USAP-DC

The Antarctic Ice Sheet (AIS) is sensitive to and an indicator of climate change. While ice loss is largely driven by ocean warming, this might be mitigated by enhanced snowfall on the ice sheet. By developing an understanding of the processes governing snowfall variability and change on the AIS, this project will contribute to understanding the long-term role of the AIS as a contributor to sea-level rise. This project is strongly embedded in the collaborative, open-source framework of the Community Earth System Model version 2 (CESM2) and will deliver new datasets of Antarctic precipitation for use by the research community. The project will help to build a diverse geoscience workforce by recruiting and training a student to be directly involved in the research through the Significant Opportunities in Atmospheric Research and Science (SOARS) program. The project will leverage the Climate Model Intercomparison Project 6 climate model ensemble as a whole, and CESM2 in particular, to disentangle the major sources of uncertainty and to elucidate the underlying mechanisms of Antarctic precipitation change, with a particular focus on the role of atmospheric circulation changes relative to the role of atmospheric warming. Using the variable resolution capabilities of CESM2, the team will provide the community with precipitation estimates at a very high horizontal resolution. The analyses will also use a forthcoming 100-member large ensemble. The project seeks to answer the following questions: 1) How well does the CESM2 represent the present-day Antarctic surface climate, precipitation, and surface mass balance, including the mean and its variability? 2) What is the sensitivity of simulated Antarctic precipitation to model resolution in present-day and future climates? 3) What are the roles of thermodynamics (warming atmosphere and ocean) and dynamics (changes in atmospheric circulation) in observed and projected snowfall changes? How do these break down into forced and internal variability? In particular, is there a significant forced precipitation trend due to circulation changes driven by stratospheric ozone depletion and recovery and increases in greenhouse gas concentration? 4) What processes and boundary conditions drive the ensemble spread of Antarctic precipitation in single-model and multi-model ensembles? How does the spread driven by initial surface conditions (including sea ice cover, surface fluxes, inversion strength) compare with the irreducible uncertainty due to internal climate system variability? 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
Schneider, David	Investigator and contact
Datta, Rajashree Tri	Investigator

Antarctic Glaciology	Award # 1952199
Antarctic Integrated System Science	Award # 1952199
Antarctic Ocean and Atmospheric Sciences	Award # 1952199

USAP-1952199_1

None in the Database

Repository	Title (link)	Format(s)	Status
Zenodo	Variable-resolution CESM2 over Antarctica (ANTSI): Monthly outputs used for evaluation	Not Provided	exists

1. Dunmire, D., Lenaerts, J. T. M., Datta, R. T., & Gorte, T. (2022). Antarctic surface climate and surface mass balance in the Community Earth System Model version 2 (1850–2100). (doi:10.5194/tc-2022-52)
2. Wille, J. D., Favier, V., Gorodetskaya, I. V., Agosta, C., Kittel, C., Beeman, J. C., … Codron, F. (2021). Antarctic Atmospheric River Climatology and Precipitation Impacts. Journal of Geophysical Research: Atmospheres, 126(8). (doi:10.1029/2020jd033788)
3. Holland, P. R., O’Connor, G. K., Bracegirdle, T. J., Dutrieux, P., Naughten, K. A., Steig, E. J., Schneider, D. P., Jenkins, A., & Smith, J. A. (2022). Anthropogenic and internal drivers of wind changes over the Amundsen Sea, West Antarctica, during the 20th and 21st centuries. The Cryosphere, 16(12), 5085–5105. (doi:10.5194/tc-16-5085-2022)
4. 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)
5. Schneider, D. P., Kay, J. E., & Hannay, C. (2022). Cloud and Surface Albedo Feedbacks Reshape 21st Century Warming in Successive Generations of An Earth System Model. Geophysical Research Letters, 49(19). Portico. (doi:10.1029/2022gl100653)
6. Dunmire, D., Lenaerts, J. T. M., Datta, R. T., & Gorte, T. (2022). Antarctic surface climate and surface mass balance in the Community Earth System Model version 2 during the satellite era and into the future (1979–2100). The Cryosphere, 16(10), 4163–4184. (doi:10.5194/tc-16-4163-2022)
7. Wille, J. D., Alexander, S. P., Amory, C., Baiman, R., Barthélemy, L., Bergstrom, D. M., Berne, A., Binder, H., Blanchet, J., Bozkurt, D., Bracegirdle, T. J., Casado, M., Choi, T., Clem, K. R., Codron, F., Datta, R., Di Battista, S., Favier, V., Francis, D., … Zou, X. (2024). The Extraordinary March 2022 East Antarctica “Heat” Wave. Part I: Observations and Meteorological Drivers. Journal of Climate, 37(3), 757–778. (doi:10.1175/jcli-d-23-0175.1)
8. Wille, J. D., Alexander, S. P., Amory, C., Baiman, R., Barthélemy, L., Bergstrom, D. M., Berne, A., Binder, H., Blanchet, J., Bozkurt, D., Bracegirdle, T. J., Casado, M., Choi, T., Clem, K. R., Codron, F., Datta, R., Battista, S. D., Favier, V., Francis, D., … Zou, X. (2024). The Extraordinary March 2022 East Antarctica “Heat” Wave. Part II: Impacts on the Antarctic Ice Sheet. Journal of Climate, 37(3), 779–799. (doi:10.1175/jcli-d-23-0176.1)
9. Holland, P., O’Connor, G., Bracegirdle, T., Dutrieux, P., Naughten, K., Steig, E., Schneider, D., Jenkins, A., & Smith, J. (2022). Anthropogenic and internal drivers of wind changes over the Amundsen Sea, West Antarctica, during the 20th and 21st centuries. (doi:10.5194/tc-2022-121)