Quantifying Mechanisms of Aeolian Dust Emission: Field Measurements at Etosha Pan, Namibia

作者：Giles Wiggs, Matthew Baddock, David S.G. Thomas, Richard Washington, Joanna M. Nield, Sebastian Engelstaedter, Robert G. Bryant, Frank D. Eckardt, Johanna von Holdt, Shayne Kötting · 发表于：Journal of Geophysical Research Earth Surface · 年份：2022 · DOI：10.1029/2022jf006675 · 被引用次数：16 · 研究领域：Atmospheric aerosols and clouds、Atmospheric chemistry and aerosols、Aeolian processes and effects

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‐min averaged data on meteorological conditions, aerosol concentration (mg/m 3 ), and horizontal dust flux (g/m 2 /min 10 ). 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 on dry winter mornings (61% of all events), and cold pool outflows in humid summer evenings (39% of events). Significantly, we demonstrate a very strong bias toward the contribution of low frequency and high magnitude even...