Ross Gyre variability modulates oceanic heat supply toward the West Antarctic continental shelf

Creators: Prend, Channing J.; MacGilchrist, Graeme A.; Manucharyan, Georgy E.; Pang, Rachel Q.; Moorman, Ruth; Thompson, Andrew F.¹; Griffies, Stephen M.; Mazloff, Matthew R.; Talley, Lynne D.; Gille, Sarah T.

1. California Institute of Technology

Abstract

West Antarctic Ice Sheet mass loss is a major source of uncertainty in sea level projections. The primary driver of this melting is oceanic heat from Circumpolar Deep Water originating offshore in the Antarctic Circumpolar Current. Yet, in assessing melt variability, open ocean processes have received considerably less attention than those governing cross-shelf exchange. Here, we use Lagrangian particle release experiments in an ocean model to investigate the pathways by which Circumpolar Deep Water moves toward the continental shelf across the Pacific sector of the Southern Ocean. We show that Ross Gyre expansion, linked to wind and sea ice variability, increases poleward heat transport along the gyre’s eastern limb and the relative fraction of transport toward the Amundsen Sea. Ross Gyre variability, therefore, influences oceanic heat supply toward the West Antarctic continental slope. Understanding remote controls on basal melt is necessary to predict the ice sheet response to anthropogenic forcing.

Copyright and License

© The Author(s) 2024. 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/.

Acknowledgement

C.J.P., G.A.M., M.R.M., L.D.T., and S.T.G. were supported by NSF PLR-1425989 and OPP-1936222 (Southern Ocean Carbon and Climate Observations and Modeling project). C.J.P. received additional support from a NOAA Climate & Global Change Postdoctoral Fellowship. G.A.M. received additional support from UKRI Grant Ref. MR/W013835/1. G.E.M. was supported by NSF OPP-2220969. R.Q.P. was supported by the High Meadows Environmental Institute Internship Program. R.M. was supported by the General Sir John Monash Foundation. A.F.T. was supported by NSF OPP-1644172 and NASA grant 80NSSC21K0916. M.R.M. also acknowledges funding from NSF awards OCE-1924388 and OPP-2319829 and NASA awards 80NSSC22K0387 and 80NSSC20K1076. Thanks to Steve Rintoul and two anonymous reviewers for their helpful comments. Thanks also to Becki Beadling for reading an earlier draft of the manuscript, and to Maike Sonnewald and Mary-Louise Timmermans for useful conversations.

Contributions

C.J.P. designed the study with input and supervision from G.E.M., A.F.T., L.D.T., and S.T.G. M.R.M. developed the model and G.A.M. configured the Lagrangian particle release experiments. C.J.P. and R.Q.P. conducted the rest of the analysis. R.Q.P. received additional supervision from G.A.M. and S.M.G. R.M. provided code and insights on the overall framing of the work. C.J.P. wrote the manuscript. All authors contributed to the interpretation of the results and commented on the manuscript.

Data Availability

Output from the Biogeochemical Southern Ocean State Estimate (B-SOSE) is publicly available (http://sose.ucsd.edu); this analysis utilizes Iteration 133 of the model solution. Offline Lagrangian particle trajectories were calculated using Parcels (http://oceanparcels.org) and are archived on Zenodo (http://zenodo.org/doi/10.5281/zenodo.10393325).

Conflict of Interest

The authors declare no competing interests.

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