Ocean / Ice sheet interactions : toward a coupled model system

• Main Author: Merino, Nacho
• Other Authors: Institut des Géosciences de l’Environnement (IGE), Institut de Recherche pour le Développement (IRD)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes 2016-2019 (UGA 2016-2019 ), Université Grenoble Alpes, Gaël Durand, Julien Le Sommer
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: HAL CCSD 2016
• Subjects: Ice sheet; Ocean; Model; Icebergs; Calotte polaire; Océan; Modèle; [SDU.STU.GL]Sciences of the Universe [physics]/Earth Sciences/Glaciology; [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography; Antarctic; Southern Ocean; The Antarctic; Antarc*; Ice Sheet; Ice Shelf; Ice Shelves; Iceberg*; Sea ice
• Online Access: https://theses.hal.science/tel-01760438; https://theses.hal.science/tel-01760438/document; https://theses.hal.science/tel-01760438/file/MERINO_2016_archivage.pdf

The next generation of climate models will include an ice-sheet model in order to improve the ice sheet mass balance projections by accounting for the ice dynamics and ice-oceans interactions. On the one hand, the Southern Ocean (SO) is indeed driving the acceleration of the Antarctic outlet glaciers via an increase in the basal melting of the ice shelves. On the other hand, the increasing ice discharge from Antarctic Ice Sheet (AIS) contributes to the current sea level rise and is likely to become the largest cryospheric contributor to sea level rise by the end of the current century. In addition, the related freshening may have significant implications on future sea-ice cover and on bottom water formation. However, it is not clear yet how the ocean and ice-sheet components of future coupled systems will account for the ice-ocean interactions, which are both causes and consequences of the AIS mass imbalance. Here in this work, different aspects of the standalone ocean and ice-sheet components have been investigated. A first step of this thesis has been focused in the representation of the glacial freshwater fluxes in current ocean models. Based on recent glaciological estimates, the ice shelf basal melting fluxes have been spatially distributed in an ORCA025 grid, and the calving rates have been applied into an improved version of the NEMO-ICB iceberg model. This preliminary study has been used to produce a monthly iceberg meltwater climatology, to be used to force current ocean models. This work shows the importance of representing the iceberg meltwater fluxes when modeling sea ice, which can be inexpensively achieve by using our climatology. The improvements in the representation of the glacial freshwater fluxes have been considered in the study of the ocean model response to the Antarctic mass imbalance. This study considers a realistic perturbation in the glacial freshwater forcing as close as possible as it will be represented in future ice-sheet/ocean models. According to our results, up to 50% of the ...