Preprints
https://doi.org/10.5194/acp-2021-4
https://doi.org/10.5194/acp-2021-4

  18 Jan 2021

18 Jan 2021

Review status: this preprint is currently under review for the journal ACP.

Contribution of the world's main dust source regions to the global cycle of desert dust

Jasper F. Kok1, Adeyemi A. Adebiyi1, Samuel Albani2,3, Yves Balkanski3, Ramiro Checa-Garcia3, Mian Chin4, Peter R. Colarco4, Douglas S. Hamilton5, Yue Huang1, Akinori Ito6, Martina Klose7, Longlei Li5, Natalie M. Mahowald5, Ron L. Miller8, Vincenzo Obiso7,8, Carlos Pérez García-Pando7,9, Adriana Rocha-Lima10,11, and Jessica S. Wan5 Jasper F. Kok et al.
  • 1Department of Atmospheric and Oceanic Sciences, University of California, Los Angeles, CA 90095, USA
  • 2Department of Environmental and Earth Sciences, University of Milano-Bicocca, Milano, Italy
  • 3Laboratoire des Sciences du Climat et de l’Environnement, CEA-CNRS-UVSQ-UPSaclay, Gif-sur-Yvette, France
  • 4Atmospheric Chemistry and Dynamics Laboratory, NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA
  • 5Department of Earth and Atmospheric Sciences, Cornell University, Ithaca, NY 14850, USA
  • 6Yokohama Institute for Earth Sciences, JAMSTEC, Yokohama, Kanagawa 236-0001, Japan
  • 7Barcelona Supercomputing Center (BSC), 08034 Barcelona, Spain
  • 8NASA Goddard Institute for Space Studies, New York NY10025 USA
  • 9ICREA, Catalan Institution for Research and Advanced Studies, 08010 Barcelona, Spain
  • 10Physics Department, UMBC, Baltimore, Maryland, USA
  • 11Joint Center Joint Center for Earth Systems Technology, UMBC, Baltimore, Maryland, USA

Abstract. Even though desert dust is the most abundant aerosol by mass in Earth's atmosphere, the relative contributions of the world’s major dust source regions to the global dust cycle remain poorly constrained. This problem hinders accounting for the potentially large impact of regional differences in dust properties on clouds, the Earth's energy balance, and terrestrial and marine biogeochemical cycles. Here, we constrain the contribution of each of the world’s main dust source regions to the global dust cycle. We use an analytical framework that integrates an ensemble of global model simulations with observationally informed constraints on the dust size distribution, extinction efficiency, and regional dust aerosol optical depth. We obtain a data set that constrains the relative contribution of each of nine major source regions to size-resolved dust emission, atmospheric loading, optical depth, concentration, and deposition flux. We find that the 22–29 Tg (one standard error range) global loading of dust with geometric diameter up to 20 μm is partitioned as follows: North African source regions contribute ~50 % (11–15 Tg), Asian source regions contribute ~40 % (8–13 Tg), and North American and Southern Hemisphere regions contribute ~10 % (1.8–3.2 Tg). Current models might on average be overestimating the contribution of North African sources to atmospheric dust loading at ~65 %, while underestimating the contribution of Asian dust at ~30 %. However, both our results and current models could be affected by unquantified biases, such as due to errors in separating dust aerosol optical depth from that produced by other aerosol species in remote sensing retrievals in poorly observed desert regions. Our results further show that each source region's dust loading peaks in local spring and summer, which is partially driven by increased dust lifetime in those seasons. We also quantify the dust deposition flux to the Amazon rainforest to be ~10 Tg/year, which is a factor of 2–3 less than inferred from satellite data by previous work that likely overestimated dust deposition by underestimating the dust mass extinction efficiency. The data obtained in this paper can be used to obtain improved constraints on dust impacts on clouds, climate, biogeochemical cycles, and other parts of the Earth system.

Jasper F. Kok et al.

Status: open (until 15 Mar 2021)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse

Jasper F. Kok et al.

Jasper F. Kok et al.

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Short summary
The many impacts of dust on the Earth system depend on dust mineralogy, which varies between dust source regions. We constrain the contribution of the world's main dust source regions by integrating dust observations with global model simulations. We find that Asian dust contributes more, and that North African dust contributes less, than models account for. We obtain a data set of each source region's contribution to the dust cycle that can be used to constrain dust impacts on the Earth system.
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