USAP-DC

Ice-core records are critical to understanding past climate variations. An Antarctic ice core currently being drilled at the South Pole will allow detailed investigation of atmospheric gases and fill an important gap in understanding the pattern of climate variability across Antarctica. Critical to the interpretation of any ice core are: 1) accurate chronologies for both the ice and the trapped gas and 2) demonstration that records from the ice core reliably reflect climate. The proposed research will improve the ice and gas chronologies by making measurements of snow compaction in the upstream catchment in order to constrain age models of the ice. These measurements will be a key data set needed for better understanding and predicting time-varying conditions in the upper part of the ice sheet. The research team will measure the modern spatial gradients in accumulation rate, surface temperature, and water stable isotopes from shallow ice cores in the upstream catchment in order to determine the climate history from the ice-core record. The new ice-flow measurements will make it possible to define the path of ice from upstream to the South Pole ice-core drill site to assess spatial gradients in snowfall and to infer histories of snowfall from internal layers within the ice sheet. The project will be led by an early-career scientist, provide broad training to graduate students, and engage in public outreach on polar science.

Ice-core records of stable isotopes, aerosol-born particles, and atmospheric gases are critical to understanding past climate variations. The proposed research will improve the ice and gas chronologies in the South Pole ice core by making in situ measurements of firn compaction in the upstream catchment to constrain models of the gas-age ice-age difference. The firn measurements will be a key data set needed to form a constitutive relationship for firn, and will drive better understanding and prediction of transient firn evolution. The research team will measure the modern gradients in accumulation rate, surface temperature, and water stable isotopes in the upstream catchment to separate spatial (advection) variations from temporal (climate) variations in the ice-core records. The ice-flow measurements will define the flowline upstream of the drill site, assess spatial gradients in accumulation, and infer histories of accumulation from radar-observed internal layers. Results will directly enhance interpretation of South Pole ice-core records, and also advance understanding of firn densification and drive next-generation firn models.

Person	Role
Koutnik, Michelle	Investigator
Conway, Howard	Co-Investigator
Waddington, Edwin D.	Co-Investigator
Fudge, T. J.	Co-Investigator
Hawley, Robert L.	Investigator
Osterberg, Erich	Co-Investigator

Antarctic Glaciology	Award # 1443471
Antarctic Glaciology	Award # 1443341

USAP-1443471_1

None in the Database

Repository	Title (link)	Format(s)	Status
USAP-DC	Shallow radar near South Pole	CSV	exist
USAP-DC	South Pole area GPS velocities	CSV	exist
USAP-DC	SPICEcore Advection	CSV	exists
USAP-DC	7MHz radar in the vicinity of South Pole	CSV	exists
USAP-DC	Firn temperatures 50km upstream of South Pole	CSV	exists
USAP-DC	Firn density and compaction rates 50km upstream of South Pole	CSV	exists

1. Lilien, D. A., Fudge, T. J., Koutnik, M. R., Conway, H., Osterberg, E. C., Ferris, D. G., … Stevens, C. M. (2018). Holocene Ice-Flow Speedup in the Vicinity of the South Pole. Geophysical Research Letters, 45(13), 6557–6565. (doi:10.1029/2018gl078253)
2. Kahle, E. C., Steig, E. J., Jones, T. R., Fudge, T. J., Koutnik, M. R., Morris, V., … White, J. W. C. (2020). Reconstruction of temperature, accumulation rate, and layer thinning from an ice core at South Pole using a statistical inverse method. (doi:10.1002/essoar.10503447.1)
3. Stevens, C. M., Verjans, V., Lundin, J. M. D., Kahle, E. C., Horlings, A. N., Horlings, B. I., & Waddington, E. D. (2020). The Community Firn Model (CFM) v1.0. Geoscientific Model Development, 13(9), 4355–4377. (doi:10.5194/gmd-13-4355-2020)
4. Stevens, C. M., Verjans, V., Lundin, J. M. D., Kahle, E. C., Horlings, A. N., Horlings, B. I., & Waddington, E. D. (2020). The Community Firn Model (CFM) v1.0. (doi:10.5194/gmd-2019-361)
5. Kahle, E. C., Steig, E. J., Jones, T. R., Fudge, T. J., Koutnik, M. R., Morris, V., … White, J. W. C. (2021). Reconstruction of temperature, accumulation rate, and layer thinning from an ice core at South Pole using a statistical inverse method. (doi:10.1002/essoar.10503447.2)
6. Kahle, E. C., Steig, E. J., Jones, T. R., Fudge, T. J., Koutnik, M. R., Morris, V. A., … White, J. W. C. (2021). Reconstruction of Temperature, Accumulation Rate, and Layer Thinning From an Ice Core at South Pole, Using a Statistical Inverse Method. Journal of Geophysical Research: Atmospheres, 126(13). (doi:10.1029/2020jd033300)
7. Keegan, K. M., Albert, M. R., McConnell, J. R., & Baker, I. (2019). Climate Effects on Firn Permeability Are Preserved Within a Firn Column. Journal of Geophysical Research: Earth Surface, 124(3), 830–837. (doi:10.1029/2018jf004798)
8. Kahle, E. C., Steig, E. J., Jones, T. R., Fudge, T. J., Koutnik, M. R., Morris, V., Vaughn, B., Schauer, A., Stevens, C. M., Conway, H., Waddington, E. D., Buizert, C., Epifanio, J., & White, J. W. C. (2021). Reconstruction of temperature, accumulation rate, and layer thinning from an ice core at South Pole using a statistical inverse method. (doi:10.1002/essoar.10503447.3)
9. Oster, S. E., & Albert, M. R. (2022). Thermal conductivity of polar firn. Journal of Glaciology, 1–8. (doi:10.1017/jog.2022.28)
10. Stevens, C. M., Lilien, D. A., Conway, H., Fudge, T. J., Koutnik, M. R., & Waddington, E. D. (2023). A new model of dry firn-densification constrained by continuous strain measurements near South Pole. Journal of Glaciology, 1–15. (doi:10.1017/jog.2023.87)