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Satellites reveal Earth's seasonally shifting dust emission sources

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posted on 2023-05-09, 15:50 authored by Adrian Chappell, Nicholas Webb, Mark Hennen, Kirsten Schepanski, Philippe Ciais, Yves Balkanski, Charles Zender, Ina Tegen, Zeng Zhenzhong, Daniel Tong, Barry Baker, Marie Ekstrom, Matthew BaddockMatthew Baddock, Frank Eckardt, Tarek Kandakji, Jeffrey Leff, Mohamad Nobakht, Johanna von Holdt, John Leys

Establishing mineral dust impacts on Earth's systems requires numerical models of the dust cycle. Differences between dust optical depth (DOD) measurements and modelling the cycle of dust emission, atmospheric transport, and deposition of dust indicate large model uncertainty due partially to unrealistic model assumptions about dust emission frequency. Calibrating dust cycle models to DOD measurements typically in North Africa, are routinely used to reduce dust model magnitude. This calibration forces modelled dust emissions to match atmospheric DOD but may hide the correct magnitude and frequency of dust emission events at source, compensating biases in other modelled processes of the dust cycle. Therefore, it is essential to improve physically based dust emission modules.

Here we use a global collation of satellite observations from previous studies of dust emission point source (DPS) dichotomous frequency data. We show that these DPS data have little-to-no relation with MODIS DOD frequency. We calibrate the albedo-based dust emission model using the frequency distribution of those DPS data. The global dust emission uncertainty constrained by DPS data (±3.8 kg m−2 y−1) provides a benchmark for dust emission model development. Our calibrated model results reveal much less global dust emission (29.1 ± 14.9 Tg y−1) than previous estimates, and show seasonally shifting dust emission predominance within and between hemispheres, as opposed to a persistent North African dust emission primacy widely interpreted from DOD measurements.

Earth's largest dust emissions, proceed seasonally from East Asian deserts in boreal spring, to Middle Eastern and North African deserts in boreal summer and then Australian shrublands in boreal autumn-winter. This new analysis of dust emissions, from global sources of varying geochemical properties, have far-reaching implications for current and future dust-climate effects. For more reliable coupled representation of dust-climate projections, our findings suggest the need to re-evaluate dust cycle modelling and benefit from the albedo-based parameterisation.

Funding

US National Science Foundation (EAR-1853853)

Collaborative Research: NSFGEO-NERC: Aeolian dust responses to regional ecosystem change

Natural Environment Research Council

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History

School

  • Social Sciences and Humanities

Department

  • Geography and Environment

Published in

Science of The Total Environment

Volume

883

Publisher

Elsevier

Version

  • VoR (Version of Record)

Rights holder

© The Author(s)

Publisher statement

This is an Open Access Article. It is published by Elsevier under the Creative Commons Attribution 4.0 International Licence (CC BY). Full details of this licence are available at: http://creativecommons.org/licenses/by/4.0/

Acceptance date

2023-04-07

Publication date

2023-04-23

Copyright date

2023

ISSN

0048-9697

eISSN

1879-1026

Language

  • en

Depositor

Dr Matthew Baddock. Deposit date: 28 April 2023

Article number

163452

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