High-Spatial Resolution Mascon Solution Over High Mountain Asia Constrained by Multisource Prior Information

High mountain Asia (HMA) holds the largest concentration of glaciers outside the polar regions, and the melting glaciers provide freshwater for more than one billion people. Therefore, it is crucial to estimate glacier mass changes over HMA. Though Gravity Recovery and Climate Experiment (GRACE) and GRACE Follow-On (GRACE-FO) can accurately monitor monthly global mass changes, the low spatial resolution of ∼300 km limits the ability to reveal detailed spatiotemporal characteristics of mountain glacier changes. In this contribution, we derived a high-resolution (0.5°×0.5°) mascon (mass concentration) solution from April 2002 to August 2023, which is innovatively constrained by multisource prior information from advanced spaceborne thermal emission and reflection radiometer, satellite altimetry, and WaterGAP global hydrology model. Therefore, the developed mascon solution shows higher spatial resolution than the three state-of-the-art global mascon solutions regarding the spatial distribution of mass change trends. Moreover, our mascon solution is highly correlated with in situ measurements at four stations compared to the three mascon solutions in capturing the interannual mass variations with an average correlation coefficient of 0.60. Then, we further investigate the spatiotemporal mass change characteristics in HMA with the developed high-spatial resolution mascon solution. Results show that the Central Himalayas, Western Himalayas, and Nyainqentanglha experienced the most substantial losses from 2002 to 2023, with trends of 5.46 ± 0.42, 3.92 ± 0.80, and 3.79 ± 1.20 Gt/yr, respectively. Additionally, seasonal variations’ magnitudes and temporal patterns vary with regions, exhibiting significant spatial heterogeneity. Our high-spatial resolution mascon solution provides valuable records, unveiling mass changes and potential glacier instability hidden in low-spatial resolution solutions. This enhancement strengthens the capabilities of GRACE/GRACE-FO in comprehending the global glacier response to climate change.