Snow grain-size measurements in Antarctica

Michel Gay (1) , Michel Fily (1) , Massimo Frezzotti (2) , Christophe Genthon (1) , Hans Oerter (3) , J.-G. Winther (4)

1 LGGE - Laboratoire de glaciologie et géophysique de l'environnement
2 ENEA - Ente per le Nuove Tecnologie, l'Energia e l'Ambiente
3 Abteilung Klinische Sozialmedizin, Berufs- und Umweltdermatologie
4 Norwegian Polar Institute

Grain-size is an important but not well-known characteristic of snow at the surface of Antarctica. In the past, grain-size has been reported using various methods, the reliability, reproducibility and intercomparability of which is not warranted. In this paper, we present and recommend, depending on available logistical support, three tech- niques of snow-grain sampling and/or imaging in the field as well as an original digital image-processing method, which we have proved provides reproducible and intercompar- able measures of a snow grain-size parameter, the mean convex radius. Results from more than 500 samples and 3000 images of snow grains are presented, which yield a still spatially limited yet unprecedentedly wide picture of near-surface snow grain-size distribution from fieldwork in Antarctica. In particular, except at sites affected by a very particular meteor- ology, surface grains in the interior of the ice sheet are uniformly small (0.1^0.2 mm). The climate-related increase of grain-size with depth through metamorphism is, as expected, not spatially uniform. Our Antarctic snow grain-size database will continue to grow as field investigations bring new samples, images and measures of snow grain.

Domaines: Géophysique [physics.geo-ph]; Géophysique [physics.geo-ph]

Michel Gay, Michel Fily, Massimo Frezzotti, Christophe Genthon, Hans Oerter, et al.. Snow grain-size measurements in Antarctica. Journal of Glaciology, 2002, 48 (163), pp. 527-535. ⟨hal-00645916⟩