Deriving Antarctic Sea-Ice Thickness From Satellite Altimetry and Estimating Consistency for NASA's ICESat/ICESat-2 Missions

With the launch of the Ice, Cloud and Land Elevation Satellite-2 (ICESat-2), densely measuring the Antarctic ocean all year long, monthly sea ice thickness changes can be inspected. However, the consistency between ICESat-2 and its predecessor ICESat remains unknown if a long-term change of the Antarctic sea ice thickness is to be examined. Due to the complex physical structure of Antarctic sea ice, an improved One-Layer Method (OLMi) for sea-ice thickness retrieval, with an ∼0.3 m uncertainty, is proposed in this study. Using this method, the monthly sea ice variation in each sea sector of Antarctica from ICESat-2 is inspected, revealing detailed characteristics of Antarctic sea ice over sector scale such as bi-modal distributions. The different retrieving methods for the total freeboard from ICESat are found to be ∼0.036 m lower than that from ICESat-2. The circum-Antarctic sea ice thickness shows a decreasing tendency (2003–2020), especially in summer with −0.014 m/yr.