Modeling Dry-Snow Densification without Abrupt Transition

• Published in: Geosciences
• Main Author: Elizabeth Morris
• Format: Article in Journal/Newspaper
• Language: English
• Published: MDPI AG 2018
• Subjects: snow models; densification; Geology; QE1-996.5; Pine Island Glacier; Langway; Antarc*; Antarctica; Pine Island
• Online Access: https://doi.org/10.3390/geosciences8120464; https://doaj.org/article/f84ece3c8cb54d20b4b9a9677a9e6416

An empirical model for the densification of dry snow has been calibrated using strain-rate data from Pine Island Glacier basin, Antarctica. The model provides for a smooth transition between Stage 1 and Stage 2 densification, and leads to an analytical expression for density as a function of depth. It introduces two new parameters with a simple physical basis: transition density <math display="inline"> <semantics> <msub> <mi>ρ</mi> <mi>T</mi> </msub> </semantics> </math> and a scaling factor, M, which controls the extent of the transition zone. The standard (Herron and Langway) parameterization is used for strain rates away from the transition zone. Calibration, though tentative, produces best parameter values of <math display="inline"> <semantics> <msub> <mi>ρ</mi> <mi>T</mi> </msub> </semantics> </math> = 580 kg m <math display="inline"> <semantics> <msup> <mrow></mrow> <mrow> <mo>−</mo> <mn>3</mn> </mrow> </msup> </semantics> </math> and M = 7 for the region. Using these values, the transition model produces better simulations of snow profiles from Pine Island Glacier basin than the well-established Herron and Langway and Ligtenberg models, both of which postulate abrupt transition. Simulation of density profiles from other sites using M = 7 produces the best values of <math display="inline"> <semantics> <msub> <mi>ρ</mi> <mi>T</mi> </msub> </semantics> </math> = 550 kg m <math display="inline"> <semantics> <msup> <mrow></mrow> <mrow> <mo>−</mo> <mn>3</mn> </mrow> </msup> </semantics> </math> for a high accumulation site and 530 kg m <math display="inline"> <semantics> <msup> <mrow></mrow> <mrow> <mo>−</mo> ...