scholarly journals Quantification of chemical and physical processes influencing ozone during long-range transport using a trajectory ensemble

2012 ◽  
Vol 12 (1) ◽  
pp. 3019-3074 ◽  
Author(s):  
M. Cain ◽  
J. Methven ◽  
E. J. Highwood
Keyword(s):  
Long Range ◽  
Long Range Transport ◽  
Mass Composition ◽  
Physical Parameters ◽  
Physical Processes ◽  
Air Mass ◽  
Mixing Ratios ◽  
The North ◽  
Range Transport ◽  
Physical Processing

Abstract. During long-range transport, many distinct processes – including photochemistry, deposition, emissions and mixing – contribute to the transformation of air mass composition. Partitioning the effects of different processes can be useful when considering the sensitivity of chemical transformation to, for example, a changing environment or anthropogenic influence. However, transformation is not observed directly, since mixing ratios are measured, and models must be used to relate changes to processes. Here, four cases from the ITCT-Lagrangian 2004 experiment are studied. In each case, aircraft intercepted an air mass several times during transport over the North Atlantic, providing a unique dataset and quantifying the net changes in composition from all processes acting. A new framework is presented to deconstruct the change in O3 mixing ratio (ΔO3) into its component processes, which were not measured directly, taking into account the uncertainty in measurements, initial air mass variability and its time evolution. The results show that the net chemical processing (ΔO3chem) over the whole simulation is greater than net physical processing (ΔO3phys) in all cases. This is in part explained by cancellation effects associated with mixing. In contrast, each case is in a regime of either photochemical destruction (lower tropospheric transport) or production (an upper tropospheric biomass burning case). However, physical processes influence O3 indirectly through addition or removal of precursor gases, so that changes to physical parameters in a model can have a larger effect on ΔO3chem than ΔO3phys. Despite its smaller magnitude, the physical processing distinguishes the lower tropospheric export cases, since the photochemical O3 change is −5ppbv per day in all three cases. Processing is quantified using a Lagrangian photochemical model with a novel method for simulating mixing through an ensemble of trajectories and a background profile that evolves with them. The model is able to simulate the magnitude and variability of the observations (of O3, CO, NOy and some hydrocarbons) and is consistent with the time-average OH following air-masses inferred from hydrocarbon measurements alone (by Arnold et al., 2007). Therefore, it is a useful new method to simulate air mass evolution and variability, and its sensivity to process parameters.

scholarly journals Quantification of chemical and physical processes influencing ozone during long-range transport using a trajectory ensemble

2012 ◽  
Vol 12 (15) ◽  
pp. 7015-7039 ◽  
Author(s):  
M. Cain ◽  
J. Methven ◽  
E. J. Highwood
Keyword(s):  
Long Range ◽  
Long Range Transport ◽  
Mass Composition ◽  
Physical Parameters ◽  
Physical Processes ◽  
Air Mass ◽  
Mixing Ratios ◽  
The North ◽  
Range Transport ◽  
Physical Processing

Abstract. During long-range transport, many distinct processes – including photochemistry, deposition, emissions and mixing – contribute to the transformation of air mass composition. Partitioning the effects of different processes can be useful when considering the sensitivity of chemical transformation to, for example, a changing environment or anthropogenic influence. However, transformation is not observed directly, since mixing ratios are measured, and models must be used to relate changes to processes. Here, four cases from the ITCT-Lagrangian 2004 experiment are studied. In each case, aircraft intercepted a distinct air mass several times during transport over the North Atlantic, providing a unique dataset and quantifying the net changes in composition from all processes. A new framework is presented to deconstruct the change in O3 mixing ratio (Δ O3) into its component processes, which were not measured directly, taking into account the uncertainty in measurements, initial air mass variability and its time evolution. The results show that the net chemical processing (Δ O3chem) over the whole simulation is greater than net physical processing (Δ O3phys) in all cases. This is in part explained by cancellation effects associated with mixing. In contrast, each case is in a regime of either net photochemical destruction (lower tropospheric transport) or production (an upper tropospheric biomass burning case). However, physical processes influence O3 indirectly through addition or removal of precursor gases, so that changes to physical parameters in a model can have a larger effect on Δ O3chem than Δ O3phys. Despite its smaller magnitude, the physical processing distinguishes the lower tropospheric export cases, since the net photochemical O3 change is −5 ppbv per day in all three cases. Processing is quantified using a Lagrangian photochemical model with a novel method for simulating mixing through an ensemble of trajectories and a background profile that evolves with them. The model is able to simulate the magnitude and variability of the observations (of O3, CO, NOy and some hydrocarbons) and is consistent with the time-average OH following air-masses inferred from hydrocarbon measurements alone (by Arnold et al., 2007). Therefore, it is a useful new method to simulate air mass evolution and variability, and its sensitivity to process parameters.

scholarly journals Transport and fate of hexachlorocyclohexanes in the oceanic air and surface seawater

2011 ◽  
Vol 8 (3) ◽  
pp. 5537-5562 ◽  
Author(s):  
Z. Xie ◽  
B. P. Koch ◽  
A. Möller ◽  
R. Sturm ◽  
R. Ebinghaus
Keyword(s):  
Southern Ocean ◽  
Long Range ◽  
Water Exchange ◽  
Exchange Process ◽  
Lower Atmosphere ◽  
Long Range Transport ◽  
Surface Seawater ◽  
The North ◽  
Range Transport ◽  
Long Term Trends

Abstract. Hexachlorocyclohexanes (HCHs) are ubiquitous organic pollutants derived from pesticide application. They are subject to long-range transport, persistent in the environment, and capable of accumulation in biota. Shipboard measurements of HCH isomers (α-, γ- and β-HCH) in surface seawater and boundary layer atmospheric samples were conducted in the Atlantic and the Southern Ocean in October to December of 2008. ΣHCHs concentrations (the sum of α-, γ- and β-HCH) in the lower atmosphere ranged from 11.8 to 36.9 pg m−3 (mean: 26.6 ± 11.0 pg m−3) in the Northern Hemisphere (NH), and from 1.5 to 4.0 pg m−3 (mean: 2.8 ± 1.1 pg m−3) in the Southern Hemisphere (SH), respectively. Water concentrations were: α-HCH 0.33–46.8 pg l−1, γ-HCH 0.02–33.2 pg l−1 and β-HCH 0.11–2 pg l−1. HCH concentrations decreased from the North Atlantic to the Southern Ocean, indicating historical use of HCHs in the NH. Spatial distribution showed increasing concentrations from the equator towards North and South latitudes illustrating the concept of cold condensation and less interhemispheric mixing process. In comparison to concentrations measured in 1987–1999/2000, gaseous HCHs were slightly lower, while dissolved HCHs decreased by factor of 2–3 orders of magnitude. Air-water exchange gradients suggested net deposition for α-HCH (mean: 3759 pg m−2 day−1) and γ-HCH (mean: 1987 pg m−2 day−1), whereas β-HCH varied between equilibrium (volatilization: <0–12 pg m−2 day−1) and net deposition (range: 6–687 pg m−2 day−1), indicating a multi-hopper transport behavior. Climate change may significantly accelerate the releasing process of "old" HCHs from continental storage (e.g. soil, vegetation and high mountains) and drive long-range transport from sources to deposition in the open oceans. Biological productivities may interfere with the air-water exchange process as well. Consequently, further investigation is necessary to elucidate the long term trends and the biogeochemical turnover of HCHs in the oceanic environment.

scholarly journals Lagrangian formation pathways of moist anomalies in the trade-wind region during the dry season: two case studies from EUREC<sup>4</sup>A

2021 ◽  
Author(s):  
Leonie Villiger ◽  
Heini Wernli ◽  
Maxi Boettcher ◽  
Martin Hagen ◽  
Franziska Aemisegger
Keyword(s):  
Long Range ◽  
North Atlantic ◽  
Large Scale ◽  
Cold Front ◽  
Trade Wind ◽  
Long Range Transport ◽  
The North ◽  
Range Transport ◽  
The North Atlantic ◽  
The Tropics

Abstract. Shallow clouds in the trade-wind region over the North Atlantic contribute substantially to the global radiative budget. In the vicinity of the Caribbean island Barbados, they appear in different mesoscale organisation patterns with distinct net cloud radiative effects (CRE). Cloud formation processes in this region are typically controlled by the prevailing large-scale subsidence. However, occasionally weather systems from remote origin cause significant disturbances. This study investigates the complex cloud-circulation interactions during the field campaign EUREC4A (Elucidate the Couplings Between Clouds, Convection and Circulation) from 16 January to 20 February 2020, using a combination of Eulerian and Lagrangian diagnostics. Based on observations and ERA5 reanalyses, we identify the relevant processes and characterise the formation pathways of two moist anomalies above the Barbados Cloud Observatory (BCO), one in the lower (~1000–650 hPa) and one in the middle troposphere (~650–300 hPa). These moist anomalies are associated with strongly negative CRE values and with contrasting long-range transport processes from the extratropics and the tropics, respectively. The low-level moist anomaly is characterised by an unusually thick cloud layer, high precipitation totals and a strongly negative CRE. Its formation is connected to an “extratropical dry intrusion” (EDI) that interacts with a trailing cold front. A quasi-climatological (2010–2020) analysis reveals that EDIs lead to different conditions at the BCO depending on how they interact with the associated cold front. Based on this climatology, we discuss the relevance of the strong large-scale forcing by EDIs for the low-cloud patterns near the BCO and the related CRE. The second case study about the mid-tropospheric moist anomaly is associated with an extended and persistent mixed-phase shelf cloud and the lowest daily CRE value observed during the campaign. Its formation is linked to “tropical mid-level detrainment” (TMD), which refers to detrainment from tropical deep convection near the melting layer. The quasi-climatological analysis shows that TMDs consistently lead to mid-tropospheric moist anomalies over the BCO and that the detrainment height controls the magnitude of the anomaly. However, no systematic relationship was found between the amplitude of this mid-tropospheric moist anomaly and the CRE at the BCO. Overall, this study reveals the important impact of the long-range transport, driven by dynamical processes either in the extratropics or the tropics, on the variability of the vertical structure of moisture and clouds, and on the resulting CRE in the North Atlantic winter trades.

Diurnal variation of OH radical and hydrocarbons in a polluted air mass during long-range transport in central Japan

1992 ◽  
Vol 26 (15) ◽  
pp. 2835-2844 ◽  
Author(s):  
Hikaru Satsumabayashi ◽  
Hidemi Kurita ◽  
Young-Soo Chang ◽  
Gregory R. Carmichael ◽  
Hiromasa Ueda
Keyword(s):  
Diurnal Variation ◽  
Long Range ◽  
Long Range Transport ◽  
Oh Radical ◽  
Central Japan ◽  
Air Mass ◽  
Range Transport

scholarly journals Effect of Long-range Transport of Air Mass on the Ionic Components in Radiation Fog in Northern Japan

2004 ◽  
Vol 20 (1) ◽  
pp. 69-72 ◽  
Author(s):  
Nobuaki OGAWA ◽  
Keiji YOSHIMURA ◽  
Ryoei KIKUCHI ◽  
Tetsuya ADZUHATA ◽  
Toru OZEKI ◽  
...  
Keyword(s):  
Long Range ◽  
Long Range Transport ◽  
Radiation Fog ◽  
Air Mass ◽  
Range Transport ◽  
Ionic Components ◽  
Northern Japan

scholarly journals Long-term chemical characterization of tropical and marine aerosols at the Cape Verde Atmospheric Observatory (CVAO) from 2007 to 2011

2014 ◽  
Vol 14 (17) ◽  
pp. 8883-8904 ◽  
Author(s):  
K. W. Fomba ◽  
K. Müller ◽  
D. van Pinxteren ◽  
L. Poulain ◽  
M. van Pinxteren ◽  
...  
Keyword(s):  
Long Range ◽  
Mineral Dust ◽  
Chemical Characterization ◽  
Sea Salt ◽  
Saharan Dust ◽  
Long Range Transport ◽  
Air Mass ◽  
Aerosol Mass ◽  
Range Transport

Abstract. The first long-term aerosol sampling and chemical characterization results from measurements at the Cape Verde Atmospheric Observatory (CVAO) on the island of São Vicente are presented and are discussed with respect to air mass origin and seasonal trends. In total 671 samples were collected using a high-volume PM10 sampler on quartz fiber filters from January 2007 to December 2011. The samples were analyzed for their aerosol chemical composition, including their ionic and organic constituents. Back trajectory analyses showed that the aerosol at CVAO was strongly influenced by emissions from Europe and Africa, with the latter often responsible for high mineral dust loading. Sea salt and mineral dust dominated the aerosol mass and made up in total about 80% of the aerosol mass. The 5-year PM10 mean was 47.1 &amp;pm; 55.5 μg m−2, while the mineral dust and sea salt means were 27.9 &amp;pm; 48.7 and 11.1 &amp;pm; 5.5 μg m−2, respectively. Non-sea-salt (nss) sulfate made up 62% of the total sulfate and originated from both long-range transport from Africa or Europe and marine sources. Strong seasonal variation was observed for the aerosol components. While nitrate showed no clear seasonal variation with an annual mean of 1.1 &amp;pm; 0.6 μg m−3, the aerosol mass, OC (organic carbon) and EC (elemental carbon), showed strong winter maxima due to strong influence of African air mass inflow. Additionally during summer, elevated concentrations of OM were observed originating from marine emissions. A summer maximum was observed for non-sea-salt sulfate and was connected to periods when air mass inflow was predominantly of marine origin, indicating that marine biogenic emissions were a significant source. Ammonium showed a distinct maximum in spring and coincided with ocean surface water chlorophyll a concentrations. Good correlations were also observed between nss-sulfate and oxalate during the summer and winter seasons, indicating a likely photochemical in-cloud processing of the marine and anthropogenic precursors of these species. High temporal variability was observed in both chloride and bromide depletion, differing significantly within the seasons, air mass history and Saharan dust concentration. Chloride (bromide) depletion varied from 8.8 &amp;pm; 8.5% (62 &amp;pm; 42%) in Saharan-dust-dominated air mass to 30 \\textpm 12% (87 &amp;pm; 11%) in polluted Europe air masses. During summer, bromide depletion often reached 100% in marine as well as in polluted continental samples. In addition to the influence of the aerosol acidic components, photochemistry was one of the main drivers of halogenide depletion during the summer; while during dust events, displacement reaction with nitric acid was found to be the dominant mechanism. Positive matrix factorization (PMF) analysis identified three major aerosol sources: sea salt, aged sea salt and long-range transport. The ionic budget was dominated by the first two of these factors, while the long-range transport factor could only account for about 14% of the total observed ionic mass.

Sign in / Sign up

Export Citation Format

Share Document