Etude des propriétés physiques des aérosols de la moyenne et haute atmosphère à partir d'une nouvelle analyse des observations du GOMOS-ENVISAT pour la période 2002-2006

Abstract : The study of stratospheric aerosols is crucial for modeling precisely the earth´s radiative budget and because of their influence on ozone depletion. Since the discovery of Junge layer, this area of research has been through various situations: from the greatest volcanic upload of last century after Mount Pinatubo eruption in 1991, and slowly recovering to background levels reached in the 2000s, which allow the study of other than volcanic particles. However, the vertical and spatial distribution of these aerosols in the middle and high stratosphere is still poorly documented and not yet totally understood. Their detection presents many difficulties: the particles have a great variety of origins, compositions, shapes and sizes, and their low optical thicknesses make accurate results necessary. An inversion algorithm developed in the LPC2E has been adapted to the analysis of level 1b data from GOMOS instrument onboard ENVISAT. The star occultation technique leads to a good (but irregular) spatial and temporal sampling, and a data selection criteria allows the analysis of accurate results, which validation is led for the study of aerosol extinction. A global climatology is then established for the August 2002 to July 2006 period, and shows the permanent presence of aerosol particles around the globe, up to 45 km altitude. The temporal variability shows a progressive enhancement of the mean content from 2002 in the tropics, and was useful to study the influence of the quasi-biennial oscillation in the middle stratosphere, as well as some seasonal features. The study of the spectral dependence informs about the size and nature of the particles, mainly sulfate aerosols, but also soot coming from the troposphere and aerosols of extra-terrestrial origin.
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Veronica Salazar. Etude des propriétés physiques des aérosols de la moyenne et haute atmosphère à partir d'une nouvelle analyse des observations du GOMOS-ENVISAT pour la période 2002-2006. Sciences de la Terre. Université d'Orléans, 2010. Français. ⟨NNT : 2010ORLE2062⟩. ⟨tel-00608052⟩

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