Air Mass Characterisation During EOPACE: Aerosol Composition and Concentration

2000 ◽  
Author(s):  
Michael H. Smith
Keyword(s):  
Aerosol Composition ◽  
Air Mass

Aerosol Composition in Relation to Air Mass Movements in North China

1981 ◽  
pp. 287-301 ◽  
Author(s):  
JOHN W. WINCHESTER ◽  
MICHAEL DARZI ◽  
ALISTAIR C. D. LESLIE ◽  
WANG MINGXING ◽  
REN LIXIN ◽  
...  
Keyword(s):  
North China ◽  
Mass Movements ◽  
Aerosol Composition ◽  
Air Mass

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.

scholarly journals Air mass physiochemical characteristics over New Delhi: impacts on aerosol hygroscopicity and cloud condensation nuclei (CCN) formation

2020 ◽  
Vol 20 (11) ◽  
pp. 6953-6971 ◽  
Author(s):  
Zainab Arub ◽  
Sahil Bhandari ◽  
Shahzad Gani ◽  
Joshua S. Apte ◽  
Lea Hildebrandt Ruiz ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Size Distribution ◽  
Cloud Condensation Nuclei ◽  
Chemical Properties ◽  
Industrial Emissions ◽  
Condensation Nuclei ◽  
Aerosol Composition ◽  
Time Resolved ◽  
Air Mass ◽  
Air Masses

Abstract. Delhi is a megacity subject to high local anthropogenic emissions and long-range transport of pollutants. This work presents for the first time time-resolved estimates of hygroscopicity parameter (κ) and cloud condensation nuclei (CCN), spanning for more than a year, derived from chemical composition and size distribution data. As a part of the Delhi Aerosol Supersite (DAS) campaign, the characterization of aerosol composition and size distribution was conducted from January 2017 to March 2018. Air masses originating from the Arabian Sea (AS), Bay of Bengal (BB), and southern Asia (SA) exhibited distinct characteristics of time-resolved sub-micron non-refractory PM1 (NRPM1) species, size distributions, and CCN number concentrations. The SA air mass had the highest NRPM1 loading with high chloride and organics, followed by the BB air mass, which was more contaminated than AS, with a higher organic fraction and nitrate. The primary sources were identified as biomass-burning, thermal power plant emissions, industrial emissions, and vehicular emissions. The average hygroscopicity parameter (κ), calculated by the mixing rule, was approximately 0.3 (varying between 0.13 and 0.77) for all the air masses (0.32±0.06 for AS, 0.31±0.06 for BB, and 0.32±0.10 for SA). The diurnal variations in κ were impacted by the chemical properties and thus source activities. The total, Aitken, and accumulation mode number concentrations were higher for SA, followed by BB and AS. The mean values of estimated CCN number concentration (NCCN; 3669–28926 cm−3) and the activated fraction (af; 0.19–0.87), for supersaturations varying from 0.1 % to 0.8 %, also showed the same trend, implying that these were highest in SA, followed by those in BB and then those in AS. The size turned out to be more important than chemical composition directly, and the NCCN was governed by either the Aitken or accumulation modes, depending upon the supersaturation (SS) and critical diameter (Dc). af was governed mainly by the geometric mean diameter (GMD), and such a high af (0.71±0.14 for the most dominant sub-branch of the SA air mass – R1 – at 0.4 % SS) has not been seen anywhere in the world for a continental site. The high af was a consequence of very low Dc (25–130 nm, for SS ranging from 0.1 % to 0.8 %) observed for Delhi. Indirectly, the chemical properties also impacted CCN and af by impacting the diurnal patterns of Aitken and accumulation modes, κ and Dc. The high-hygroscopic nature of aerosols, high NCCN, and high af can severely impact the precipitation patterns of the Indian monsoon in Delhi, impact the radiation budget, and have indirect effects and need to be investigated to quantify this impact.

scholarly journals Air mass physio-chemical characteristics over New Delhi: Impacts on aerosol hygroscopicity and CCN formation

2019 ◽  
Author(s):  
Zainab Arub ◽  
Sahil Bhandari ◽  
Shahzad Gani ◽  
Joshua S. Apte ◽  
Lea Hildebrandt Ruiz ◽  
...  
Keyword(s):  
Geometric Mean ◽  
Thermal Power ◽  
Chemical Properties ◽  
Critical Diameter ◽  
Radiation Budget ◽  
Aerosol Composition ◽  
Time Resolved ◽  
Air Mass ◽  
Mean Values ◽  
Air Masses

Abstract. This work presents for the first time long term and time-resolved estimates of hygroscopicty parameter (κ) and CCN for Delhi, a megacity that is subjected to high local anthropogenic emissions and long-range transport of pollutants. As a part of the Delhi Aerosol Supersite (DAS) campaign, characterisation of aerosol composition and size distribution were conducted from January 2017–March 2018. Air masses originating from the Arabian Sea (AS), Bay of Bengal (BB) and South Asia (SA) exhibited distinct characteristics of time-resolved sub-micron non-refractory PM1 (NRPM1) species, size distributions, and CCN number concentrations. SA air mass had the highest NRPM1 loading with high chloride and organics followed by BB air mass which was relatively more contaminated than AS with a higher organic fraction and nitrate. The primary sources were identified as biomass-burning, thermal power plant emissions, industrial and vehicular emissions. The average hygroscopicty parameter (κ), calculated by the mixing rule was ~ 0.3 (varying between 0.13 and 0.77) for all the air masses (0.32 ± 0.06 for AS, 0.31 ± 0.06 for BB and 0.32 ± 0.10 for SA). The diurnal variations of κ were impacted by the chemical properties and thus source activities. The total, Aitken, and Accumulation mode number concentrations were higher for SA, followed by BB and AS. The mean values of estimated CCN number concentration (NCCN, 3669–28 926 cm−3) and the activated fraction (af, 0.19–0.87) for supersaturations varying from 0.1–0.8 % also showed the same trend (SA > BB > AS). The size turned out to be more important than chemical composition directly, and the NCCN was governed by either the Aitken or Accumulation modes depending upon the supersaturation (SS) and critical diameter (Dc). The af was governed mainly by the Geometric Mean Diameter (GMD), and such a high af (0.71 ± 0.14 for the most dominant sub-branch of SA air mass (R1) at 0.4 % SS) has not been seen anywhere in the world. The high af was a consequence of very low Dc (25–130 nm for SS ranging from 0.1 %–0.8 %) observed for Delhi. Indirectly, the chemical properties also impacted CCN and af by impacting the diurnal patterns of Aitken and accumulation modes, κ and Dc. The high hygroscopic nature of aerosols, high NCCN and high af can severely impact the precipitation patterns of the Indian Monsoon in Delhi, the radiation budget and the indirect effect and need to be investigated to quantify the impacts.

scholarly journals Aerosol Optical Extinction during the Front Range Air Pollution and Photochemistry Éxperiment (FRAPPÉ) 2014 Summertime Field Campaign, Colorado U.S.A.

2016 ◽  
Author(s):  
Justin H. Dingle ◽  
Kennedy Vu ◽  
Roya Bahreini ◽  
Eric C. Apel ◽  
Teresa L. Campos ◽  
...  
Keyword(s):  
Air Pollution ◽  
Light Extinction ◽  
Organic Nitrate ◽  
Front Range ◽  
Aerosol Composition ◽  
Optical Extinction ◽  
Air Mass ◽  
Air Masses ◽  
Aerosol Optical Extinction ◽  
Air Mass Types

Abstract. Summertime aerosol optical extinction (βext) was measured in the Colorado Front Range and Denver Metropolitan Area as part of the Front Range Air Pollution and Photochemistry Experiment (FRAPPÉ) campaign during July–August 2014. An Aerodyne Cavity Attenuated Phase Shift particle light extinction monitor (CAPS-PMex) was deployed to measure dry, βext of submicron aerosols at λ = 632 nm at 1 Hz. Data from a suite of gas-phase instrumentation were used to interpret βext behavior under various categories of air masses and sources. Extinction enhancement ratios relative to CO (Δβext/ΔCO) were significantly increased in highly aged air masses compared to fresh air masses by 50–60 %. The resulting increase in Δβext/ΔCO under highly aged air masses was accompanied by formation of secondary organic aerosols (SOA). In addition, the impacts of aerosol composition on βext in air masses under the influence of urban, natural oil and gas operations (O&G), and agriculture and livestock operations were evaluated. Estimated non-refractory mass extinction efficiency (MEE) values for different air mass types ranged from 1.83–3.30 m2 g−1, with the minimum and maximum values observed in agriculture and urban + O&G influenced air masses, respectively. The mass distribution for organic, nitrate, and sulfate aerosols presented distinct profiles in different air mass types. During Aug. 11–12, regional influence of a biomass burning event was observed, increasing the background βext by 10–15 Mm−1 and the estimated MEE and Δβext/ΔCO values in the Front Range.

scholarly journals Reactive Halogens in the Marine Boundary Layer (RHaMBLe): the tropical North Atlantic experiments

2010 ◽  
Vol 10 (3) ◽  
pp. 1031-1055 ◽  
Author(s):  
J. D. Lee ◽  
G. McFiggans ◽  
J. D. Allan ◽  
A. R. Baker ◽  
S. M. Ball ◽  
...  
Keyword(s):  
Boundary Layer ◽  
North Atlantic ◽  
Marine Boundary Layer ◽  
Cape Verde ◽  
Aerosol Composition ◽  
Air Mass ◽  
Mixing Ratios ◽  
Tropical North Atlantic ◽  
Halogen Species

Abstract. The NERC UK SOLAS-funded Reactive Halogens in the Marine Boundary Layer (RHaMBLe) programme comprised three field experiments. This manuscript presents an overview of the measurements made within the two simultaneous remote experiments conducted in the tropical North Atlantic in May and June 2007. Measurements were made from two mobile and one ground-based platforms. The heavily instrumented cruise D319 on the RRS Discovery from Lisbon, Portugal to São Vicente, Cape Verde and back to Falmouth, UK was used to characterise the spatial distribution of boundary layer components likely to play a role in reactive halogen chemistry. Measurements onboard the ARSF Dornier aircraft were used to allow the observations to be interpreted in the context of their vertical distribution and to confirm the interpretation of atmospheric structure in the vicinity of the Cape Verde islands. Long-term ground-based measurements at the Cape Verde Atmospheric Observatory (CVAO) on São Vicente were supplemented by long-term measurements of reactive halogen species and characterisation of additional trace gas and aerosol species during the intensive experimental period. This paper presents a summary of the measurements made within the RHaMBLe remote experiments and discusses them in their meteorological and chemical context as determined from these three platforms and from additional meteorological analyses. Air always arrived at the CVAO from the North East with a range of air mass origins (European, Atlantic and North American continental). Trace gases were present at stable and fairly low concentrations with the exception of a slight increase in some anthropogenic components in air of North American origin, though NOx mixing ratios during this period remained below 20 pptv (note the non-IUPAC adoption in this manuscript of pptv and ppbv, equivalent to pmol mol−1 and nmol mol−1 to reflect common practice). Consistency with these air mass classifications is observed in the time series of soluble gas and aerosol composition measurements, with additional identification of periods of slightly elevated dust concentrations consistent with the trajectories passing over the African continent. The CVAO is shown to be broadly representative of the wider North Atlantic marine boundary layer; measurements of NO, O3 and black carbon from the ship are consistent with a clean Northern Hemisphere marine background. Aerosol composition measurements do not indicate elevated organic material associated with clean marine air. Closer to the African coast, black carbon and NO levels start to increase, indicating greater anthropogenic influence. Lower ozone in this region is possibly associated with the increased levels of measured halocarbons, associated with the nutrient rich waters of the Mauritanian upwelling. Bromide and chloride deficits in coarse mode aerosol at both the CVAO and on D319 and the continuous abundance of inorganic gaseous halogen species at CVAO indicate significant reactive cycling of halogens. Aircraft measurements of O3 and CO show that surface measurements are representative of the entire boundary layer in the vicinity both in diurnal variability and absolute levels. Above the inversion layer similar diurnal behaviour in O3 and CO is observed at lower mixing ratios in the air that had originated from south of Cape Verde, possibly from within the ITCZ. ECMWF calculations on two days indicate very different boundary layer depths and aircraft flights over the ship replicate this, giving confidence in the calculated boundary layer depth.

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

2012 ◽  
Vol 12 (1) ◽  
pp. 1215-1265 ◽  
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.

scholarly journals Reactive Halogens in the Marine Boundary Layer (RHaMBLe): the tropical North Atlantic experiments

2009 ◽  
Vol 9 (5) ◽  
pp. 21717-21783 ◽  
Author(s):  
J. D. Lee ◽  
G. McFiggans ◽  
J. D. Allan ◽  
A. R. Baker ◽  
S. M. Ball ◽  
...  
Keyword(s):  
Boundary Layer ◽  
North Atlantic ◽  
Marine Boundary Layer ◽  
Cape Verde ◽  
Aerosol Composition ◽  
Air Mass ◽  
Mixing Ratios ◽  
Tropical North Atlantic ◽  
Halogen Species

Abstract. The NERC UK SOLAS-funded Reactive Halogens in the Marine Boundary Layer (RHaMBLe) programme comprised three field experiments. This manuscript presents an overview of the measurements made within the two simultaneous remote experiments conducted in the tropical North Atlantic in May and June 2007. Measurements were made from two mobile and one ground-based platforms. The heavily instrumented cruise D319 on the RRS Discovery from Lisbon, Portugal to São Vicente, Cape Verde and back to Falmouth, UK was used to characterise the spatial distribution of boundary layer components likely to play a role in reactive halogen chemistry. Measurements onboard the ARSF Dornier aircraft were used to allow the observations to be interpreted in the context of their vertical distribution and to confirm the interpretation of atmospheric structure in the vicinity of the Cape Verde islands. Long-term ground-based measurements at the Cape Verde Atmospheric Observatory (CVAO) on São Vicente were supplemented by long-term measurements of reactive halogen species and characterisation of additional trace gas and aerosol species during the intensive experimental period. This paper presents a summary of the measurements made within the RHaMBLe remote experiments and discusses them in their meteorological and chemical context as determined from these three platforms and from additional meteorological analyses. Air always arrived at the CVAO from the North East with a range of air mass origins (European, Atlantic and North American continental). Trace gases were present at stable and fairly low concentrations with the exception of a slight increase in some anthropogenic components in air of North American origin, though NOx mixing ratios during this period remained below 20 pptv. Consistency with these air mass classifications is observed in the time series of soluble gas and aerosol composition measurements, with additional identification of periods of slightly elevated dust concentrations consistent with the trajectories passing over the African continent. The CVAO is shown to be broadly representative of the wider North Atlantic marine boundary layer; measurements of NO, O3 and black carbon from the ship are consistent with a clean Northern Hemisphere marine background. Aerosol composition measurements do not indicate elevated organic material associated with clean marine air. Closer to the African coast, black carbon and NO levels start to increase, indicating greater anthropogenic influence. Lower ozone in this region is possibly associated with the increased levels of measured halocarbons, associated with the nutrient rich waters of the Mauritanian upwelling. Bromide and chloride deficits in coarse mode aerosol at both the CVAO and on D319 and the continuous abundance of inorganic gaseous halogen species at CVAO indicate significant reactive cycling of halogens. Aircraft measurements of O3 and CO show that surface measurements are representative of the entire boundary layer in the vicinity both in diurnal variability and absolute levels. Above the inversion layer similar diurnal behaviour in O3 and CO is observed at lower mixing ratios in the air that had originated from south of Cape Verde, possibly from within the ITCZ. ECMWF calculations on two days indicate very different boundary layer depths and aircraft flights over the ship replicate this, giving confidence in the calculated boundary layer depth.

scholarly journals Aerosol optical extinction during the Front Range Air Pollution and Photochemistry Éxperiment (FRAPPÉ) 2014 summertime field campaign, Colorado, USA

2016 ◽  
Vol 16 (17) ◽  
pp. 11207-11217 ◽  
Author(s):  
Justin H. Dingle ◽  
Kennedy Vu ◽  
Roya Bahreini ◽  
Eric C. Apel ◽  
Teresa L. Campos ◽  
...  
Keyword(s):  
Air Pollution ◽  
Light Extinction ◽  
Organic Nitrate ◽  
Front Range ◽  
Aerosol Composition ◽  
Optical Extinction ◽  
Air Mass ◽  
Air Masses ◽  
Aerosol Optical Extinction ◽  
Air Mass Types

Abstract. Summertime aerosol optical extinction (βext) was measured in the Colorado Front Range and Denver metropolitan area as part of the Front Range Air Pollution and Photochemistry Éxperiment (FRAPPÉ) campaign during July–August 2014. An Aerodyne cavity attenuated phase shift particle light extinction monitor (CAPS-PMex) was deployed to measure βext (at average relative humidity of 20 ± 7 %) of submicron aerosols at λ = 632 nm at 1 Hz. Data from a suite of gas-phase instrumentation were used to interpret βext behavior in various categories of air masses and sources. Extinction enhancement ratios relative to CO (Δβext ∕ ΔCO) were higher in aged urban air masses compared to fresh air masses by  ∼  50 %. The resulting increase in Δβext ∕ ΔCO for highly aged air masses was accompanied by formation of secondary organic aerosols (SOAs). In addition, the impacts of aerosol composition on βext in air masses under the influence of urban, natural oil and gas operations (O&G), and agriculture and livestock operations were evaluated. Estimated non-refractory mass extinction efficiency (MEE) values for different air mass types ranged from 1.51 to 2.27 m2 g−1, with the minimum and maximum values observed in urban and agriculture-influenced air masses, respectively. The mass distribution for organic, nitrate, and sulfate aerosols presented distinct profiles in different air mass types. During 11–12 August, regional influence of a biomass burning event was observed, increasing the background βext and estimated MEE values in the Front Range.

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