Glacier geometry and flow speed determine how Arctic marine-terminating glaciers respond to lubricated beds

Abstract

Abstract. Basal conditions directly control the glacier sliding rate and the dynamic discharge of ice. Recent glacier destabilization events indicate that some marine-terminating glaciers quickly respond to lubricated beds with increased flow speed, but the underlying physics, especially how this vulnerability relates to glacier geometry and flow characteristics, remains unclear. This paper presents a 1D physical framework for glacier dynamic vulnerability assuming sudden basal lubrication as an initial perturbation. In this new model, two quantities determine the scale and the areal extent of the subsequent thinning and acceleration after the bed is lubricated: Péclet number (Pe) and the product of glacier speed and thickness gradient (dubbed J0 in this study). To validate the model, this paper calculates Pe and J0 using multi-sourced data from 1996 to 1998 for outlet glaciers in the Greenland ice sheet and Austfonna ice cap, Svalbard, and compares the results with the glacier speed change during 1996/1998–2018. Glaciers with lower Pe and J0 are more likely to accelerate during this 20-year span than those with higher Pe and J0, which matches the model prediction. A combined factor of ice thickness, surface slope, and initial flow speed physically determines how much and how fast glaciers respond to lubricated beds in terms of speed, elevation, and terminus change.

Glacier geometry limits the propagation of thinning in Patagonian Icefields

“…), and the diffusion coefficient D0, of the diffusive-kinematic wave is expressed by the Péclet number (𝑃𝑒) (Felikson et al, 2017;Zheng et al, 2019;Felikson et al, 2021;Zheng, 2022). In these coefficients, 𝐶 !…”

“…The geometric state of ice flow has the potential to define regions of upstream stability so that, depending on the location of these limits, the degree of vulnerability of a glacier to thinning could be deduced (Felikson et al, 2017(Felikson et al, , 2021Zheng, 2022). These discoveries, based on the model of diffusive kinematic waves (Nye, 1963(Nye, , 1960Weertman and Birchfield, 1983), have used the Péclet number as a metric to define these regions (Felikson et al, 2017(Felikson et al, , 2021.…”

“…These discoveries, based on the model of diffusive kinematic waves (Nye, 1963(Nye, , 1960Weertman and Birchfield, 1983), have used the Péclet number as a metric to define these regions (Felikson et al, 2017(Felikson et al, , 2021. The Péclet number corresponds to the relationship between advection and diffusion of the kinematic wave equation in glaciers ( Felikson et al, 2017;Zheng et al, 2019;Felikson et al, 2021;Zheng, 2022). Kinematic wave theory establishes that glacial thinning can be modeled as a wave propagating upstream due to a perturbation in the terminus.…”

“…To carry out this research, we used the Péclet number based on the diffusive kinematic wave model as a glacier vulnerability metric, widely used in Greenland glaciers (Felikson et al, 2017;Zheng et al, 2019;Felikson et al, 2021;Zheng, 2022). We analyzed the relationship between this geometric metric and the thinning, front changes, and force balance of the Patagonian Icefields glaciers over the last two decades.…”

GLAcier Feature Tracking testkit (GLAFT): A statistically- and physically-based framework for evaluating glacier velocity products derived from satellite image feature tracking

“…Accurate measurements of glacier surface velocity are fundamental to answering some of the most societally relevant issues in the cryospheric sciences. Glacier flow speeds underpin many projections of future sea level rise (Moon et al, 2012;Mouginot et al, 2019;Shepherd et al, 2020) and they are essential for models used to understand the processes that control ice sheet behavior -ice creep, basal sliding, and ice-ocean interactions (Holland et al, 2008;Burgess et al, 2013;Sundal et al, 2013;Zheng, 2022;. As a sensitive indicator of change, glacier velocities can be used to understand and monitor dangerous glacier surges and detachments (Evans et al, 2009;Shangguan et al, 2021;, and quantify freshwater storage volumes in regions reliant on glacier melt as a water resource (Millan et al, 2022;.…”