Three-dimensional distribution of a major Saharan dust outbreak in June 2011 derived from IASI satellite observations

Abstract : The Sahara is the world’s largest source of mineral dust in the atmosphere, which is a key player of the Earth system. At the regional scale, the environmental impacts of desert dust strongly depend on the three-dimensional (3D) distribution of dust plumes resulting from long-range transport. Dust layers can impact chemical balances, atmospheric stability or cloud properties depending on the altitude at which they are transported. Near the surface, dust can directly affect air quality and settle down on the surface by dry deposition. The quantification of such impacts are highly uncertain, particularly due to the sporadic character of dust emissions as well as the large variability of dust properties and occurrence linked to the meteorological controls. A better understanding of the 3D distribution of Saharan dust and the associated mechanisms for uplifting and redistributing it in the vertical is fundamental for quantifying its environmental impacts. This research work presents the first observation of the 3D distribution of a major Saharan dust outbreak over the Sahara in June 2011, using new aerosol retrievals derived from IASI (Infrared Atmospheric Sounding Interferometer). For this, we use a novel auto-adaptive Tikhonov-Philips-type approach called AEROIASI to retrieve vertical profiles of dust extinction coefficient at 10 μm for most cloud-free IASI pixels, both over land (including bright desert surfaces) and ocean. The dust vertical distribution derived from AEROIASI is shown to agree remarkably well with along track transects of CALIOP space-borne lidar vertical profiles as well as with aerosol optical depth derived from AERONET sun photometer measurements over West Africa. A comparison is as well made with airborne lidar and in situ measurements over the Sahara performed in the framework of the FENNEC field campaign. We also compare AEROIASI with several satellite retrievals available over the Sahara (e.g. MODIS-DeepBlue, OMI, SEVIRI). Using AEROIASI observations, we analyse the 3D pathways of the Saharan dust plumes as they are transported across the Sahara. Particularly, we focus our study on the role of cold pools generated by mesoscale convective system, convective mixing in the Saharan atmospheric boundary layer and strong Harmattan winds as mechanisms for vertically redistributing the Saharan dust plumes.
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https://hal-insu.archives-ouvertes.fr/insu-01306503
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Submitted on : Sunday, April 24, 2016 - 5:39:31 PM
Last modification on : Tuesday, November 19, 2019 - 1:52:18 AM

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  • HAL Id : insu-01306503, version 1

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Juan Cuesta, Cyrille Flamant, Maxim Eremenko, Gaëlle Dufour, Benoît Laurent, et al.. Three-dimensional distribution of a major Saharan dust outbreak in June 2011 derived from IASI satellite observations. 4th IASI International Conference, Apr 2016, Antibes Juan-Les-Pins, France. ⟨insu-01306503⟩

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