USAP-DC

In contrast to the Arctic, sea ice cover in most Antarctic regions has increased since 1979. The area-integrated total sea ice extent grew to record maximum values in four of the last six years, yet the 2015-16 summer was marked by record low ice cover. While impressive, it is difficult to assess the significance of these very recent records in the context of longer term variability, since the continuous satellite record only dates back to 1978. The limited length of the continuous sea ice record, is a significant confounding factor in ascertaining whether the observed current changes are due to natural variability alone, or represent a forced anthropogenic response. As a result, the scientific understanding of the Antarctic sea ice trends remains poor, as does confidence in projections of future Antarctic sea ice trends. To address this challenge, this project seeks to reconstruct sea ice extent and sea ice concentration, using the relationships between satellite-observed sea ice, sea level pressure, tropical sea surface temperature, ENSO indices, some proxy data (ice cores, etc.), and in situ Southern Ocean temperature data. The aim of the study is to collect and combine these ancillary records as accurately as possible while retaining the variability associated with the intrinsic uncertainty in the available field data. A range of statistical methods for modelling the relationship between satellite era sea-ice data using flexible regression, Bayesian and multivariate dynamic spatial temporal (MDST) methods will be used. The study will entrain cross-disciplinary training of undergraduate and a graduate student at UCLA and Ohio University. 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
Fogt, Ryan	Investigator and contact

Antarctic Ocean and Atmospheric Sciences	Award # 1745089
Antarctic Ocean and Atmospheric Sciences	Award # 1744998

USAP-1744998_1

None in the Database

Repository	Title (link)	Format(s)	Status
Figshare	Antarctic Sea Ice Reconstructions	Not Provided	exists

1. Fogt, R., Dalaiden, Q., & O’Connor, G. (2023). A Comparison of South Pacific Antarctic Sea Ice and Atmospheric Circulation Reconstructions Since 1900. (doi:10.5194/cp-2023-63)
2. Marshall, G. J., Fogt, R. L., Turner, J., & Clem, K. R. (2022). Can current reanalyses accurately portray changes in Southern Annular Mode structure prior to 1979? Climate Dynamics. (doi:10.1007/s00382-022-06292-3)
3. Fogt, R. L., & Marshall, G. J. (2020). The Southern Annular Mode: Variability, trends, and climate impacts across the Southern Hemisphere. WIREs Climate Change, 11(4). (doi:10.1002/wcc.652)
4. Clem, K. R., Fogt, R. L., Turner, J., Lintner, B. R., Marshall, G. J., Miller, J. R., & Renwick, J. A. (2020). Record warming at the South Pole during the past three decades. Nature Climate Change, 10(8), 762–770. (doi:10.1038/s41558-020-0815-z)
5. Fogt, R. L., Belak, C. P., Jones, J. M., Slivinski, L. C., & Compo, G. P. (2020). An assessment of early 20th century Antarctic pressure reconstructions using historical observations. International Journal of Climatology, 41(S1). (doi:10.1002/joc.6718)
6. Handcock, M. S., & Raphael, M. N. (2020). Modeling the annual cycle of daily Antarctic sea ice extent. The Cryosphere, 14(7), 2159–2172. (doi:10.5194/tc-14-2159-2020)
7. Handcock, M. S., & Raphael, M. N. (2019). Modeling the annual cycle of daily Antarctic sea ice extent. (doi:10.5194/tc-2019-203)
8. Raphael, M., Handcock, M. S., Holland, M. M., & Landrum, L. L. (2020). An assessment of the temporal variability in the annual cycle of daily Antarctic sea ice in the NCAR Community Earth System Model, Version 2: A comparison of the historical runs with observations. (doi:10.1002/essoar.10503305.1)
9. Fogt, R. L., Dalaiden, Q., & O’Connor, G. K. (2024). A comparison of South Pacific Antarctic sea ice and atmospheric circulation reconstructions since 1900. Climate of the Past, 20(1), 53–76. (doi:10.5194/cp-20-53-2024)