CaltechAUTHORS
Published May 14, 2021 | Version Published
Journal Article Open

Chemical transport models often underestimate inorganic aerosol acidity in remote regions of the atmosphere

Creators

  • 1. ROR icon University of Colorado Boulder
  • 2. ROR icon Cooperative Institute for Research in Environmental Sciences
  • 3. ROR icon Aerodyne Research
  • 4. ROR icon National Center for Atmospheric Research
  • 5. ROR icon Colorado Department of Public Health and Environment
  • 6. ROR icon California Institute of Technology
  • 7. ROR icon University of California, Riverside
  • 8. ROR icon University of Maryland, Baltimore County
  • 9. ROR icon Goddard Space Flight Center
  • 10. ROR icon University of California, Irvine
  • 11. ROR icon University of East Anglia
  • 12. TOFWERK USA, Boulder, CO, USA
  • 13. ROR icon Johns Hopkins University
  • 14. ROR icon University of New Hampshire
  • 15. ROR icon Langley Research Center
  • 16. State Key Laboratory at Organic Geochemistry, Guangzhou, Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, China
  • 17. ROR icon Colorado State University
  • 18. ROR icon University of Vienna
  • 19. ROR icon Tofwerk (Switzerland)
  • 20. ROR icon University of Leicester
  • 21. ROR icon University College London
  • 22. ROR icon University of Washington
  • 23. ROR icon Geophysical Fluid Dynamics Laboratory
  • 24. ROR icon Columbia University
  • 25. ROR icon Goddard Institute for Space Studies

Abstract

The inorganic fraction of fine particles affects numerous physicochemical processes in the atmosphere. However, there is large uncertainty in its burden and composition due to limited global measurements. Here, we present observations from eleven different aircraft campaigns from around the globe and investigate how aerosol pH and ammonium balance change from polluted to remote regions, such as over the oceans. Both parameters show increasing acidity with remoteness, at all altitudes, with pH decreasing from about 3 to about −1 and ammonium balance decreasing from almost 1 to nearly 0. We compare these observations against nine widely used chemical transport models and find that the simulations show more scatter (generally R2 < 0.50) and typically predict less acidic aerosol in the most remote regions. These differences in observations and predictions are likely to result in underestimating the model-predicted direct radiative cooling effect for sulfate, nitrate, and ammonium aerosol by 15–39%.

Copyright and License

© The Author(s) 2021. This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/.

Acknowledgement

This work was supported by NASA grants NNX15AH33A, NNX15AJ23G, 80NSSC19K0124, 80NSSC18K0630, NNX15AG61A, NSF grants 1360745, 1652688, and DOE (BER/ASRprogram) DE-SC0016559. We would like to acknowledge high-performance computing support from Cheyenne (doi:10.5065/D6RX99HX) provided by NCAR’s Computational and Information Systems Laboratory, sponsored by the National Sciences Foundation. We thank Charles Brock, Edward Dunlea, Karl Froyd, Daniel Murphy, and Joshua Schwarz for the use of their measurements.

Data Availability

Aircraft observations and chemical transport model output can be found at https://doi.org/10.3334/ORNLDAAC/1857. The data used to estimate condensational sink and volume contribution between non-volatile and all aerosol can be found at https://doi.org/10.3334/ORNLDAAC/1671.

Supplemental Material

Supplementary Information

Supplementary Data 1

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Additional details

Related works

Describes
Journal Article: https://rdcu.be/eLm9S (ReadCube)
Is supplemented by
Software: 10.3334/ORNLDAAC/1857 (DOI)
Dataset: 10.3334/ORNLDAAC/1671 (DOI)

Funding

National Aeronautics and Space Administration
NNX15AH33A
National Aeronautics and Space Administration
NNX15AJ23G
National Aeronautics and Space Administration
80NSSC19K0124
National Aeronautics and Space Administration
80NSSC18K0630
National Aeronautics and Space Administration
NNX15AG61A
National Science Foundation
AGS-1360745
National Science Foundation
AGS-1652688
United States Department of Energy
DE-SC0016559

Dates

Accepted
2021-04-06

Caltech Custom Metadata

Caltech groups
Division of Chemistry and Chemical Engineering (CCE), Division of Engineering and Applied Science (EAS), Division of Geological and Planetary Sciences (GPS)
Publication Status
Published