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Coupled simulations of the mid-Holocene and Last Glacial Maximum: new results from PMIP2
1Laboratoire des Sciences du Climat et de l'Environnement, Unité mixte CEA-CNRS-UVSQ, Orme des Merisiers, bât. 712, 91191 Gif-sur-Yvette Cedex, France
2National Center for Atmospheric Research, 1850 Table Mesa Drive, Boulder, Colorado, USA
3School of Geographical Sciences, University of Bristol, Bristol, BS8 1SS, UK
4Center for climate System Research, The Univ. of Tokyo, Japan 277-8568 and FRCGC/JAMSTEC, Yokohama, 236-0001 Japan
5Met Office Hadley Centre, Fitzroy Road, Exeter EX1 3PB, UK
6Université Catholique de Louvain, Institut d'Astronomie et de Géophysique Georges Lemaître, 1348 Louvain-la-Neuve, Belgium
7Meteorological Research Institute, Tsukuba, Ibaraki 305-0052, Japan
8Univ. Bremen, FB5 Geosciences, Geosystem modelling, P.O. Box 330 440, 28334 Bremen, Germany
9Royal Netherlands Meteorological Institute, PO Box 201, 3730 AE De Bilt, The Netherlands
10LASG, Institute of Atmospheric Physics, Chinese Academy of Sciences, P.O. Box 9804, Beijing 100029, P.R. China
Abstract. A set of coupled ocean-atmosphere simulations using state of the art climate models is now available for the Last Glacial Maximum and the mid-Holocene through the second phase of the Paleoclimate Modeling Intercomparison Project (PMIP2). This study presents the large scale features of the simulated climates and compares the new model results to those of the atmospheric models from the first phase of the PMIP, for which sea surface temperature was prescribed or computed using simple slab ocean formulations. We consider first the large scale features of the climate change, pointing out some of the major differences between the different sets of experiments. Then we quantify the latitudinal shift of the location of the ITCZ in the tropical regions during boreal summer. It is shown that this shift is limited for LGM, whereas a northward shift and an increase of precipitation are well depicted for mid-Holocene in continental regions affected by monsoon precipitation. In the last part we quantify for both periods the feedback from snow and sea-ice in mid and high latitudes. We show that it contributes for half of the cooling in the northern hemisphere for LGM, the second half being achieved by the reduced CO2 and water vapour in the atmosphere. For mid-Holocene the snow and albedo feedbacks strengthen spring cooling and enhance boreal summer warming, whereas water vapour reinforces the late summer warming. These feedbacks are modest in the southern hemisphere. For LGM most of the surface cooling is due to CO2 and water vapour.
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Citation: Braconnot, P., Otto-Bliesner, B., Harrison, S., Joussaume, S., Peterchmitt, J.-Y., Abe-Ouchi, A., Crucifix, M., Fichefet, T., Hewitt, C. D., Kageyama, M., Kitoh, A., Loutre, M.-F., Marti, O., Merkel, U., Ramstein, G., Valdes, P., Weber, L., Yu, Y., and Zhao, Y.: Coupled simulations of the mid-Holocene and Last Glacial Maximum: new results from PMIP2, Clim. Past Discuss., 2, 1293-1346, 2006. Bibtex EndNote Reference Manager
