USAP-DC

This project contributes to the joint initiative launched by the U.S. National Science Foundation (NSF) and the U.K. Natural Environment Research Council (NERC) to substantially improve decadal and longer-term projections of ice loss and sea-level rise originating from Thwaites Glacier in West Antarctica. Thwaites and neighboring glaciers in the Amundsen Sea Embayment are rapidly losing mass in response to recent climate warming and related changes in ocean circulation. Mass loss from the Amundsen Sea Embayment could lead to the eventual collapse of the West Antarctic Ice Sheet, raising the global sea level by up to 2.5 meters (8 feet) in as short as 500 years. The processes driving the loss appear to be warmer ocean circulation and changes in the width and flow speed of the glacier, but a better understanding of these changes is needed to refine predictions of how the glacier will evolve. One highly sensitive process is the transitional flow of glacier ice from land onto the ocean to become a floating ice shelf. This flow of ice from grounded to floating is affected by changes in air temperature and snowfall at the surface; the speed and thickness of ice feeding it from upstream; and the ocean temperature, salinity, bathymetry, and currents that the ice flows into. The project team will gather new measurements of each of these local environmental conditions so that it can better predict how future changes in air, ocean, or the ice will affect the loss of ice to the ocean in this region.

Current and anticipated near-future mass loss from Thwaites Glacier and nearby Amundsen Sea Embayment region is mainly attributed to reduction in ice-shelf buttressing due to sub-ice-shelf melting by intrusion of relatively warm Circumpolar Deep Water into sub-ice-shelf cavities. Such predictions for mass loss, however, still lack understanding of the dominant processes at and near grounding zones, especially their spatial and temporal variability, as well as atmospheric and oceanic drivers of these processes. This project aims to constrain and compare these processes for the Thwaites and the Dotson Ice Shelves, which are connected through upstream ice dynamics, but influenced by different submarine troughs. The team's specific objectives are to: 1) install atmosphere-ice-ocean multi-sensor remote autonomous stations on the ice shelves for two years to provide sub-daily continuous observations of concurrent oceanic, glaciologic, and atmospheric conditions; 2) measure ocean properties on the continental shelf adjacent to ice-shelf fronts (using seal tagging, glider-based and ship-based surveys, and existing moored and conductivity-temperature-depth-cast data), 3) measure ocean properties into sub-ice-shelf cavities (using autonomous underwater vehicles) to detail ocean transports and heat fluxes; and 4) constrain current ice-shelf and sub-ice-shelf cavity geometry, ice flow, and firn properties for the ice-shelves (using radar, active-source seismic, and gravimetric methods) to better understand the impact of ocean and atmosphere on the ice-sheet change. The team will also engage the public and bring awareness to this rapidly changing component of the cryosphere through a "Live from the Ice" social media campaign in which the public can follow the action and data collection from the perspective of tagged seals and autonomous stations.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

Person	Role
Truffer, Martin	Co-Investigator
Scambos, Ted	Co-Investigator
Muto, Atsu	Co-Investigator
Alley, Karen	Researcher
Heywood, Karen	Co-Investigator
Wild, Christian	Researcher
Boehme, Lars	Co-Investigator
Hall, Robert	Co-Investigator
Wahlin, Anna	Co-Investigator
Lenaerts, Jan	Co-Investigator
Pettit, Erin	Investigator and contact

Antarctic Glaciology	Award # 1929991
Antarctic Integrated System Science	Award # 1929991
Antarctic Ocean and Atmospheric Sciences	Award # 1929991
Antarctic Glaciology	Award # 1738992
Antarctic Integrated System Science	Award # 1738992
Antarctic Ocean and Atmospheric Sciences	Award # 1738992

USAP-1929991_1

Deployment	Type
Thwaites Eastern Ice Shelf	field camp

None in the Database

Repository	Title (link)	Format(s)	Status
USAP-DC	Two-year velocity and strain-rate averages from the Thwaites Eastern Ice Shelf, 2001-2020	GeoTiff	deprecated
USAP-DC	Two-year velocity and strain-rate averages from the Thwaites Eastern Ice Shelf, 2001-2020	GeoTiff	exists
International Federation of Digital Seismograph Networks	SIIOS Temporary Deployment	Not Provided	exists
USAP-DC	Thwaites Glacier grounding lines for 2014 and 2019/20 from height above flotation	ASCII; shapefile	exists
USAP-DC	AMIGOS-IIIa "Cavity" Seabird CTD data Jan 2020 - Dec 2021	ASCII	exists
USAP-DC	AMIGOS-IIIc "Channel" Seabird CTD data Jan 2020 - Dec 2021	ASCII	exists
USAP-DC	AMIGOS-IIIa "Cavity" Aquadopp current data Jan 2020 - Mar 2021	ASCII	exists
USAP-DC	AMIGOS-IIIc "Channel" Aquadopp current data Jan 2020 - Mar 2021	ASCII	exists
USAP-DC	Visala WXT520 weather station data at the Cavity and Channel AMIGOS-III sites	ASCII	exists
USAP-DC	AMIGOS-III Cavity and Channel Snow Height and Thermistor Snow Temperature Data	ASCII	exists
USAP-DC	Dotson-Crosson Ice Shelf data from a tale of two ice shelves paper	GeoTiff; csv	exists
British Oceanographic Data Centre	CTD data from the NBP 19/02 cruise as part of the TARSAN project in the Amundsen Sea during austral summer 2018/2019	CSV	exists

1. Alley, K. E., Wild, C. T., Luckman, A., Scambos, T. A., Truffer, M., Pettit, E. C., … Dunmire, D. (2021). Two decades of dynamic change and progressive destabilization on the Thwaites Eastern Ice Shelf. (doi:10.5194/tc-2021-76)
2. Boehme, L., & Rosso, I. (2021). Classifying Oceanographic Structures in the Amundsen Sea, Antarctica. Geophysical Research Letters, 48(5). (doi:10.1029/2020gl089412)
3. Wåhlin, A. K., Graham, A. G. C., Hogan, K. A., Queste, B. Y., Boehme, L., Larter, R. D., … Heywood, K. J. (2021). Pathways and modification of warm water flowing beneath Thwaites Ice Shelf, West Antarctica. Science Advances, 7(15), eabd7254. (doi:10.1126/sciadv.abd7254)
4. Wild, C. T., Alley, K. E., Muto, A., Truffer, M., Scambos, T. A., & Pettit, E. C. (2022). Weakening of the pinning point buttressing Thwaites Glacier, West Antarctica. The Cryosphere, 16(2), 397–417. (doi:10.5194/tc-16-397-2022)
5. Wild, C. T., Alley, K. E., Muto, A., Truffer, M., Scambos, T. A., & Pettit, E. C. (2021). Weakening of the pinning point buttressing Thwaites Glacier, West Antarctica. (doi:10.5194/tc-2021-130)
6. Maclennan, M. L., & Lenaerts, J. T. M. (2021). Large‐Scale Atmospheric Drivers of Snowfall Over Thwaites Glacier, Antarctica. Geophysical Research Letters, 48(17). (doi:10.1029/2021gl093644)
7. Savidge, E., Snow, T., Siegfried, M. R., Zheng, Y., Villas Bôas, A. B., Bortolotto, G. A., Boehme, L., & Alley, K. E. (2023). Wintertime Polynya Structure and Variability from Thermal Remote Sensing and Seal-borne Observations at Pine Island Glacier, West Antarctica. IEEE Transactions on Geoscience and Remote Sensing, 1–1. (doi:10.1109/tgrs.2023.3271453)
8. Alley, K. E., Wild, C. T., Luckman, A., Scambos, T. A., Truffer, M., Pettit, E. C., … Dunmire, D. (2021). Two decades of dynamic change and progressive destabilization on the Thwaites Eastern Ice Shelf. The Cryosphere, 15(11), 5187–5203. (doi:10.5194/tc-15-5187-2021)
9. Karplus, M. S., Young, T. J., Anandakrishnan, S., Bassis, J. N., Case, E. H., Crawford, A. J., Gold, A., Henry, L., Kingslake, J., Lehrmann, A. A., Montaño, P. A., Pettit, E. C., Scambos, T. A., Sheffield, E. M., Smith, E. C., Turrin, M., & Wellner, J. S. (2023). Strategies to build a positive and inclusive Antarctic field work environment. Annals of Glaciology, 1–7. (doi:10.1017/aog.2023.32)
10. Maclennan, M. L., Lenaerts, J. T. M., Shields, C. A., Hoffman, A. O., Wever, N., Thompson-Munson, M., Winters, A. C., Pettit, E. C., Scambos, T. A., & Wille, J. D. (2022). Climatology and Surface Impacts of Atmospheric Rivers on West Antarctica. (doi:10.5194/tc-2022-101)
11. Maclennan, M. L., Lenaerts, J. T. M., Shields, C., & Wille, J. D. (2022). Contribution of Atmospheric Rivers to Antarctic Precipitation. Geophysical Research Letters, 49(18). Portico. (doi:10.1029/2022gl100585)