Ambient aerosol properties in the remote atmosphere from global-scale in situ measurements
In situ measurements of aerosol microphysical, chemical, and optical properties were made during global-scale flights from 2016–2018 as part of the Atmospheric Tomography Mission (ATom). The NASA DC-8 aircraft flew from ∼ 84 ∘ N to ∼ 86 ∘ S latitude over the Pacific, Atlantic, Arctic, and Southern o...
Published in: | Atmospheric Chemistry and Physics |
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2021
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Online Access: | https://doi.org/10.5194/acp-21-15023-2021 https://acp.copernicus.org/articles/21/15023/2021/ |
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In situ measurements of aerosol microphysical, chemical, and optical properties were made during global-scale flights from 2016–2018 as part of the Atmospheric Tomography Mission (ATom). The NASA DC-8 aircraft flew from ∼ 84 ∘ N to ∼ 86 ∘ S latitude over the Pacific, Atlantic, Arctic, and Southern oceans while profiling nearly continuously between altitudes of ∼ 160 m and ∼ 12 km. These global circuits were made once each season. Particle size distributions measured in the aircraft cabin at dry conditions and with an underwing probe at ambient conditions were combined with bulk and single-particle composition observations and measurements of water vapor, pressure, and temperature to estimate aerosol hygroscopicity and hygroscopic growth factors and calculate size distributions at ambient relative humidity. These reconstructed, composition-resolved ambient size distributions were used to estimate intensive and extensive aerosol properties, including single-scatter albedo, the asymmetry parameter, extinction, absorption, Ångström exponents, and aerosol optical depth (AOD) at several wavelengths, as well as cloud condensation nuclei (CCN) concentrations at fixed supersaturations and lognormal fits to four modes. Dry extinction and absorption were compared with direct in situ measurements, and AOD derived from the extinction profiles was compared with remotely sensed AOD measurements from the ground-based Aerosol Robotic Network (AERONET); this comparison showed no substantial bias. The purpose of this work is to describe the methodology by which ambient aerosol properties are estimated from the in situ measurements, provide statistical descriptions of the aerosol characteristics of different remote air mass types, examine the contributions to AOD from different aerosol types in different air masses, and provide an entry point to the ATom aerosol database. The contributions of different aerosol types (dust, sea salt, biomass burning, etc.) to AOD generally align with expectations based on location of the profiles relative to continental sources of aerosols, with sea salt and aerosol water dominating the column extinction in most remote environments and dust and biomass burning (BB) particles contributing substantially to AOD, especially downwind of the African continent. Contributions of dust and BB aerosols to AOD were also significant in the free troposphere over the North Pacific. Comparisons of lognormally fitted size distribution parameters to values in the Optical Properties of Aerosols and Clouds (OPAC) database commonly used in global models show significant differences in the mean diameters and standard deviations for accumulation-mode particles and coarse-mode dust. In contrast, comparisons of lognormal parameters derived from the ATom data with previously published shipborne measurements in the remote marine boundary layer show general agreement. The dataset resulting from this work can be used to improve global-scale representation of climate-relevant aerosol properties in remote air masses through comparison with output from global models and assumptions used in retrievals of aerosol properties from both ground-based and satellite remote sensing. |
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author |
Brock, Charles A. Froyd, Karl D. Dollner, Maximilian Williamson, Christina J. Schill, Gregory Murphy, Daniel M. Wagner, Nicholas J. Kupc, Agnieszka Jimenez, Jose L. Campuzano-Jost, Pedro Nault, Benjamin A. Schroder, Jason C. Day, Douglas A. Price, Derek J. Weinzierl, Bernadett Schwarz, Joshua P. Katich, Joseph M. Wang, Siyuan Zeng, Linghan Weber, Rodney Dibb, Jack Scheuer, Eric Diskin, Glenn S. DiGangi, Joshua P. Bui, ThaoPaul Dean-Day, Jonathan M. Thompson, Chelsea R. Peischl, Jeff Ryerson, Thomas B. Bourgeois, Ilann Daube, Bruce C. Commane, Róisín Wofsy, Steven C. |
spellingShingle |
Brock, Charles A. Froyd, Karl D. Dollner, Maximilian Williamson, Christina J. Schill, Gregory Murphy, Daniel M. Wagner, Nicholas J. Kupc, Agnieszka Jimenez, Jose L. Campuzano-Jost, Pedro Nault, Benjamin A. Schroder, Jason C. Day, Douglas A. Price, Derek J. Weinzierl, Bernadett Schwarz, Joshua P. Katich, Joseph M. Wang, Siyuan Zeng, Linghan Weber, Rodney Dibb, Jack Scheuer, Eric Diskin, Glenn S. DiGangi, Joshua P. Bui, ThaoPaul Dean-Day, Jonathan M. Thompson, Chelsea R. Peischl, Jeff Ryerson, Thomas B. Bourgeois, Ilann Daube, Bruce C. Commane, Róisín Wofsy, Steven C. Ambient aerosol properties in the remote atmosphere from global-scale in situ measurements |
author_facet |
Brock, Charles A. Froyd, Karl D. Dollner, Maximilian Williamson, Christina J. Schill, Gregory Murphy, Daniel M. Wagner, Nicholas J. Kupc, Agnieszka Jimenez, Jose L. Campuzano-Jost, Pedro Nault, Benjamin A. Schroder, Jason C. Day, Douglas A. Price, Derek J. Weinzierl, Bernadett Schwarz, Joshua P. Katich, Joseph M. Wang, Siyuan Zeng, Linghan Weber, Rodney Dibb, Jack Scheuer, Eric Diskin, Glenn S. DiGangi, Joshua P. Bui, ThaoPaul Dean-Day, Jonathan M. Thompson, Chelsea R. Peischl, Jeff Ryerson, Thomas B. Bourgeois, Ilann Daube, Bruce C. Commane, Róisín Wofsy, Steven C. |
author_sort |
Brock, Charles A. |
title |
Ambient aerosol properties in the remote atmosphere from global-scale in situ measurements |
title_short |
Ambient aerosol properties in the remote atmosphere from global-scale in situ measurements |
title_full |
Ambient aerosol properties in the remote atmosphere from global-scale in situ measurements |
title_fullStr |
Ambient aerosol properties in the remote atmosphere from global-scale in situ measurements |
title_full_unstemmed |
Ambient aerosol properties in the remote atmosphere from global-scale in situ measurements |
title_sort |
ambient aerosol properties in the remote atmosphere from global-scale in situ measurements |
publishDate |
2021 |
url |
https://doi.org/10.5194/acp-21-15023-2021 https://acp.copernicus.org/articles/21/15023/2021/ |
geographic |
Arctic Pacific |
geographic_facet |
Arctic Pacific |
genre |
Aerosol Robotic Network albedo Arctic Atlantic Arctic Atlantic-Arctic |
genre_facet |
Aerosol Robotic Network albedo Arctic Atlantic Arctic Atlantic-Arctic |
op_source |
eISSN: 1680-7324 |
op_relation |
doi:10.5194/acp-21-15023-2021 https://acp.copernicus.org/articles/21/15023/2021/ |
op_doi |
https://doi.org/10.5194/acp-21-15023-2021 |
container_title |
Atmospheric Chemistry and Physics |
container_volume |
21 |
container_issue |
19 |
container_start_page |
15023 |
op_container_end_page |
15063 |
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1766044556082544640 |
spelling |
ftcopernicus:oai:publications.copernicus.org:acp93184 2023-05-15T13:07:16+02:00 Ambient aerosol properties in the remote atmosphere from global-scale in situ measurements Brock, Charles A. Froyd, Karl D. Dollner, Maximilian Williamson, Christina J. Schill, Gregory Murphy, Daniel M. Wagner, Nicholas J. Kupc, Agnieszka Jimenez, Jose L. Campuzano-Jost, Pedro Nault, Benjamin A. Schroder, Jason C. Day, Douglas A. Price, Derek J. Weinzierl, Bernadett Schwarz, Joshua P. Katich, Joseph M. Wang, Siyuan Zeng, Linghan Weber, Rodney Dibb, Jack Scheuer, Eric Diskin, Glenn S. DiGangi, Joshua P. Bui, ThaoPaul Dean-Day, Jonathan M. Thompson, Chelsea R. Peischl, Jeff Ryerson, Thomas B. Bourgeois, Ilann Daube, Bruce C. Commane, Róisín Wofsy, Steven C. 2021-10-08 application/pdf https://doi.org/10.5194/acp-21-15023-2021 https://acp.copernicus.org/articles/21/15023/2021/ eng eng doi:10.5194/acp-21-15023-2021 https://acp.copernicus.org/articles/21/15023/2021/ eISSN: 1680-7324 Text 2021 ftcopernicus https://doi.org/10.5194/acp-21-15023-2021 2021-10-11T16:22:28Z In situ measurements of aerosol microphysical, chemical, and optical properties were made during global-scale flights from 2016–2018 as part of the Atmospheric Tomography Mission (ATom). The NASA DC-8 aircraft flew from ∼ 84 ∘ N to ∼ 86 ∘ S latitude over the Pacific, Atlantic, Arctic, and Southern oceans while profiling nearly continuously between altitudes of ∼ 160 m and ∼ 12 km. These global circuits were made once each season. Particle size distributions measured in the aircraft cabin at dry conditions and with an underwing probe at ambient conditions were combined with bulk and single-particle composition observations and measurements of water vapor, pressure, and temperature to estimate aerosol hygroscopicity and hygroscopic growth factors and calculate size distributions at ambient relative humidity. These reconstructed, composition-resolved ambient size distributions were used to estimate intensive and extensive aerosol properties, including single-scatter albedo, the asymmetry parameter, extinction, absorption, Ångström exponents, and aerosol optical depth (AOD) at several wavelengths, as well as cloud condensation nuclei (CCN) concentrations at fixed supersaturations and lognormal fits to four modes. Dry extinction and absorption were compared with direct in situ measurements, and AOD derived from the extinction profiles was compared with remotely sensed AOD measurements from the ground-based Aerosol Robotic Network (AERONET); this comparison showed no substantial bias. The purpose of this work is to describe the methodology by which ambient aerosol properties are estimated from the in situ measurements, provide statistical descriptions of the aerosol characteristics of different remote air mass types, examine the contributions to AOD from different aerosol types in different air masses, and provide an entry point to the ATom aerosol database. The contributions of different aerosol types (dust, sea salt, biomass burning, etc.) to AOD generally align with expectations based on location of the profiles relative to continental sources of aerosols, with sea salt and aerosol water dominating the column extinction in most remote environments and dust and biomass burning (BB) particles contributing substantially to AOD, especially downwind of the African continent. Contributions of dust and BB aerosols to AOD were also significant in the free troposphere over the North Pacific. Comparisons of lognormally fitted size distribution parameters to values in the Optical Properties of Aerosols and Clouds (OPAC) database commonly used in global models show significant differences in the mean diameters and standard deviations for accumulation-mode particles and coarse-mode dust. In contrast, comparisons of lognormal parameters derived from the ATom data with previously published shipborne measurements in the remote marine boundary layer show general agreement. The dataset resulting from this work can be used to improve global-scale representation of climate-relevant aerosol properties in remote air masses through comparison with output from global models and assumptions used in retrievals of aerosol properties from both ground-based and satellite remote sensing. Text Aerosol Robotic Network albedo Arctic Atlantic Arctic Atlantic-Arctic Copernicus Publications: E-Journals Arctic Pacific Atmospheric Chemistry and Physics 21 19 15023 15063 |