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Theses

Evolution de la surface spécifique de la neige. Etudes expérimentales et de terrain, paramétrisation.

Abstract : Dry snow is an air-ice mixture that is subjected to thermal gradients causing water vapour fluxes throughout the entire snowpack. They result in physical transformations in snow crystal size and shape and can entrain and release chemical species to the atmosphere. These phenomena are regrouped under the term “snow metamorphism”. They can lead to major modifications in physical variables of the snowpack and in the chemical composition of the atmosphere.
To better understand the influence of the metamorphism intensity on snow/air exchanges, we have performed laboratory studies, successively under isothermal and temperature gradient conditions, and field studies during a whole winter in Alaska. Snowpack physical properties were monitored, especially the snow specific surface area that is a central parameter in snowpack studies.
We have demonstrated that the rate of decay of the specific surface area of snow, both under isothermal and temperature gradient conditions, follows a simple logarithmic law. We have also showed that under isothermal conditions, this relationship is inferred from the general law of Ostwald ripening. Under non-isothermal conditions, the physics of the phenomena involved is more complex. We have then proposed an empirical description of the evolution of the specific surface area in order to take it into account in models of snowpack evolution. This study has also allowed us to identify crucial interactions between snow and climate.
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https://tel.archives-ouvertes.fr/tel-00012078
Contributor : Anne-Sophie Taillandier <>
Submitted on : Monday, April 3, 2006 - 9:28:52 PM
Last modification on : Thursday, November 19, 2020 - 3:54:26 PM
Long-term archiving on: : Saturday, April 3, 2010 - 9:25:09 PM

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  • HAL Id : tel-00012078, version 1

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Anne-Sophie Taillandier. Evolution de la surface spécifique de la neige. Etudes expérimentales et de terrain, paramétrisation.. Climatologie. Université Joseph-Fourier - Grenoble I, 2006. Français. ⟨tel-00012078⟩

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