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Journal of Geophysical Research: Atmospheres

Characterization of dust emission from alluvial sources using aircraft observations and high-resolution modeling

Authors

  • K. Schepanski,

    Corresponding author
    1. School of Earth and Environment, University of Leeds, Leeds, UK
    2. Now at Leibniz Institute for Tropospheric Research, Leipzig, Germany
    • Corresponding author: K. Schepanski, Leibniz Institute for Tropospheric Research, Permoser Str. 15, DE-04318 Leipzig, Germany. (schepanski@tropos.de)

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  • C. Flamant,

    1. Laboratoire Atmosphères, Milieux, Observations Spatiales, CNRS-Université Pierre et Marie Curie and Université Versailles Saint Quentin, Paris, France
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  • J.-P. Chaboureau,

    1. Laboratoire d'Aérologie, University of Toulouse and CNRS, Toulouse, France
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  • C. Kocha,

    1. Laboratoire Atmosphères, Milieux, Observations Spatiales, CNRS-Université Pierre et Marie Curie and Université Versailles Saint Quentin, Paris, France
    2. Centre National de Recherches Météorologique, CNRM and GAME, URA 1357, CNRS and Météo France, Toulouse, France
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  • J. R. Banks,

    1. Space and Atmospherics Physics Group, Imperial College London, London, UK
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  • H. E. Brindley,

    1. Space and Atmospherics Physics Group, Imperial College London, London, UK
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  • C. Lavaysse,

    1. Laboratoire Atmosphères, Milieux, Observations Spatiales, CNRS-Université Pierre et Marie Curie and Université Versailles Saint Quentin, Paris, France
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  • F. Marnas,

    1. Laboratoire des Sciences du Climat et de l'Environnement, CEA and CNRS, Gif-sur-Yvette, France
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  • J. Pelon,

    1. Laboratoire Atmosphères, Milieux, Observations Spatiales, CNRS-Université Pierre et Marie Curie and Université Versailles Saint Quentin, Paris, France
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  • P. Tulet

    1. Laboratoire de l'Atmosphère et des Cyclones, UMR 8105, Université de La Réunion, CNRS and Météo-France, Saint-Denis de La Réunion, France
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Abstract

[1] We investigate mineral dust emission from alluvial sediments within the upland region in northern Mauritania in the vicinity of a decaying nocturnal low-level jet (LLJ). For the first time, the impact of valleys that are embedded in a rather homogeneous surrounding is investigated with regard to their role as dust source. Measures for local atmospheric dust burden were retrieved from airborne observations, satellite observations, and model simulations and analyzed in order to provide complementary information at different horizontal scales. Observations by the LEANDRE Nouvelle Generation backscatter lidar system flying aboard the French Falcon 20 aircraft were taken along five parallel flight legs perpendicular to the orientation of the main valley system dominating the topography of the study area. Results from a comparison of lidar-derived extinction coefficients with topography and aerial photographs confirm the relevance of (1) alluvial sediments at the valley bottoms as a dust source, and (2) the break-down of the nocturnal LLJ as a trigger for dust emission in this region. An evaluation of the AROME regional model, forecasting dust at high resolution (5 km grid), points toward an under-representation of alluvial dust sources in this region. This is also evident from simulations by the MesoNH research model. Although MesoNH simulations show higher dust loadings than AROME, which are more comparable to the observations, both models underestimate the dust concentrations within the boundary layer compared to lidar observations. A sensitivity study on the impact of horizontal grid spacing (5 km versus 1 km) highlights the importance of spatial resolution on simulated dust loadings.

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