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摘要
High-resolution ice flow modeling requires bedrock elevation and ice thickness data, consistent with one another and with modeled physics. Previous studies have shown that gridded ice thickness products that rely on standard interpolation techniques (such as Bedmap2) can be inconsistent with the conservation of mass, given observed velocity, surface elevation change, and surface mass balance, for example, near the grounding line of Pine Island Glacier, West Antarctica. Using the BISICLES ice flow model, we compare results of simulations using both Bedmap2 bedrock and thickness data, and a new interpolation method that respects mass conservation. We find that simulations using the new geometry result in higher sea level contribution than Bedmap2 and reveal decadal-scale trends in the ice stream dynamics. We test the impact of several sliding laws and find that it is at least as important to accurately represent the bedrock and initial ice thickness as the choice of sliding law.
Plain Language Summary Models of fast-flowing outlet glaciers from ice sheets (known as ice streams) require numerous input data, including bedrock topography and ice thickness. Traditionally, these geometry data are produced from geostatistical interpolation of airborne radar measurements. However, these data products (e.g., Bedmap2) can result in unrealistic signals in model results. For example, near the grounding line of Pine Island Glacier, a major ice stream in West Antarctica, Bedmap2 has a region of shallow bedrock topography that, given velocity observations, produces spurious ice thickening, which is not observed in accumulation rates or surface elevation change. Therefore, the aim of this work is to produce and test a new mass-conserved geometry product of Pine Island Glacier. We use an ice flow model to compare geometries and find that simulations using the new geometry produces more sea level rise than Bedmap2, even when accounting for uncertainty in a parameter associated with ice sliding over bedrock. Model projections of future sea level rise from ice sheets depend on highly resolved and accurate geometry data products.
- 出版日期2018-4-16
