Full-Stokes modeling of a polar continental glacier: the dynamic characteristics response of the XD Glacier to ice thickness

摘要

The steady-state diagnostic and prognostic simulation for the Xiao Dongkemadi glacier (XD) of the Tibetan Plateau was performed with the thermo-mechanically-coupled-with-Full-Stokes code Elmer (http://www.csc.fi/elmer/). In this paper, some changes of glacial thermodynamic parameters caused by ice thickness and atmospheric temperature variation were simulated in view of different thickness. The purpose of this study was to fill the gap in analyzing the ice dynamic characteristic of a polar continental glacier. The diagnostic simulation revealed the following conclusions: (1) when the thickness change was small, surface velocity, ice temperature, and deviation stress variation in the bedrock showed a tendency to change with thickness, and when the terrain was gentle, the thickness variation dominated the ice velocity. (2) The ice temperature of the bedrock was high in the whole profile and reached the pressure melting point in the terminus, and it was easy to slide at the bottom, which was consistent with the measured ground penetrating radar data near the terminus. (3) The static friction forces decrease with thickness, and they showed a complex nonlinear relationship, which revealed that the deviation stress in the bottom was influenced by thickness and ice temperature at the bedrock. The prognostic simulating from 2007 to 2047 presented: (1) The simulation forecasted a shrinkage of nearly 600 m in the terminus and the longitudinal section, and wound up diminished by nearly 25% by the end of 2047; (2) the change of thickness was small at the region between 5650 and 5700 m.a.s.l, which might be related to lower atmospheric temperature; (3) thickness dominated the deviation stress (sigma(xx) and sigma(xz)) in the bottom, and the impact of the terrain was little higher compared to deviation stress (sigma(xx)). In other words, the glacial thickness dominated the glacial force and movement to a great extent and the low temperature at high altitude reduced the XD's sensi