Wiggs, G.F.S., Baddock, M.C., Thomas, D.S.G. et al. (7 more authors) (2022) Quantifying mechanisms of aeolian dust emission : field measurements at Etosha Pan, Namibia. Journal of Geophysical Research: Earth Surface, 127 (8). ISSN 2169-9003
Abstract
Determining the controls on aeolian dust emissions from major sources is necessary for reliable quantification of atmospheric aerosol concentrations and fluxes. However, ground-based measurements of dust emissions at-source are rare and of generally short duration, failing to capture the annual cycle. Here, we provide new insights into dust dynamics by measuring aerosol concentrations and meteorological conditions for a full year (July 2015-June 2016) at Etosha Pan, Namibia, a globally significant dust source. Surface deployed field instrumentation provided 10-minute averaged data on meteorological conditions, aerosol concentration (mg/m3), and horizontal dust flux (g/m2/min10). A Doppler LiDAR provided additional data for some of the period. 51 significant dust events were identified in response to strong E-ENE winds. We demonstrate that these events occurred throughout the year and were not restricted to the austral winter, as previously indicated by satellite observations. Peak horizontal flux occurred in the spring (November) due to strengthening erosive winds and highly desiccating conditions increasing surface erodibility. We identify a strong seasonal differentiation in the meteorological mechanisms controlling dust uplift; low-level jets (LLJ) on dry winter mornings (61% of all events), and cold pool outflows (CPO) in humid summer evenings (39% of events). Significantly, we demonstrate a very strong bias towards the contribution of low frequency and high magnitude events, with nearly 31% of annual horizontal dust flux generated by only 6 individual events. Our study demonstrates how longer-term (≈1 year), ground-based, and at-source field measurements can radically improve interpretations of dust event dynamics and controls at major source locations.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © 2022. The Authors. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited (http://creativecommons.org/licenses/by/4.0/). |
Keywords: | Aeolian Dust Emissions; Mineral Aerosols; Etosha Pan; Low Level Jet; Cold Pool Outflow |
Dates: |
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Institution: | The University of Sheffield |
Academic Units: | The University of Sheffield > Faculty of Social Sciences (Sheffield) > Department of Geography (Sheffield) |
Funding Information: | Funder Grant number Natural Environment Research Council NE/H023410/1 |
Depositing User: | Symplectic Sheffield |
Date Deposited: | 22 Aug 2022 09:19 |
Last Modified: | 26 Sep 2022 08:38 |
Status: | Published |
Publisher: | Wiley (on behalf of the American Geophysical Union) |
Refereed: | Yes |
Identification Number: | 10.1029/2022jf006675 |
Related URLs: | |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:190241 |