Abstract
AbstractHigh‐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.
Highlights
Previous studies have shown that gridded ice thickness products that rely on standard interpolation techniques 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
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
Numerical models of marine ice streams—that is, ice streams flowing over bedrock lying well below sea level such as the major glaciers of West Antarctica—are accurate if they can properly represent the dynamics of the region around the grounding line
Summary
Numerical models of marine ice streams—that is, ice streams flowing over bedrock lying well below sea level such as the major glaciers of West Antarctica—are accurate if they can properly represent the dynamics of the region around the grounding line. For Pine Island Glacier, a fast-flowing ice stream in the Amundsen Sea Embayment, West Antarctica, Bedmap, along with velocity observations, produces a thickening tendency of order 100 m yr−1 in the region of the grounding line, which is not observed in the pattern of dh∕dt or SMB (Rignot et al, 2014). We model the Pine Island Glacier catchment using two different bed geometries: Bedmap and a geometry created using the principle of mass conservation, that is, a mass-conserving initial thickness and bedrock along the lines of Millan et al (2017), Morlighem et al (2011), and Rignot et al (2014). We aim to demonstrate the importance of having a consistent representation of the bed, in the vicinity of the grounding line, to modeling short-term ice stream dynamics
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