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Soufre Atmosphérique et Changements Climatiques : une étude de modélisation pour les moyennes et hautes latitudes Sud

Abstract : The mid and high-southern latitudes are still marginally affected by anthropogenic sulfur emissions and the natural cycle of the atmospheric sulfur may still be observed. Sulfur aerosols are well-known for their radiative impact, and thus interact with climate. Antarctic ice cores provide information on the evolution of climate and sulfur deposition at the surface of the ice sheet at glacial-interglacial time scales. The aim of this thesis is to develop and use modeling towards a better understanding of the atmospheric sulfur cycle in antarctic and sub-antarctic regions. An Atmospheric General Circulation Model (AGCM) coupled to a sulfur chemistry module is used: the LMD-ZT-Sulfur model, version 4. The model was first performed (update of both the physical and chemical parts of the model). Further, boundary conditions are adapted to simulate the atmospheric circulation and sulfur cycle at the Last Glacial Maximum, approximately 20,000 years ago. In the model, sulfur is found to be highly sensitive to antarctic sea-ice coverage, which is still poorly known during the ice age. An original dataset of ice-age sea-ice coverage was developed and its impact on the oceanic emissions of dimethyl sulfide, main precursor of sulfur aerosols at high-southern latitudes, is discussed. The model broadly reproduces the glacial deposits of sulfur aerosols on the Antarctic plateau, suggesting little impact of climate on oceanic sulfur production in the Antarctic region. Sensitivity tests were carried out to draw an up-to-date status of major uncertainties and difficulties facing future progress in understanding atmospheric sulfur and climate.
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https://tel.archives-ouvertes.fr/tel-00187947
Contributor : Hélène Castebrunet <>
Submitted on : Thursday, November 15, 2007 - 3:09:24 PM
Last modification on : Thursday, November 19, 2020 - 3:54:26 PM
Long-term archiving on: : Monday, April 12, 2010 - 2:19:59 AM

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  • HAL Id : tel-00187947, version 1

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Hélène Castebrunet. Soufre Atmosphérique et Changements Climatiques : une étude de modélisation pour les moyennes et hautes latitudes Sud. Océan, Atmosphère. Université Joseph-Fourier - Grenoble I, 2007. Français. ⟨tel-00187947⟩

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