Arctic free troposphere. In contrast to previous studies, the contribution from open wildfires was minimal. Given that Asian pollution is likely to continue to rise over the coming years, it is likely that the radiative forcing in the Arctic will also continue to increase.

scholarly journals Aerosol chemical and optical properties over the Paris area within ESQUIF project

2006 ◽  
Vol 6 (1) ◽  
pp. 401-454 ◽  
Author(s):  
A. Hodzic ◽  
R. Vautard ◽  
P. Chazette ◽  
L. Menut ◽  
B. Bessagnet
Keyword(s):  
Optical Properties ◽  
Secondary Organic Aerosols ◽  
Organic Aerosols ◽  
Dust Particles ◽  
Aerosol Size Distribution ◽  
Aerosol Composition ◽  
Aerosol Mass ◽  
Coarse Mode ◽  
Paris Area ◽  
Flight Trajectories

Abstract. Aerosol chemical and optical properties are extensively investigated for the first time over the Paris Basin in July 2000 within the ESQUIF project. The measurement campaign offers an exceptional framework to evaluate the performances of the chemistry-transport model CHIMERE in simulating concentrations of gaseous and aerosol pollutants, as well as the aerosol-size distribution and composition in polluted urban environment against ground-based and airborne measurements. A detailed comparison of measured and simulated variables during the second half of July with particular focus on 19 and 31 pollution episodes reveals an overall good agreement for gas-species and aerosol components both at the ground level and along flight trajectories, and the absence of systematic biases in simulated meteorological variables such as wind speed, relative humidity and boundary layer height as computed by the MM5 model. A good consistency in ozone and NO concentrations demonstrates the ability of the model to reproduce fairly well the plume structure and location both on 19 and 31 July, despite an underestimation of the amplitude of ozone concentrations on 31 July. The spatial and vertical aerosol distributions are also examined by comparing simulated and observed lidar vertical profiles along flight trajectories on 31 July and confirmed the model capacity to simulate the plume characteristics. The comparison of observed and modeled aerosol components in the southwest suburb of Paris during the second half of July indicated that the aerosol composition is rather correctly reproduced, although the total aerosol mass is underestimated of about 20%. The simulated Parisian aerosol is dominated by primary particulate matter that accounts for anthropogenic and biogenic primary particles (40%) and inorganic aerosol fraction (40%) including nitrate (8%), sulfate (22%) and ammonium (10%). The secondary organic aerosols (SOA) represent 12% of the total aerosol mass, while the mineral dust accounts for 8%. The comparison demonstrated the absence of systematic errors in the simulated sulfate, ammonium and nitrates total concentrations. However for nitrates the observed partition between fine and coarse mode is not reproduced. In CHIMERE there is a clear lack of coarse-mode nitrates. This calls for additional parameterizations in order to account for the heterogeneous formation of nitrate onto dust particles. Larger discrepancies are obtained for the secondary organic aerosols due to both inconsistencies in the SOA formation processes in the model leading to an underestimation of their mass and large uncertainties in the determination of the measured aerosol organic fraction. The observed mass distribution of aerosols is not well reproduced, although no clear explanation can be given.

scholarly journals Optical properties of atmospheric fine particles near Beijing during the HOPE-J<sup>3</sup>A Campaign

2015 ◽  
Vol 15 (22) ◽  
pp. 33675-33730
Author(s):  
X. Xu ◽  
W. Zhao ◽  
Q. Zhang ◽  
S. Wang ◽  
B. Fang ◽  
...  
Keyword(s):  
Refractive Index ◽  
Optical Properties ◽  
Fine Particles ◽  
Complex Refractive Index ◽  
Single Scattering ◽  
Single Scattering Albedo ◽  
Organic Mass ◽  
Absorption Coefficients ◽  
Aerosol Composition ◽  
Inorganic Species

Abstract. The optical properties and chemical composition of PM1.0 (particulate with an aerodynamic diameter of less than 1.0 μm) particles in a suburban environment (Huairou) near the mega-city Beijing were measured during the HOPE-J3A (Haze Observation Project Especially for Jing-Jin-Ji Area) field campaign. The campaign covered the period November 2014 to January 2015 during the winter coal heating season. The average and standard deviations for the extinction, scattering, absorption coefficients, and the aerosol single scattering albedo (SSA) at λ = 470 nm during the measurement period were 201 ± 240, 164 ± 202, 37 ± 43 Mm-1, and 0.80 ± 0.08, respectively. The mean mass scattering (MSE) and absorption (MAE) efficiencies were 4.77 ± 0.01 and 0.87 ± 0.03 m2g-1, respectively. Highly time-resolved air pollution episodes clearly show the dramatic evolution of the PM1.0 size distribution, extensive optical properties (extinction, scattering, and absorption coefficients) and intensive optical properties (single scattering albedo and complex refractive index) during haze formation, development and decline. Time periods were classified into three different pollution levels (clear, slightly polluted, and polluted) for further analysis. It was found that: (1) The diurnal patterns of the aerosol extinction, scattering, absorption coefficients, and SSA differed for the three pollution classes. (2) The real and imaginary part of complex refractive index (CRI) increased, while the SSA decreased from clear to polluted days. (3) The relative contributions of organic and inorganic species to observed aerosol composition changed significantly from clear to polluted days: the organic mass fraction decreased (50 to 43 %) while the proportion of sulfates, nitrates, and ammonium increased strongly (34 to 44 %). (4) The fractional contribution of chemical components to extinction coefficients was calculated by using the modified IMPROVE algorithm. Organic mass was the largest contributor (58 %) to the total extinction of PM1.0. When the air quality deteriorated, the change of the relative contribution of sulfate aerosol to the total extinction was small, but the contribution of nitrate aerosol increased significantly (from 17 % on clear days to 23 % on polluted days). (5) The observed mass scattering efficiencies increased consistently with the pollution extent, however, the observed mass absorption efficiencies increased consistently with increasing mass concentration in slightly pollution conditions, but decreased under polluted conditions.

scholarly journals Benefit of depolarization ratio at λ = 1064 nm for the retrieval of the aerosol microphysics from lidar measurements

2014 ◽  
Vol 7 (5) ◽  
pp. 5095-5115
Author(s):  
J. Gasteiger ◽  
V. Freudenthaler
Keyword(s):  
Optical Properties ◽  
Mass Concentration ◽  
Single Scattering ◽  
Sufficient Information ◽  
Depolarization Ratio ◽  
Aerosol Composition ◽  
Microphysical Properties ◽  
Lidar Measurements ◽  
Increased Sensitivity ◽  
Linear Depolarization Ratio

Abstract. A better quantification of aerosol microphysical and optical properties is required to improve the modelling of aerosol effects on weather and climate. This task is methodologically demanding due to the huge diversity of aerosol composition and of their shape and size distribution, and due to the complexity of the relation between the microphysical and optical properties. Lidar remote sensing is a valuable tool to gain spatially and temporally resolved information on aerosol properties. Advanced lidar systems provide sufficient information on the aerosol optical properties for the retrieval of important aerosol microphysical properties. Recently, the mass concentration of transported volcanic ash, which is relevant for the flight safety of airplanes, was retrieved from measurements of such lidar systems in Southern Germany. The relative uncertainty of the retrieved mass concentration was on the order of ±50%. The present study investigates improvements of the retrieval accuracy when the capability of measuring the linear depolarization ratio at 1064 nm is added to the lidar setup. The lidar setups under investigation are based on the setup of MULIS and POLIS of the LMU in Munich which measure the linear depolarization ratio at 355 nm and 532 nm with high accuracy. By comparing results of retrievals applied to simulated lidar measurements with and without the depolarization at 1064 nm it is found that the availability of 1064 nm depolarization measurements reduces the uncertainty of the retrieved mass concentration and effective particle size by a factor of about 2–3. This significant improvement in accuracy is the result of the increased sensitivity of the lidar setup to larger particles. However, the retrieval of the single scattering albedo, which is relevant for the radiative transfer in aerosol layers, does hardly benefit from the availability of 1064 nm depolarization measurements.

scholarly journals Evidence of the complexity of aerosol transport in the lower troposphere on the Namibian coast during AEROCLO-sA

2019 ◽  
Vol 19 (23) ◽  
pp. 14979-15005
Author(s):  
Patrick Chazette ◽  
Cyrille Flamant ◽  
Julien Totems ◽  
Marco Gaetani ◽  
Gwendoline Smith ◽  
...  
Keyword(s):  
Sea Level ◽  
Southern Africa ◽  
Optical Thickness ◽  
Aerosol Optical Thickness ◽  
Back Trajectory ◽  
Aerosol Layer ◽  
Free Troposphere ◽  
Aerosol Composition ◽  
Mean Sea Level ◽  
Field Campaign

Abstract. The evolution of the vertical distribution and optical properties of aerosols in the free troposphere, above stratocumulus, is characterized for the first time over the Namibian coast, a region where uncertainties on aerosol–cloud coupling in climate simulations are significant. We show the high variability of atmospheric aerosol composition in the lower and middle troposphere during the Aerosols, Radiation and Clouds in southern Africa (AEROCLO-sA) field campaign (22 August–12 September 2017) around the Henties Bay supersite using a combination of ground-based, airborne and space-borne lidar measurements. Three distinct periods of 4 to 7 d are observed, associated with increasing aerosol loads (aerosol optical thickness at 550 nm ranging from ∼0.2 to ∼0.7), as well as increasing lofted aerosol layer depth and top altitude. Aerosols are observed up to 6 km above mean sea level during the later period. Aerosols transported within the free troposphere are mainly polluted dust (predominantly dust mixed with smoke from fires) for the first two periods (22 August–1 September 2017) and smoke for the last part (3–9 September) of the field campaign. As shown by Lagrangian back-trajectory analyses, the main contribution to the aerosol optical thickness over Henties Bay is shown to be due to biomass burning over Angola. Nevertheless, in early September, the highest aerosol layers (between 5 and 6 km above mean sea level) seem to come from South America (southern Brazil, Argentina and Uruguay) and reach Henties Bay after 3 to 6 d. Aerosols appear to be transported eastward by the midlatitude westerlies and towards southern Africa by the equatorward moving cut-off low originating from within the westerlies. All the observations show a very complex mixture of aerosols over the coastal regions of Namibia that must be taken into account when investigating aerosol radiative effects above stratocumulus clouds in the southeast Atlantic Ocean.

scholarly journals Evidence of the complexity of aerosol transport in the lower troposphere on the Namibian coast during AEROCLO-sA

2019 ◽  
Author(s):  
Patrick Chazette ◽  
Cyrille Flamant ◽  
Julien Totems ◽  
Marco Gaetani ◽  
Gwendoline Smith ◽  
...  
Keyword(s):  
South America ◽  
Sea Level ◽  
Complex Mixture ◽  
Lower Troposphere ◽  
Back Trajectory ◽  
Aerosol Layer ◽  
Free Troposphere ◽  
Aerosol Composition ◽  
Mean Sea Level ◽  
Field Campaign

Abstract. The evolution of the vertical distribution and optical properties of aerosols in the free troposphere, above stratocumulus, is analysed for the first time over the Namibian coast, a region where uncertainties on aerosol-cloud coupling in climate simulations are significant. We show the high variability of atmospheric aerosol composition in the lower and middle troposphere during the AEROCLO-sA field campaign (22 August–12 September 2017) around the Henties Bay supersite, using a combination of ground-based, airborne and space-borne lidar measurements. Three distinct periods of 4 to 7 days are observed, associated with increasing aerosol loads (aerosol optical thickness at 550 nm ranging from ~ 0.2 to ~ 0.7), as well as increasing aerosol layer depth and top altitude. Aerosols are observed up to 6 km above mean sea level during the later period. Aerosols transported within the free troposphere are mainly polluted dust (dust mixed with smoke from fires in Angola) for the first 2 periods (22 August–1 September 2017) and smoke (from Angola and South America) for the last part (3–9 September) of the field campaign. Lagrangian back trajectory analyses highlight that the highest aerosol layers (between 5 and 6 km above mean sea level) come from South America (Brazil, Argentina and Paraguay) and reach Henties Bay after 4 to 5 days. They are transported eastward by the mid latitude westerlies and towards Southern Africa by the equatorward moving cut-off low originating within the westerlies. This results in a very complex mixture of aerosols over the coastal regions of Namibia that must be taken into account when investigating aerosols radiative effects above stratocumulus clouds in the south east Atlantic Ocean.

scholarly journals The lofting of Western Pacific regional aerosol by island thermodynamics as observed around Borneo

2012 ◽  
Vol 12 (13) ◽  
pp. 5963-5983 ◽  
Author(s):  
N. H. Robinson ◽  
J. D. Allan ◽  
J. A. Trembath ◽  
P. D. Rosenberg ◽  
G. Allen ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Sea Breeze ◽  
Number Concentration ◽  
Western Pacific ◽  
Surface Mixed Layer ◽  
Free Troposphere ◽  
Mean Flow ◽  
Aerosol Composition ◽  
Air Mass ◽  
The Western Pacific

Abstract. Vertical profiles of aerosol chemical composition, number concentration and size were measured throughout the lower troposphere of Borneo, a large tropical island in the western Pacific Ocean. Aerosol composition, size and number concentration measurements (using an Aerodyne Aerosol Mass Spectrometer, Passive Cavity Aerosol Spectrometer Probe and Condensation Particle Counter, respectively) were made both upwind and downwind of Borneo, as well as over the island itself, on board the UK BAe-146 research aircraft as part of the OP3 project. Two meteorological regimes were identified – one dominated by isolated terrestrial convection (ITC) which peaked in the afternoon, and the other characterised by more regionally active mesoscale convective systems (MCS). Upwind profiles show aerosol to be confined to a shallow marine boundary layer below 930 ± 10 hPa (~760 m above sea level, a.s.l.). As this air mass advects over the island with the mean free troposphere synoptic flow during the ITC-dominated regime, it is convectively lofted above the terrestrial surface mixed layer to heights of between 945 ± 22 (~630 m a.s.l.) and 740 ± 44 hPa (~2740 m a.s.l.), consistent with a coupling between the synoptic steering level flow and island sea breeze circulations. Terrestrial aerosol was observed to be lofted into this higher layer through both moist convective uplift and transport through turbulent diurnal sea-breeze cells. At the peak of convective activity in the mid-afternoons, organic aerosol loadings in the lofted layer were observed to be substantially higher than in the morning (by a mean factor of three). This organic matter is dominated by secondary aerosol from processing of biogenic gas phase precursors. Aerosol number concentration profiles suggest formation of new particles aloft in the atmosphere. By the time the air mass reaches the west coast of the island, terrestrial aerosol is enhanced in the lofted layer. Such uplift of aerosol in Borneo is expected to increase aerosol lifetimes in the lower free troposphere downwind, as they are above the boundary layer and therefore less likely to be lost by wet or dry deposition. It is also likely to change the role they play in the semi-direct and direct aerosol effects. The long chain of islands extending from Malaysia to Australia may all similarly be expected to present an orographic barrier to low level mean flow. This would lead to significant transport of aerosol into the tropical free troposphere across the Western Pacific region.

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