Tracer transport in the Greenland Ice Sheet: constraints on ice cores and glacial history |
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| Institution: | 1. Department of Earth and Ocean Sciences, University of British Columbia, 6339 Stores Road, Vancouver, BC, Canada V6T 1Z4;2. Laboratoire de Glaciologie et Géophysique de l’Environnement—Université Joseph Fourier, BP 96, 38402 St-Martin d’Hères Cedex, France;3. Department of Geography, University of Calgary, 2500 University Drive N.W., Calgary, AB, Canada T2N 1N4;1. School of Physics and Microelectronics Science, Hunan University, Changsha, 410082, China;2. College of Materials Science and Engineering, Hunan University, Changsha 410082, China;3. Department of Applied Physics, Chang’an University, Xi’an 710064, China;4. College of Physics and Electronics, Hunan University of Arts and Science, Changde 415000, China;5. Department of Electronic and Communication Engineering, Changsha University, Changsha 410003, China;6. Department of Information Engineering, Gannan Medical University, Ganzhou 341000, China;1. Centre for Glaciology, Department of Geography and Earth Sciences, Aberystwyth University, Aberystwyth, SY23 3DB, UK;2. School of Geography, University of Leeds, Leeds, LS2 9JT, UK;3. Swiss Federal Research Institute WSL, 8903 Birmensdorf, Switzerland;4. Department of Geography, University of Sheffield, Sheffield, S10 2TN, UK;1. Department of Geology, University of Vermont, Burlington, VT, USA;2. Department of Earth and Environmental Sciences, Boston College, Boston, MA, USA;3. Department of Natural and Applied Science, Bentley University, Waltham, MA, USA;4. Department of Earth and Environmental Sciences, Tulane University, New Orleans, LA, USA;5. Department of Physics and Astronomy, Purdue University, West Lafayette, IN, USA;6. Department of Earth, Atmospheric, and Planetary Sciences, Purdue University, West Lafayette, IN, USA;7. Center for Accelerator Mass Spectrometry, Lawrence Livermore National Laboratory, Livermore, CA, USA;1. Institute of Earth Sciences, Heidelberg University, Im Neuenheimer Feld 234-236, D-69120, Heidelberg, Germany;2. Department of Geography, University of Portsmouth, Buckingham Building, Lion Terrace, Portsmouth, PO1 3HE, United Kingdom;3. Department of Geography, School of Environment, Education and Development, University of Manchester, Manchester, M13 9PL, United Kingdom;4. Helmholtz Centre Potsdam, GFZ German Research Centre for Geosciences, Section 4.3, Chemistry and Physics of Earth Materials, Telegrafenberg, D-14773, Potsdam, Germany;5. Institute of Botany, University of Hohenheim, Garbenstraße 30, D-70593, Stuttgart, Germany;6. School of Geography, Geology and the Environment, Keele University, Keele, Staffordshire, ST5 5BG, United Kingdom |
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| Abstract: | The climate history and dynamics of the Greenland Ice Sheet are studied using a coupled model of the depositional provenance and transport of glacier ice, allowing simultaneous prediction of the detailed isotopic stratigraphy of ice cores at all the major Greenland sites. Adopting a novel method for reconstructing the age–depth relationship, we greatly improve the accuracy of semi-Lagrangian tracer tracking schemes and can readily incorporate an age-dependent ice rheology. The larger aim of our study is to impose new constraints on the glacial history of the Greenland Ice Sheet. Leading sources of uncertainty in the climate and dynamic history are encapsulated in a small number of parameters: the temperature and elevation isotopic sensitivities, the glacial–interglacial precipitation contrast and the effective viscosity of ice in the flow law. Comparing predicted and observed ice layering at ice core sites, we establish plausible ranges for the key model parameters, identify climate and dynamic histories that are mutually consistent and recover the past depositional elevation of ice cores to ease interpretation of their climatic records. With the coupled three-dimensional model of ice dynamics and provenance transport we propose a method to place all the ice core records on a common time scale and use discrepancies to adjust the reconstructed climate history. Analysis of simulated GRIP ice layering and borehole temperature profiles confirms that the GRIP record is sensitive to the dynamic as well as to the climatic history, but not enough to strongly limit speculation on the state of the Greenland Ice Sheet during the Eemian. In contrast, our study indicates that the Dye 3 and Camp Century ice cores are extremely sensitive to ice dynamics and greatly constrain Eemian ice sheet reconstructions. We suggest that the maximum Eemian sea-level contribution of the ice sheet was in the range of 3.5–4.5 m. |
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