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Published November 22, 2019 | Published + Supplemental Material
Journal Article Open

Pathways of ocean heat towards Pine Island and Thwaites grounding lines


In the Amundsen Sea, modified Circumpolar Deep Water (mCDW) intrudes into ice shelf cavities, causing high ice shelf melting near the ice sheet grounding lines, accelerating ice flow, and controlling the pace of future Antarctic contributions to global sea level. The pathways of mCDW towards grounding lines are crucial as they directly control the heat reaching the ice. A realistic representation of mCDW circulation, however, remains challenging due to the sparsity of in-situ observations and the difficulty of ocean models to reproduce the available observations. In this study, we use an unprecedentedly high-resolution (200 m horizontal and 10 m vertical grid spacing) ocean model that resolves shelf-sea and sub-ice-shelf environments in qualitative agreement with existing observations during austral summer conditions. We demonstrate that the waters reaching the Pine Island and Thwaites grounding lines follow specific, topographically-constrained routes, all passing through a relatively small area located around 104°W and 74.3°S. The temporal and spatial variabilities of ice shelf melt rates are dominantly controlled by the sub-ice shelf ocean current. Our findings highlight the importance of accurate and high-resolution ocean bathymetry and subglacial topography for determining mCDW pathways and ice shelf melt rates.

Additional Information

© 2019 The Author(s). This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/. Received 20 May 2019; Accepted 21 October 2019; Published 22 November 2019. The research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration (NASA). Support was provided by an appointment to the NASA Postdoctoral Program; the NASA Cryosphere program; and the NASA Modeling, Analysis, and Prediction program. Computations were carried out at the NASA Advanced Supercomputing facilities. This work was also supported by the fund from Grant in Aids for Scientific Research (19K23447) of the Japanese Ministry of Education, Culture, Sports, Science and Technology. We thank Peter Davis, Keith Nicholls, Karen Heywood, Ben Webber, Adrian Jenkins, David Shean, Susheel Adusumilli, Stan Jacobs for their support for finding and accessing observational datasets. We also thank the infection of Yoshihiro Nakayama's ear during his vacation to give him a great opportunity to work on this simulation. Data availability: The model code and daily outputs are available at https://ecco.jpl.nasa.gov/drive/files/ECCO2/High_res_PIG. Each user must first register for an Earthdata account at https://urs.earthdata.nasa.gov/users/new in order to access these files. Author Contributions: Y.N. conceived the study, conducted the ocean modeling, and wrote the initial draft of the paper. D.M. and H.Z. contributed to the global LLC270 optimization and helped with regional model set-up. Y.N., G.M., H.Z., H.G.T., P.K., P.D., H.S., M.S., E.R. and D.M. discussed the results and implications and commented on the manuscript at all stages. The authors declare no competing interests.

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Published - s41598-019-53190-6.pdf

Supplemental Material - 41598_2019_53190_MOESM1_ESM.pdf


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August 19, 2023
October 20, 2023