An Amundsen Sea source of decadal temperature changes on the Antarctic continental shelf

• Published in: Ocean Dynamics
• Main Authors: Drijfhout, Sybren, S, Bull, Christopher, y S, Hewitt, Helene, Holland, Paul, R, Jenkins, Adrian, Mathiot, Pierre, Garabato, Alberto, Naveira
• Other Authors: School of Ocean and Earth Science UK, University of Southampton, Royal Netherlands Meteorological Institute (KNMI), Universiteit Utrecht / Utrecht University Utrecht, Northumbria University Newcastle, United Kingdom Met Office Exeter, British Antarctic Survey (BAS), Natural Environment Research Council (NERC), Institut des Géosciences de l’Environnement (IGE), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP ), Université Grenoble Alpes (UGA)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2023
• Subjects: Amundsen Sea; Circumpolar Deep Water; Antarctic continental shelf; Subsurface warming; Global ocean model; Basal melt; [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography; [SDE.MCG]Environmental Sciences/Global Changes; [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces; environment; Antarctic; Ross Sea; The Antarctic; Antarc*; Ice Sheet; Ice Shelves
• Online Access: https://hal.science/hal-04693979; https://hal.science/hal-04693979/document; https://hal.science/hal-04693979/file/s10236-023-01587-3.pdf; https://doi.org/10.1007/s10236-023-01587-3

International audience Mass loss from the Antarctic Ice Sheet is dominated by basal melting-induced warm ocean water. Ice-sheet mass loss and thinning of buttressing ice shelves occur primarily in the Amundsen and Bellingshausen Seas. Here, we show that in a global ocean simulation using the 0.25° Nucleus for European Modeling of Ocean (NEMO) model driven by the JRA55 reanalysis from 1982 to 2017, the Amundsen sector of the Antarctic continental shelf acts as a gateway, regulating the on-shelf access of warm Circumpolar Deep Water (CDW) from the deep ocean and its westward transfer to other sectors up to ca. 90° E, particularly the Ross Sea. As a result, anomalies in Antarctic-shelf-averaged temperature mainly originate in the Amundsen sector. These changes are primarily governed by shifts in the Amundsen Sea Low associated with tropical climate variability, modulating the on-shelf transport of CDW via wind-driven perturbations to ocean currents. The ensuing temperature anomalies progress westward from the Amundsen Sea via three distinct routes: a slow, convoluted westward pathway on the shelf via the Antarctic Coastal Current; a faster westward pathway along the shelf break via the Antarctic Slope Current and then onto the shelf along topographic troughs; and a third, eastward route toward the Bellingshausen sector, whereby temperature anomalies are transported into a region of local wind-generated changes farther north. These results emphasize the importance of the Amundsen sector for climate variability over the Antarctic shelves.