Surface Motion and Topographic Effects on Ice Thickness Inversion for High Mountain Asia Glaciers: A Comparison Study from Three Numerical Models

Several studies have evaluated the accuracy of ice thickness model inversions, but the effects of surface velocity and topographic factors have not been fully studied. Because of the important potential of models for estimating regional and global ice thickness, the influence of the characteristics of the glaciers themselves on the models is unknown. Therefore, we estimated the thickness of 10 glaciers in HMA based on remote sensing data using the GlabTop2, GV22, and VOLTA models, and we analyzed the factors affecting accuracy. The first two models are representative of the widely used shallow ice approximation and laminar flow theory, and the latter is a new model based on shallow ice approximation. The results show that the RMSEs for GlabTop2, VOLTA, and GV22 are 36.6 m, 56.8 m, and 63.2 m, respectively. The accuracy of the three models differed obviously under the influence of different slopes, aspects, and surface velocities. In contrast to glaciers with higher surface velocities, GV22 is more suitable for glaciers with smaller surface velocities, and the accuracy of the model is significantly reduced when surface velocities are greater than 50 m/yr. Aspect has an effect on the accuracy of the GV22 ice thickness inversion but not on the other models. Ice thicknesses estimated using the three models is more reliable at surface slopes of 16–24°. These three models do not apply to gentle glaciers such as icecaps. Our study provides an important reference for choosing a suitable model to invert the glacier thickness in HMA.