Effect of localized high basal melting on transient subglacial water flow evolution beneath Campbell Glacier, Antarctica

Abstract

Observing the flow of subglacial water evolution beneath the polar ice sheet has long been a challenging issue. The spatiotemporal subglacial water evolution can be indirectly estimated by ice-radar, GPS, and satellite altimetry technique. At present, one of the main causes of the accelerated migration of the Antarctic ice sheet is ice-bed boundary conditions in terms of subglacial hydrology. However, its reliability is low due to the limited observation and verification data. Based on the GPS time series along the Campbell Glacier, we observed that the ice sheet surface height (h) and ice sheet velocity (v) represent a specific periodicity. In terms of the subglacial hydrologic flow, these changes are caused by the sequential steps as follows: accumulation of melted water around subglacial lake ??increasing the water pressure ??increasing the ice sheet velocity due to the lower friction ??channel(efficient) flow activation ??rapid depletion of water storage ??the decrease of altitude and the reduction of ice sheet velocity. In this study, the GlaDS (Glacier Drainage System) model, which can realize interactions between sheet flow type and channel flow type, was used to realize the temporal and spatial hydrological variability beneath the Campbell glacier. The basal topography was constructed by recent ice radar (KOPRI/UTIG flight line) data with mass conservation(MC). Based on the assumption of high basal melting around active volcano Mt. Melbourne, with various channel and sheet hydraulic conductivity conditions, spatiotemporal subglacial flow evolution was analyzed. The localized high basal melting around Mt. Melbourne activates the high concentration of channelized flow, which modulate the effective pressure and subglacial discharge. The results showed that boundary conditions(e.g.. basal topography, basal melting distribution) beneath ice sheet should be better constrained to represent the flow close to reality.