On the Late Saalian glaciation (160 - 140 ka): a climate modeling study

• Main Author: Colleoni, Florence
• Other Authors: Laboratoire de glaciologie et géophysique de l'environnement (LGGE), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB Université de Savoie Université de Chambéry )-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB Université de Savoie Université de Chambéry )-Centre National de la Recherche Scientifique (CNRS), Université Joseph-Fourier - Grenoble I, Stockholm University, Gerhard Krinner and Martin Jakobsson([e-mail], [e-mail]), ANR IDEGLACE, SUCLIM (Stockholm Univ.), The Bert Bolin Center for Climate Research, Explora Doc, Lavoisier Cotutelle
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: HAL CCSD 2009
• Subjects: atmospheric modeling; ice sheets; surface mass balance; paleoclimate; dust; proglacial lakes; sea surface temperature; Saalian; Quaternary; modélisation atmosphérique; calottes de glace; bilan de masse en surface; paleoclimat; végétation; poussières; lacs proglaciaires; température de surface océanique; Saalien; Quaternaire; [SDU.STU.CL]Sciences of the Universe [physics]/Earth Sciences/Climatology; Arctic; Arctic Ocean; Canada; canada basin; Ice Sheet; Ice Shelf
• Online Access: https://tel.archives-ouvertes.fr/tel-00418445; https://tel.archives-ouvertes.fr/tel-00418445/document; https://tel.archives-ouvertes.fr/tel-00418445/file/these-colleoni.pdf

Rédigé le 8 mai 2009 Accepté pour soutenance le 15 juillet 2009 This thesis focuses on the glaciation of the Late Saalian period (160 -140 ka) over Eurasia. The Quaternary Environment of the Eurasian North project evidenced that during this period, the Eurasian ice sheet was substantially larger than during the entire Weichselian cycle and especially than during the Last Glacial Maximum (21 ka, LGM). The Late Saalian astronomical forcing were different than during the LGM while greenhouse gas concentrations were similar. To understand how this ice sheet could have grown so large over Eurasia during the Late Saalian, we use an Atmospherical General Circulation Model (AGCM), an AGCM coupled to an oceanic mixed layer and a vegetation model to explore the influence of regional parameters, sea surface temperatures (SST) and orbital parameters on the surface mass balance (SMB) of the Late Saalian Eurasian ice sheet. At 140 ka, proglacial lakes, vegetation and simulated Late Saalian SST cool the Eurasian climate, reducing the ablation along the southen margins. Dust deposition on snow have the opposite effect. The presence of a Canada Basin ice-shelf during MIS 6 in the Arctic Ocean, does not affect the mass balance of the ice sheet. According to geological evidences, the Late Saalian Eurasian ice sheet reached its maximum extent before 160 ka. Northern Hemisphere high latitudes summer insolation shows a large insolation peak towards 150 ka. The simulated climate prior to 140 ka is milder and ablation is larger along the southern margins of the Eurasian ice sheet although the mean annual SMB is positive. The Late Saalian Eurasian ice sheet, may have been large enough to generate its own cooling needed for its maintenance over Eurasia. Ce travail se concentre essentiellement sur le glaciation de la fin du Saalien (160 -140 ka) en Eurasie. Les résultats du projet Quaternary Environment of the Eurasian North montrent que durant cette période, la calotte Eurasienne était plus grosse que durant le Dernier Maximum ...