Preprints
https://doi.org/10.5194/egusphere-2022-1310
https://doi.org/10.5194/egusphere-2022-1310
 
09 Jan 2023
09 Jan 2023
Status: this preprint is open for discussion.

Revisiting the role of vertical shear in analytic ice shelf models

Chris Miele1, Timothy C. Bartholomaus1, and Ellyn M. Enderlin2 Chris Miele et al.
  • 1Department of Geological Sciences, University of Idaho, Moscow, ID, USA
  • 2Department of Geosciences, Boise State University, Boise, ID, USA

Abstract. Analytic modeling of ice shelf flow began when Weertman derived an expression for the strain rates within an unconfined shelf, of uniform thickness, extending only in one direction. Nearly two decades later, Thomas generalized Weertman's analysis to ice shelves of nonuniform thickness, deriving one of the most well-known analytic models in glaciology: . However, despite the prevalence of this model in both historical and contemporary texts, there remain persistent miscommunications regarding the role of vertical shear in its construction. In Thomas' original approach, vertical shear stress was considered negligible in the stress balance; in a significant contrast, the same model is typically derived in contemporary texts by the neglect of basal resistance. These two approaches are not equivalent, and yet, it remains common to misinterpret vertical shear stress as typically neglected in current ice shelf modeling studies. This manuscript provides clarification on this pervasive misconception. We emphasize that vertical shear stress should not be interpreted as negligible in the construction of general shallow shelf models. However, we also demonstrate that the vertical shear stress inherent in Thomas' expression does not give rise to a well-defined vertical shear strain rate. For situations in which vertical shear stress in shallow ice shelf models is of interest, we provide guidance on how to best calculate it.

Chris Miele et al.

Status: open (until 10 Mar 2023)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2022-1310', Anonymous Referee #1, 26 Jan 2023 reply
    • AC1: 'Reply on RC1', Chris Miele, 27 Jan 2023 reply

Chris Miele et al.

Chris Miele et al.

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Short summary
Vertical shear stress (the stress orientation usually associated with vertical gradients in horizontal velocities) is a key component of the stress balance of ice shelves. However, partly due to historical assumptions, vertical shear is often misspoken of today as "negligible" in ice shelf models. We address this miscommunication, providing conceptual guidance regarding this often-misrepresented stress. Fundamentally, vertical shear is required to balance thickness gradients in ice shelves.