Polar Firn Densification and Grain Growth

Impurity-controlled densification: a new model for stratified polar firn

A new densification model, which simulates the effect of impurities on the densification of polar firn, is presented. The classical densification models of Herron and Langway (1980) and Pimienta and Barnola (Barnola and others, 1991) are modified by assuming that the activation energy for deformation is reduced by the impurities. Motivated by recent observations, the impurity effect is formulat...

Firn Densification by Grain-boundary Sliding : a First Model

Densification in highly porous, isothermal firn occurs primarily by Newtonian sliding on grain boundaries, but the coordination number increases with density and restricts further sliding. At a relative density of about 0.6 the coordination number approaches 6 and sliding ceases to be a primary mechanism of densification; the resulting decrease in densification rate causes the critical point in...

On the impact of impurities on the densification of polar firn

Atmospheric trends of the halon gases from polar firn air

Atmospheric trends of the halon gases from polar firn air C. E. Reeves, W. T. Sturges, G. A. Sturrock, K. Preston, D. E. Oram, J. Schwander, R. Mulvaney, J.-M. Barnola, and J. Chappellez School of Environmental Sciences, University of East Anglia, Norwich, NR4 7TJ, UK Physics Institute, University of Berne, Berne, Switzerland British Antarctic Survey, Natural Environment Research Council, Cambr...

Two-step flash sintering of ZnO: Fast densification with suppressed grain growth

Article history: Received 19 June 2017 Received in revised form 14 July 2017 Accepted 14 July 2017 Available online xxxx Two-step flash sintering (TSFS) was proposed as a new ceramic fabrication method to achieve fast densification with suppressed grain growth. Using ZnO as an examplar, ~96.5% of theoretical density was achieved using TSFS with a grain size of ~370 nm, representing a N3 times r...