Cross-Mission Synergy of ICESat and ICESat-2 for Estimating Greenland Ice Sheet Elevation Change From 2003 to 2020

Greenland Ice Sheet is one of the key factors influencing global climate change. Its slight variations can lead to significant changes in sea level, making quantitative research on its mass balance of great scientific importance. This study employs ICESat and ICESat-2 satellite altimetry data from NASA’s ICESat (2003-2009) and ICESat-2 (2018-2020) missions to systematically quantify ice sheet elevation dynamics and associated to volumetric changes between 2003 and 2020, To mitigate intra-annual variability effects, analysis was constrained to temporally homologous quarter (January to April), ensuring interannual comparability through consistent seasonal sampling. The results indicate:1. From 2003 to 2008, the average elevation change rate of the Greenland Ice Sheet was -10.65 ± 3.20 cm/yr, with an average volume change rate of -183.31 ± 51.43 km³/yr. Elevation-related mass divergence was observed with near-equilibrium condition prevailing above 2000 m asl, whereas sub-2000 m elevations exhibited pronounced ablation. Maximum depletion was concentrated in southeast basin at -86.38 km³/yr. 2. From 2003 to 2020, the average elevation change rate was -14.60 ± 1.06 cm/yr, and the average volume change rate was -251.97 ± 18.05 km³/yr. Near-equilibrium condition remained above 2000 m asl, while northeast basin exhibited mass increasement above 2000 m asl compared to 2003-2008 and the southeast and northwest basins showed significant decrease. 3. The elevation change rate of 2003-2020 is more negative than that of 2003-2019, which may cause by intense melting events in Greenland Ice Sheet in 2019.