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ToolsWild, Christian T., Snow, Tasha, Dotto, Tiago S., Davis, Peter E. D., Tyler, Scott, Scambos, Ted A., Pettit, Erin C. and Heywood, Karen J. (2025) Thwaites Eastern Ice Shelf cavity observations reveal multiyear sea ice dynamics and deepwater warming in Pine Island Bay, West Antarctica. Ocean Science, 21 (5). pp. 2605-2629. ISSN 1812-0784
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Abstract
Pine Island Bay (PIB), situated in the Amundsen Sea, is renowned for its retreating ice shelves and highly variable sea ice. While brine rejection from sea ice formation and glacial meltwater influence seawater properties, the downstream impacts beneath the region's floating ice shelves remain poorly understood. Here, we exploit an unprecedented multiyear (2020–2023) oceanographic time series from instruments deployed through boreholes beneath the Thwaites Eastern Ice Shelf (TEIS), immediately downstream of PIB, offering new insight into how ice–ocean–atmosphere interactions in PIB shape oceanographic conditions within the subshelf cavity. Our observations reveal a sustained warming and thickening of the modified Circumpolar Deep Water (mCDW) layer near the seabed since January 2020, critical in a region where mCDW drives basal melting beneath West Antarctica's most vulnerable outlet glaciers. Concurrently, the retreat of the multiyear sea ice edge by over 150 km across most of PIB has enhanced the advection of Winter Water, contributing to a cooling of more than 1 °C in the upper 250 m beneath TEIS between July 2021 and January 2023. Superimposed on these trends are episodic temperature and salinity anomalies lasting several weeks, originating in PIB and advecting past the moorings. These events link mobile sea ice cover to subshelf hydrography, as mid-depth waters temporarily warm and increase in salinity, leading to an increase in density, while deeper mCDW simultaneously cools and freshens, reducing its density. Overall, these changes are associated with reduced stratification in the cavity. As sea ice continues to decline in a warming Antarctic climate, our results offer a glimpse into how ocean circulation and basal melting may evolve across the Amundsen Sea Embayment. This dataset provides a critical benchmark for refining process-based models and improving melt rate parameterizations in coupled ice–ocean simulations.
| Item Type: | Article |
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| Additional Information: | Code availability: Python code for retrieving daily sea ice concentration can be found at https://github.com/tsnow03/thwaites_amigos (last access: 24 October 2025; DOI: https://doi.org/10.5281/zenodo.17328677, Snow, 2025). The MATLAB Gibbs-SeaWater (GSW) Oceanographic Toolbox is available from http://www.teos-10.org/ (last access: 20 November 2023). MATLAB software for wavelet analysis can be found at https://github.com/grinsted/wavelet-coherence (Grinsted, 2025; Grinsted et al., 2004). Data availability: The AMIGOS-3, borehole CTD, and DTS data from Cavity Camp and Channel Camp are available from the United States Antarctic Program Data Center (USAP-DC) at https://www.usap-dc.org/view/project/p0010162 (last access: 9 October 2025). The ship-based CTD dataset from February 2019 is available at https://www.bodc.ac.uk/data/published_data_library/catalogue/10.5285/e338af5d-8622-05de-e053-6c86abc06489/ (last access: 24 October 2025). Autonomous underwater vehicle data are available at https://doi.org/10.5878/yw26-vc65 (Wåhlin, 2021; Wåhlin et al., 2021). ERA5 reanalysis data are available from https://doi.org/10.24381/cds.adbb2d47 (Hersbach et al., 2023). Sentinel-1 SAR data are freely available from https://browser.dataspace.copernicus.eu/ (last access: 9 October 2025) upon registration (ESA et al., 2020). The sea ice concentration dataset is available from the University of Bremen at https://data.seaice.uni-bremen.de/amsr2/asi_daygrid_swath/s3125/ (last access: 9 October 2025). Funding information: This research has been supported by the National Science Foundation, Directorate for Geosciences (grant no. 1929991), and the Natural Environment Research Council (grant no. NE/S006419/1). Christian T. Wild was partially supported by the Deutsche Forschungsgemeinschaft (DFG) in the framework of the priority program 1158 “Antarctic Research with comparative investigations in Arctic ice areas” (grant no. DR 822/8-1). Tiago S. Dotto was also supported by the UK Natural Environment Research Council National Capability program AtlantiS (grant no. NE/Y005589/1). This open-access publication was funded by the Open Access Publication Fund of the University of Tübingen. |
| Faculty \ School: | Faculty of Science > School of Environmental Sciences University of East Anglia Research Groups/Centres > Theme - ClimateUEA |
| UEA Research Groups: | Faculty of Science > Research Groups > Centre for Ocean and Atmospheric Sciences |
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| Depositing User: | LivePure Connector |
| Date Deposited: | 28 Oct 2025 13:30 |
| Last Modified: | 28 Oct 2025 13:30 |
| URI: | https://ueaeprints.uea.ac.uk/id/eprint/100818 |
| DOI: | 10.5194/os-21-2605-2025 |
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