Abstract: The seasonal variations of psychological reactions in isolated and confined environments have been studied and theorized in terms of the third-quarter phenomenon; the third quarter of the isolation period is the moment when the most discomfort is reported by the winterers. Referring to Rivolier's comparative study, this article examines the manifestations of the third-quarter phenomenon by analyzing the data collected with an observation grid completed by the mission's doctor. The stress reactions of 27 winterers are observed during a 50-week period. The results show that the third-quarter phenomenon does not appear after the middle of the stay but more precisely after the middle of the isolation period. Changes in moods and personal reactions are reported but also in social and physical reactions. The results are discussed in terms of externalization of stress reactions and the influence of the data collection method emphasized.

Abstract: IUGG 2011 Melbourne Australia.

Abstract: The surface area of snow that is accessible to gases is an essential parameter for quantifying the exchange of trace gases between the snowpack and the atmosphere and is called the specific surface area (SSA). Snow SSA decreases during metamorphism, but this is not described in current snow models owing to the complexity of the physics and geometry of snow. In this paper, we test whether it is possible to model snow SSA changes during isothermal metamorphism without accounting for all the complexity of the three-dimensional (3-D) structure of real snow. We have developed a mean field model of snow metamorphism under isothermal conditions, grounded in the theoretical framework of transient Ostwald ripening and representing snow as a distribution of spherical particles. Analytical expressions of the growth rates of these spheres are obtained, and the evolution of two measurable parameters that characterize snow geometry, the SSA and the distribution of radii of curvature (DRC), are simulated and compared to experimental data obtained by X-ray tomography. The qualitative effects of temperature, snow density, and the condensation coefficient on the rate of SSA decrease are examined. The model predicts very well the rate of evolution of the particle size distribution, which validates our physical description of isothermal metamorphism. In particular, we find that vapor phase diffusion is rate limiting. However, the calculation of the SSA from the DRC appears delicate and evidences too crude approximations in our description of the 3-D geometry of snow. Finally, it is stressed that the initial DRC can greatly influence the rate of SSA decrease, while experimental measurements of the rate of SSA decrease suggest that all snow types evolve in a similar way. It is thus proposed that most natural fresh snows have similar DRCs.