González-Flórez, Cristina ; Klose, Martina ; Alastuey, Andrés ; Dupont, Sylvain ; Escribano, Jerónimo ; Etyemezian, Vicken ; Gonzalez-Romero, Adolfo ; Huang, Yue ; Kandler, Konrad ; Nikolich, George ; Panta, Agnesh ; Querol, Xavier ; Reche, Cristina ; Yus-Díez, Jesús ; Pérez García-Pando, Carlos (2024)
Insights into the size-resolved dust emission from field measurements in the Moroccan Sahara.
In: Atmospheric Chemistry and Physics, 2023, 23 (12)
doi: 10.26083/tuprints-00024772
Article, Secondary publication, Publisher's Version
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Item Type: | Article | ||||
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Type of entry: | Secondary publication | ||||
Title: | Insights into the size-resolved dust emission from field measurements in the Moroccan Sahara | ||||
Language: | English | ||||
Date: | 16 January 2024 | ||||
Place of Publication: | Darmstadt | ||||
Year of primary publication: | 2023 | ||||
Place of primary publication: | Göttingen | ||||
Publisher: | Copernicus Publications | ||||
Journal or Publication Title: | Atmospheric Chemistry and Physics | ||||
Volume of the journal: | 23 | ||||
Issue Number: | 12 | ||||
DOI: | 10.26083/tuprints-00024772 | ||||
Corresponding Links: | |||||
Origin: | Secondary publication DeepGreen | ||||
Abstract: | The particle size distribution (PSD) of mineral dust has a strong effect on the impacts of dust on climate. However, our understanding of the emitted dust PSD, including its variability and the fraction of super-coarse dust (diameter >10 µm), remains limited. Here, we provide new insights into the size-resolved dust emission process based on a field campaign performed in the Moroccan Sahara in September 2019 in the context of the FRontiers in dust minerAloGical coMposition and its Effects upoN climaTe (FRAGMENT) project. The obtained dust concentration and diffusive flux PSDs show significant dependencies upon the friction velocity (u*), wind direction and type of event (regular events versus haboob events). For instance, the number fraction of sub-micrometre particles increases with u*, along with a large decrease in the mass fraction of super-coarse dust. We identify dry deposition, which is modulated by u* and fetch length, as a potential cause for this PSD variability. Using a resistance model constrained with field observations to estimate the dry deposition flux and thereby also the emitted dust flux, we show that deposition could represent up to ∼90% of the emission of super-coarse particles (>10 µm) and up to ∼65% of the emission of particles as small as ∼5 µm in diameter. Importantly, removing the deposition component significantly reduces the variability with u* in the PSD of the emitted dust flux compared with the diffusive flux, particularly for super-coarse dust. The differences between regular and haboob event concentration and diffusive flux PSDs are suspected to result from a smaller and variable dust source fetch during the haboob events, and/or an increased resistance of soil aggregates to fragmentation associated with the observed increase in relative humidity along the haboob outflow. Finally, compared to the invariant emitted dust flux PSD estimated based on brittle fragmentation theory, we obtain a substantially higher proportion of super-micrometre particles in the dust flux. Overall, our results suggest that dry deposition needs to be adequately considered to estimate the emitted PSD, even in studies limited to the fine and coarse size ranges (<10 µm). |
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Status: | Publisher's Version | ||||
URN: | urn:nbn:de:tuda-tuprints-247721 | ||||
Additional Information: | Special Issue: Dust aerosol measurements, modeling and multidisciplinary effects (AMT/ACP inter-journal SI) |
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Classification DDC: | 500 Science and mathematics > 550 Earth sciences and geology 600 Technology, medicine, applied sciences > 624 Civil engineering and environmental protection engineering |
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Divisions: | 11 Department of Materials and Earth Sciences > Earth Science > Atmospheric Aerosol | ||||
Date Deposited: | 16 Jan 2024 13:04 | ||||
Last Modified: | 18 Jan 2024 10:12 | ||||
SWORD Depositor: | Deep Green | ||||
URI: | https://tuprints.ulb.tu-darmstadt.de/id/eprint/24772 | ||||
PPN: | 514762055 | ||||
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