High-Temporal-Resolution Three-Dimensional Glacier Velocity Time Series and Their Implications for Glacier Dynamic Processes in Mt. Tomur, Tian Shan

High-temporal-resolution three-dimensional glacier velocity measurements are essential for unraveling complex ice dynamics, enabling precise monitoring of climate-driven glacier response. In this study, we measured three-dimensional glacier velocity time series in Mt. Tomur at weekly temporal resolution, using the SPO-MSBAS method applied to Sentinel-1 ascending and descending SLC images. In Mt. Tomur, horizontal glacier velocities showed clear directional patterns shaped by topography, with dominant east-west movement and notable north-south components. Vertically, the predominately downward flow across the glacierized areas suggests that ablation rates have exceeded emergence velocities, indicating the imbalance response to ongoing climatic warming. Glacier velocities showed pronounced spatial heterogeneity, varying significantly with elevation, glacier size, and topography, with an average velocity of 44.43 m/yr. Distinct seasonal variations manifested as a fast spring/summer period and a slow winter period, a pattern primarily driven by hydrological controls. In some years, a secondary acceleration was observed from late summer to early autumn, which was brief and weaker in magnitude, likely resulting from gradual closure of the drainage system and consequent basal sliding enhancement. Two distinct glacier acceleration events were observed: (1) a surge event on G079906E42284N Glacier (May-August 2018) with velocity increasing from 0.30 m/d to 1.10 m/d within 9-15 km along the main flowline; (2) an ice collapse event on the northeast tributary of Tuge Biliqi Glacier in December 2017, during which ice velocity accelerated from 0.22 m/d to 0.62 m/d, and the fallen ice and debris subsequently migrated downglacier, as confirmed by optical imagery. These findings demonstrate the critical value of high-temporal-resolution glacier monitoring.