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Title: Microphysical explanation of the RH-dependent water affinity of biogenic organic aerosol and its importance for climate

Abstract

A large fraction of atmospheric organic aerosol (OA) originates from natural emissions that are oxidized in the atmosphere to form secondary organic aerosol (SOA). Isoprene (IP) and monoterpenes (MT) are the most important precursors of SOA originating from forests. The climate impacts from OA are currently estimated through parameterizations of water uptake that drastically simplify the complexity of OA. We combine laboratory experiments, thermodynamic modeling, field observations, and climate modeling to (1) explain the molecular mechanisms behind RH-dependent SOA water-uptake with solubility and phase separation; (2) show that laboratory data on IP- and MT-SOA hygroscopicity are representative of ambient data with corresponding OA source profiles; and (3) demonstrate the sensitivity of the modeled aerosol climate effect to assumed OA water affinity. We conclude that the commonly used single-parameter hygroscopicity framework can introduce significant error when quantifying the climate effects of organic aerosol. The results highlight the need for better constraints on the overall global OA mass loadings and its molecular composition, including currently underexplored anthropogenic and marine OA sources.

Authors:
 [1]; ORCiD logo [2]; ORCiD logo [1]; ORCiD logo [3];  [4];  [1];  [5]; ORCiD logo [6]; ORCiD logo [7];  [8];  [9];  [10]; ORCiD logo [11];  [12]; ORCiD logo [13];  [14]; ORCiD logo [15];  [16];  [17]; ORCiD logo [18] more »; ORCiD logo [19];  [16]; ORCiD logo [7]; ORCiD logo [8]; ORCiD logo [20];  [21]; ORCiD logo [3]; ORCiD logo [2]; ORCiD logo [1] « less
  1. Stockholm Univ. (Sweden). Department of Environmental Science and Analytical Chemistry (ACES) and Bolin Centre for Climate research
  2. University of Eastern Finland, Kuopio (Finland). Department of Applied Physics
  3. McGill Univ., Montreal, QC (Canada). Department of Atmospheric and Oceanic Sciences
  4. Chonbuk National University, Jeonju (Korea). Department of Earth and Environmental Sciences; Univ. of British Columbia, Vancouver, BC (Canada). Department of Chemistry
  5. Norwegian Meteorological Institute, Oslo (Norway)
  6. University of Eastern Finland, Kuopio (Finland). Department of Applied Physics; Rice Univ., Houston, TX (United States). Department of Civil and Environmental Engineering
  7. Univ. of Colorado, Boulder, CO (United States). Cooperative Institute for Research in Environmental Sciences and Department of Chemistry and Biochemistry
  8. Texas A & M Univ., College Station, TX (United States). Department of Atmospheric Sciences
  9. Aerodyne Research Inc., Billerica, MA (United States); Boston College, Chestnut Hill, MA (United States). Department of Chemistry
  10. Georgia Inst. of Technology, Atlanta, GA (United States). School of Chemical and Biomolecular Engineering
  11. Georgia Inst. of Technology, Atlanta, GA (United States). School of Earth and Atmospheric Sciences ; Institute for Environmental Research and Sustainable Development, National Observatory of Athens, Palea Penteli (Greece)
  12. Harvard Univ., Cambridge, MA (United States). School of Engineering and Applied Sciences
  13. Department of Environmental Science and Analytical Chemistry (ACES) and Bolin Centre for Climate research, Stockholm University, Stockholm Sweden
  14. Univ. of Helsinki (Finland). Department of Physics
  15. Univ. of Manchester (United Kingdom). School of Earth and Environmental Sciences
  16. Boston College, Chestnut Hill, MA (United States). Department of Chemistry
  17. Aerodyne Research Inc., Billerica, MA (United States)
  18. Stockholm Univ. (Sweden). Department of Meteorology
  19. Georgia Inst. of Technology, Atlanta, GA (United States). School of Chemical and Biomolecular Engineering and School of Earth and Atmospheric Sciences; Institute for Environmental Research and Sustainable Development, National Observatory of Athens, Palea Penteli (Greece); Institute of Chemical Engineering Sciences, Foundation for Research and Technology-Hellas, Patras (Greece)
  20. Univ. of Manchester (United Kingdom). School of Earth and Environmental Sciences and National Centre for Atmospheric Science (NCAS)
  21. Univ. of British Columbia, Vancouver, BC (Canada). Department of Chemistry
Publication Date:
Research Org.:
Univ. of Colorado, Boulder, CO (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23)
OSTI Identifier:
1358118
Alternate Identifier(s):
OSTI ID: 1377937; OSTI ID: 1429324
Grant/Contract Number:
SC0016559; SC0012792
Resource Type:
Journal Article: Published Article
Journal Name:
Geophysical Research Letters
Additional Journal Information:
Journal Volume: 44; Journal Issue: 10; Journal ID: ISSN 0094-8276
Publisher:
American Geophysical Union
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; atmospheric aerosol; secondary organic aerosol; hygroscopicity; aerosol-water interactions; aerosol-climate interactions

Citation Formats

Rastak, N., Pajunoja, A., Acosta Navarro, J. C., Ma, J., Song, M., Partridge, D. G., Kirkevag, A., Leong, Y., Hu, W. W., Taylor, N. F., Lambe, A., Cerully, K., Bougiatioti, A., Liu, P., Krejci, R., Petaja, T., Percival, C., Davidovits, P., Worsnop, D. R., Ekman, A. M. L., Nenes, A., Martin, S., Jimenez, J. L., Collins, D. R., Topping, D. O., Bertram, A. K., Zuend, A., Virtanen, A., and Riipinen, I. Microphysical explanation of the RH-dependent water affinity of biogenic organic aerosol and its importance for climate. United States: N. p., 2017. Web. doi:10.1002/2017GL073056.
Rastak, N., Pajunoja, A., Acosta Navarro, J. C., Ma, J., Song, M., Partridge, D. G., Kirkevag, A., Leong, Y., Hu, W. W., Taylor, N. F., Lambe, A., Cerully, K., Bougiatioti, A., Liu, P., Krejci, R., Petaja, T., Percival, C., Davidovits, P., Worsnop, D. R., Ekman, A. M. L., Nenes, A., Martin, S., Jimenez, J. L., Collins, D. R., Topping, D. O., Bertram, A. K., Zuend, A., Virtanen, A., & Riipinen, I. Microphysical explanation of the RH-dependent water affinity of biogenic organic aerosol and its importance for climate. United States. doi:10.1002/2017GL073056.
Rastak, N., Pajunoja, A., Acosta Navarro, J. C., Ma, J., Song, M., Partridge, D. G., Kirkevag, A., Leong, Y., Hu, W. W., Taylor, N. F., Lambe, A., Cerully, K., Bougiatioti, A., Liu, P., Krejci, R., Petaja, T., Percival, C., Davidovits, P., Worsnop, D. R., Ekman, A. M. L., Nenes, A., Martin, S., Jimenez, J. L., Collins, D. R., Topping, D. O., Bertram, A. K., Zuend, A., Virtanen, A., and Riipinen, I. Fri . "Microphysical explanation of the RH-dependent water affinity of biogenic organic aerosol and its importance for climate". United States. doi:10.1002/2017GL073056.
@article{osti_1358118,
title = {Microphysical explanation of the RH-dependent water affinity of biogenic organic aerosol and its importance for climate},
author = {Rastak, N. and Pajunoja, A. and Acosta Navarro, J. C. and Ma, J. and Song, M. and Partridge, D. G. and Kirkevag, A. and Leong, Y. and Hu, W. W. and Taylor, N. F. and Lambe, A. and Cerully, K. and Bougiatioti, A. and Liu, P. and Krejci, R. and Petaja, T. and Percival, C. and Davidovits, P. and Worsnop, D. R. and Ekman, A. M. L. and Nenes, A. and Martin, S. and Jimenez, J. L. and Collins, D. R. and Topping, D. O. and Bertram, A. K. and Zuend, A. and Virtanen, A. and Riipinen, I.},
abstractNote = {A large fraction of atmospheric organic aerosol (OA) originates from natural emissions that are oxidized in the atmosphere to form secondary organic aerosol (SOA). Isoprene (IP) and monoterpenes (MT) are the most important precursors of SOA originating from forests. The climate impacts from OA are currently estimated through parameterizations of water uptake that drastically simplify the complexity of OA. We combine laboratory experiments, thermodynamic modeling, field observations, and climate modeling to (1) explain the molecular mechanisms behind RH-dependent SOA water-uptake with solubility and phase separation; (2) show that laboratory data on IP- and MT-SOA hygroscopicity are representative of ambient data with corresponding OA source profiles; and (3) demonstrate the sensitivity of the modeled aerosol climate effect to assumed OA water affinity. We conclude that the commonly used single-parameter hygroscopicity framework can introduce significant error when quantifying the climate effects of organic aerosol. The results highlight the need for better constraints on the overall global OA mass loadings and its molecular composition, including currently underexplored anthropogenic and marine OA sources.},
doi = {10.1002/2017GL073056},
journal = {Geophysical Research Letters},
number = 10,
volume = 44,
place = {United States},
year = {Fri Apr 28 00:00:00 EDT 2017},
month = {Fri Apr 28 00:00:00 EDT 2017}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record at 10.1002/2017GL073056

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Cited by: 4works
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  • Cited by 4
  • A large fraction of atmospheric organic aerosol (OA) originates from natural emissions that are oxidized in the atmosphere to form secondary organic aerosol (SOA). Isoprene (IP) and monoterpenes (MT) are the most important precursors of SOA originating from forests. The climate impacts from OA are currently estimated through parameterizations of water uptake that drastically simplify the complexity of OA. We combine laboratory experiments, thermodynamic modeling, field observations, and climate modeling to (1) explain the molecular mechanisms behind RH-dependent SOA water-uptake with solubility and phase separation; (2) show that laboratory data on IP- and MT-SOA hygroscopicity are representative of ambient datamore » with corresponding OA source profiles; and (3) demonstrate the sensitivity of the modeled aerosol climate effect to assumed OA water affinity. We conclude that the commonly used single-parameter hygroscopicity framework can introduce significant error when quantifying the climate effects of organic aerosol. The results highlight the need for better constraints on the overall global OA mass loadings and its molecular composition, including currently underexplored anthropogenic and marine OA sources.« less
  • Recently, attention has been drawn towards black carbon aerosols as a likely short-term climate warming mitigation candidate. However the global and regional impacts of the direct, cloud-indirect and semi-direct forcing effects are highly uncertain, due to the complex nature of aerosol evolution and its climate interactions. Black carbon is directly released as particle into the atmosphere, but then interacts with other gases and particles through condensation and coagulation processes leading to further aerosol growth, aging and internal mixing. A detailed aerosol microphysical scheme, MATRIX, embedded within the global GISS modelE includes the above processes that determine the lifecycle and climatemore » impact of aerosols. This study presents a quantitative assessment of the impact of microphysical processes involving black carbon, such as emission size distributions and optical properties on aerosol cloud activation and radiative forcing. Our best estimate for net direct and indirect aerosol radiative forcing change is -0.56 W/m{sup 2} between 1750 and 2000. However, the direct and indirect aerosol effects are very sensitive to the black and organic carbon size distribution and consequential mixing state. The net radiative forcing change can vary between -0.32 to -0.75 W/m{sup 2} depending on these carbonaceous particle properties. Assuming that sulfates, nitrates and secondary organics form a coating shell around a black carbon core, rather than forming a uniformly mixed particles, changes the overall net radiative forcing from a negative to a positive number. Black carbon mitigation scenarios showed generally a benefit when mainly black carbon sources such as diesel emissions are reduced, reducing organic and black carbon sources such as bio-fuels, does not lead to reduced warming.« less
  • The hygroscopic nature of atmospheric aerosol has generally been associated with its inorganic fraction. In this study, a group contribution method is used to predict the water absorption of secondary organic aerosol (SOA). Compared against growth measurements of mixed inorganic-organic particles, this method appears to provide a first-order approximation in predicting SOA water absorption. The growth of common SOA species is predicted to be significantly less than common atmospheric inorganic salts such as (NH{sub 4}){sub 2}SO{sub 4} and NaCl. Using this group contribution method as a tool in predicting SOA water absorption, an integrated modeling approach is developed combining availablemore » SOA and inorganic aerosol models to predict overall aerosol behavior. The effect of SOA on water absorption and nitrate partitioning between the gas and aerosol phases is determined. On average, it appears that SOA accounts for approximately 7% of total aerosol water and increases aerosol nitrate concentrations by approximately 10%. At high relative humidity and low SOA mass fractions, the role of SOA in nitrate partitioning and its contribution to total aerosol water is negligible. However, the water absorption of SOA appears to be less sensitive to changes in relative humidity than that of inorganic species, and thus at low relative humidity and high SOA mass fraction concentrations, SOA is predicted to account for approximately 20% of total aerosol water and a 50% increase in aerosol nitrate concentrations. These findings could improve the results of modeling studies where aerosol nitrate has often been underpredicted.« less
  • The meso-scale chemistry-transport model CHIMERE is used to assess our understanding of major sources and formation processes leading to a fairly large amount of organic aerosols [OA, including primary OA (POA) and secondary OA (SOA)] observed in Mexico City during the MILAGRO field project (March 2006). Chemical analyses of submicron aerosols from aerosol mass spectrometers (AMS) indicate that organic particles found in the Mexico City basin have a large fraction of oxygenated organic species (OOA), which have strong correspondence with SOA, and that their production actively continues downwind of the city. The SOA formation is modeled here by the first-generationmore » oxidation of anthropogenic (i.e., aromatics, alkanes) and biogenic (i.e., monoterpenes and isoprene) precursors and their partitioning into both organic and aqueous phases. The near-surface model evaluation shows that predicted OA correlates reasonably well with measurements during the campaign, however it remains a factor of 2 lower than the measured total OA. Fairly good agreement is found between predicted and observed POA within the city suggesting that anthropogenic and biomass burning emissions are reasonably captured. Consistent with previous studies in Mexico City, large discrepancies are encountered for SOA species, with a factor of 5-10 model underestimate. When only anthropogenic SOA precursors were considered, the model was able to reproduce within a factor of two the sharp increase in SOA concentrations during the late morning at both urban and near-urban locations. However, predicted SOA concentrations were unrealistically low when photochemistry was not active, especially overnight. These nighttime discrepancies were not significantly reduced when greatly enhanced partitioning to the aerosol phase was assumed. Model sensitivity results suggest that observed nighttime SOA concentrations are strongly influenced by the regional background (~2µg/m3) from biogenic origin, which is transported from the coastal regions into the Mexico City basin. The relative contribution of biogenic SOA to monthly mean SOA levels is estimated to be more than 30% within the city and up to 65-90% at the regional scale (even in the immediate vicinity of the city), which is consistent with measurements of modern carbon during low biomass burning periods. The anthropogenic emissions of isoprene and its nighttime oxidation by NO3 were also found to enhance the SOA mean concentrations within the city by an additional 15%. Our results confirm the large underestimation of the SOA production by traditional models in polluted regions (estimated to 10-20 Tons within the Mexico City metropolitan area during the daytime), and emphasize for the first time the role of biogenic precursors in this region, indicating that they cannot be neglected in modeling studies.« less