Time Dependent Model for Water Vapor Diffusion/adsorption and Heat Transfer at the Phoenix Landing

Introduction: Phoenix has shown that there exists vapor pressure variations on a diurnal time scale, which are not predicted by the GCM [1]. Recorded vapor pressures by the TECP shows systematic variations by about 2 orders of magnitude (Fig. 1) [2]. Since the GCM model does not take into account atmospheric interactions with the regolith, we may infer that the shortcomings of this model in this polar region implies that such interactions are significant [2]. Possible processes that may account for such a coupling include adsorption onto regolith grains as well as hydration of perchlorate [2] or equilibrium with a liquid phase [3]. We investigate the effect of adsorption as a potential sink for water vapor [4,5]. We are creating an integrated numerical model that accounts for both heat and mass transfer of water vapor in the regolith, including the effect of adsorption [4]. Using this model, we can simulate the effect of adsorption on humidity and attempt to relate this to Phoenix observations.