Modelling the transition from grain-boundary sliding to power-law creep in dry snow densification

• Published in: Journal of Glaciology
• Main Authors: Elizabeth M. Morris, Lynn N. Montgomery, Robert Mulvaney
• Format: Article in Journal/Newspaper
• Language: English
• Published: Cambridge University Press 2022
• Subjects: Ice core; polar firn; snow physics; Environmental sciences; GE1-350; Meteorology. Climatology; QC851-999; Langway; ice core; Journal of Glaciology
• Online Access: https://doi.org/10.1017/jog.2021.95; https://doaj.org/article/dbee26ba302242f6b1a9248d1f2cc23a

This paper presents a physics-based macroscale model for the densification of dry snow which provides for a smooth transition between densification by grain-boundary sliding (stage 1) and densification by power-law creep (stage 2). The model uses established values of the stage 1 and 2 densification rates away from the transition zone and two transition parameters with a simple physical basis: the transition density and the half-width of the transition zone. It has been calibrated using density profiles from the SUMup database and physically based expressions for the transition parameters have been derived. The transition model produces better predictions of the depth of the nominal bubble close-off horizon than the Herron and Langway model, both in its classical form and in a recent version with re-optimised densification rates.