Ten Years of Antarctic Sea Ice Thickness Estimates from CryoSat-2 Using a Physical Model and Waveform-fitting

Altimetric estimates of Antarctic sea ice thickness remain limited, partially due to inadequate knowledge of the depth and impact of the overlying snow layer. While data from laser altimeters, such as NASAs Ice, Cloud, and land Elevation Satellite (ICESat) and ICESat-2, have been used to estimate thickness by employing certain assumptions with the snow surface range (e.g. that the snow freeboard is equal to the snow depth), radar-altimetry-derived estimates have been hindered by less-certain knowledge of the dominant scattering interface and a lack of constraint on the total snow loading. This hindrance has led to a deficiency of Antarctic sea ice thickness estimates in the decade-plus covering the CryoSat-2 mission. Here, we showcase efforts towards addressing the need for Antarctic sea ice thickness estimates over the CryoSat-2 mission. A physical model and waveform-fitting method are used to retrieve the snow freeboard of Antarctic sea ice, which has shown good agreement to that from ICESat-2 [Fons et al. 2021]. By combining both the snow freeboard and snow depth from the physical model, we are able to estimate the sea ice thickness. These exploratory estimates are compared against those from other works and analyzed over the 10 years from 2010 to 2020. Regional and seasonal trends in the data are also shown. Finally, this work presents these thickness estimates in the context of a longer (18+ year) altimetric time series spanning from ICESat to CryoSat-2 and ICESat-2, and discusses potential avenues for inter-mission reconciliation. Fons, S. W., Kurtz, N. T., Bagnardi, M., Petty, A. A., & Tilling, R. L. (2021). Assessing CryoSat-2 Antarctic snow freeboard retrievals using data from ICESat-2. Earth and Space Science, 8, e2021EA001728. https://doi.org/10.1029/2021EA001728