Motion of dust particles in dry snow under temperature gradient metamorphism

Pascal Hagenmuller (1) , Frederic Flin (1) , Marie Dumont (1) , François Tuzet (1) , Isabel Peinke (1) , Philippe Lapalus (1) , Anne Dufour (1) , Jacques Roulle (1) , Laurent Pézard (1) , Didier Voisin (2) , Edward Andò (3) , Sabine Rolland Du Roscoat (3) , Pascal Charrier (3)

1 CEN - Centre d'Etudes de la Neige
2 IGE - Institut des Géosciences de l’Environnement
3 3SR - Laboratoire sols, solides, structures - risques [Grenoble]

Abstract. The deposition of light-absorbing particles (LAPs) such as mineral dust and black carbon on snow is responsible for a highly effective climate forcing, through darkening of the snow surface and associated feedbacks. The interplay between post-depositional snow transformation (metamorphism) and the dynamics of LAPs in snow remains largely unknown. We obtained time series of X-ray tomography images of dust-contaminated samples undergoing dry snow metamorphism at around −2 ∘C. They provide the first observational evidence that temperature gradient metamorphism induces dust particle motion in snow, while no movement is observed under isothermal conditions. Under temperature gradient metamorphism, dust particles can enter the ice matrix due to sublimation–condensation processes and spread down mainly by falling into the pore space. Overall, such motions might reduce the radiative impact of dust in snow, in particular in arctic regions where temperature gradient metamorphism prevails.

Domains: Sciences of the Universe [physics]; Earth Sciences

Pascal Hagenmuller, Frederic Flin, Marie Dumont, François Tuzet, Isabel Peinke, et al.. Motion of dust particles in dry snow under temperature gradient metamorphism. The Cryosphere, 2019, 13 (9), pp.2345-2359. ⟨10.5194/tc-13-2345-2019⟩. ⟨meteo-03657903⟩