Evaluation de la pertinence du couplage entre le modèle régional MAR et le modèle de calotte glaciaire GRISLI sur le Groenland

• Main Author: Wyard, Coraline
• Other Authors: Fettweis, Xavier
• Format: Master Thesis
• Language: French
• Published: ULiège - Université de Liège 2014
• Subjects: Greenland ice sheet melting; Coupling; Regional climate model; Ice sheet model; Sea level rise; Global warming; Modèle de calotte glaciaire; Elévation du niveau des mers; Réchauffement climatique; Fonte de la calotte glaciaire du Groenland; Couplage; Modèle climatique régional; Physical; chemical; mathematical & earth Sciences; Earth sciences & physical geography; Physique; chimie; mathématiques & sciences de la terre; Sciences de la terre & géographie physique; Greenland; Groenland; Ice Sheet
• Online Access: https://orbi.uliege.be/handle/2268/172823; https://orbi.uliege.be/bitstream/2268/172823/1/m%c3%a9moire.pdf

During the two last decades, the Greenland ice sheet (GrIs) contribution to the global mean sea level (GMSL) rise has significantly increased. In the future, difficulties remain to assess the GrIs contribution to GMSL rise because of large uncertainties linked to the feedback between the surface mass balance (SMB) and the elevation of the GrIs. In 2013, Xavier Fettweis, my promoter, has coupled a regional climate model (RCM), the model MAR, with an ice sheet model (ISM), the model GRISLI, in order to account of this feedback and, in this way, to improve the assessment of the future GrIs contribution to the GMSL rise. The aim of this study is to assess the pertinence of the MAR−GRISLI coupling which requires long computation time. Nine imulations were carried out with GRISLI. Six of these simulations consisted in forcing GRISLI with several present days MAR outputs (SMB and surface temperature) in order to identify the GRISLI biases. The three last simulations consisted in forcing GRISLI until 2100 with future non-coupled, coupled and modified non- coupled MAR outputs in order to find a technique to avoid the coupling. The results show that initial conditions need to be improved and that the ice flow velocities required recalibration because an abnormal present-day thickening of the GrIs margins. Ice calving only depends on ice sheet extension because of constant ice flow velocities. The MAR−GRISLI coupling can be avoided until the middle of the 2080s. Beyond these years, the SMB correction is too large so that the thinning of the GrIs margins is overestimated. In a further study, the SMB correction could be reduced to avoid the MAR−GRISLI coupling over longer periods. GRISLI could be improved or replaced by a more complex ISM with dynamic ice flow velocities to enhance the results. La contribution à la hausse du NGMM de l'inlandsis du Groenland a fortement augmenté au cours de ces vingt dernières années et sa contribution future est entachée de grandes incertitudes notamment liées à la rétroaction liant le BMS ...