Supraglacial debris thickness variability: impact on ablation and relation to terrain properties

摘要: Abstract. Shallow ground-penetrating radar (GPR) surveys are used to characterize the small-scale spatial variability of supraglacial debris thickness on a Himalayan glacier. Debris thickness varies widely over short spatial scales. Comparison across sites and glaciers suggests that the skewness kurtosis debris frequency distribution decrease with increasing mean thickness, we hypothesize this is related to degree gravitational reworking cover has undergone is therefore proxy for maturity surface debris covers. In cases tested here, using single value instead accounting observed thickness variability underestimates modelled midsummer sub-debris ablation rates by 11 %–30 %. While no simple relationship found between measured debris morphometric terrain parameters, analysis GPR data in conjunction with high-resolution models provides some insight into processes reworking. Periodic sliding failure of debris, rather than progressive mass diffusion, appears be main process redistributing debris. The incidence is controlled by slope, aspect, upstream catchment area via their impacts predisposition slope failure meltwater availability at debris–ice interface. Slope stability modelling the percentage debris-covered glacier subject debris instability can considerable at scale, indicating up to 32 % susceptible developing ablation hotspots associated patches thinner