Transformation process observations of polar firn to ice 

Annals of Glaciology, Vol. 18, p. 199-202, 1993 

C.C. Langway, Jr.
Ice Core Laboratory, State University of New York at Buffalo, Buffalo, NY 14260, USA.
H. Shoji and A. Mitani
Snow and Ice Laboratory, Department of Earth Sciences, Toyama University, Toyama 930, Japan.
H.B. Clausen
Geofysisk Afdeling, Niels Bohr Instituttet for Astronomi, Fysik og Geofysik, Københavns Universitet

The transformation of snow to ice under compressive stress is a very slow process unless meltwater is present. A qualitative measure of permeability variation with depth was continuously determined for various shallow-ice cores from the dry-snow zones in both Greenland and Antarctica to investigate this transformation process. Results of the study provide insight into snow densification mechanisms and generally characterize the pore close-off phenomena. Measurements show that bulk densities may be expressed as a function of overburden; pore close-off takes place when the overburden is approximately 3.0-4.5 bar.