Englacial hydrological characteristics of a typical continental-type glacier in China as detected by ground-penetrating radar

摘要

The englacial structures and ice thickness of the Laohugou No. 12 (L12) Glacier in the Qilian Mountains, China, were retrieved from ground-penetrating radar (GPR) profile data acquired in August of 2007. Here the interpretation of a typical GPR image is validated using two-dimensional, Finite-Difference Time-Domain (FDTD) numerical modeling. Data analyses revealed many englacial characteristics, such as temperate ice, crevasses, and cavities at the position of convergence between the eastern and western glacial branches of L12, and at an altitude between 4,600 and 4,750 m a.s.l. on the east branch. Combining ice thickness, englacial structures, subglacial topography, and surface flow velocities of this glacier, we analyzed the reasons for the distribution of temperate ice. The results show that greater englacial water content is associated with englacial crevassing and surface moulins, which allow water to be channeled to the temperate ice aquifer beneath the surface cold ice layer. Analysis of air temperature data shows that as more meltwater imports into the ice body, this has a great effect on water conservation and dynamics conditions. With climate warming, and under the influence of crevasses, subglacial structures, and ice thickness, ice thickness reduction on the L12 east branch is more rapid than that on the west branch.