Subglacial hydrology as a control on emergence, scale, and spacing of ice streams

TL;DR

This paper investigates how subglacial hydrology influences the formation, spacing, and scale of ice streams through a coupled ice flow and meltwater model, revealing a natural length scale governing ice stream patterns.

Contribution

It introduces a coupled model analyzing ice stream properties, highlighting a fundamental length scale determined by hydrological and ice flow interactions, and explores effects of bed topography perturbations.

Findings

Identifies a natural length scale for ice stream separation and width.

Shows bed topography perturbations influence ice stream emergence.

Demonstrates evolution of ice streams towards the natural length scale.

Abstract

Observations have long associated ice streams with the presence of meltwater at the bed. More recently, theoretical models have been able to reproduce ice-stream behaviour as a consequence of the coupled dynamics of ice and subglacial meltwater. In this paper we analyse the properties of ice streams that form in a coupled model of ice flow and subglacial hydrology. We see that there is a natural length scale defining ice stream separation and width. This arises as a result of the balance between effective pressure gradients driving meltwater away from ice streams and the enhanced water production in the streams due to the fast ice flow. We further discuss how the model interacts with topography and we show that small perturbations to a uniform bed have a strong effect on where ice streams emerge in the model. However, in many cases ice streams then evolve to be closer to the dimensions defined by the natural length scale of the unperturbed system. The non-dimensional parameter that defines this length scale is therefore of fundamental importance in the model.