Estimation of snow depth on sea ice surface with ice-type-dependent constraints in the Weddell Sea using ICESat-2 and CryoSat-2

Accurate measurement of snow depth (SD) on the sea ice surface is essential for polar climate and environmental research. The SD estimation method based on the freeboard difference between ICESat-2 and CryoSat-2 suffers from systematic bias due to the penetration depth of the CryoSat-2 Ku-band in the snow layer. This study introduces an ice-type-dependent linear constraint method designed to calibrate the CryoSat-2 sea ice freeboard using actual onboard Operation IceBridge measurements. This approach enhances the accuracy of SD estimation, achieving a reduction in RMSE of up to 3.01 cm. Based on this improvement, a high-resolution, along-track SD dataset for the Weddell Sea from 2019 to 2024 is generated through rigorous spatio-temporal matching. Analysis reveals key features: 1) the multi-year mean SD in the region is 23.5 cm, with inter-monthly fluctuations not exceeding 13.7 cm, 2) the eastern region is characterized by seasonal ice, exhibiting a shallower SD (18.9 cm), smooth inter-annual variability (<5.9 cm), and distinct seasonal patterns, and 3) conversely, the western zone is dominated by multi-year ice, presenting a greater SD (29.2 cm), notable interannual fluctuations of up to 14 cm, and seasonal variations influenced by a combination of multiple ice types and dynamic ice processes. The proposed method improves the SD estimation accuracy and provides an important reference for understanding the dynamics of the Antarctic sea ice-snow system and its climate response.