Three-phase numerical model for subsurface hydrology in permafrost-affected regions

S. Karra, S. L. Painter, P. C. Lichtner
2014 The Cryosphere Discussions  
Degradation of near-surface permafrost due to changes in the climate is expected to impact the hydrological, ecological and biogeochemical responses of the Arctic tundra. From a hydrological perspective, it is important to understand the movement of the various phases of water (gas, liquid and ice) during the freezing and thawing of near sur-5 face soils. We present a new non-isothermal, single-component (water), three-phase formulation that treats air as an inactive component. The new
more » ... t. The new formulation is implemented in the massively parallel subsurface flow and reactive transport code PFLO-TRAN. Parallel performance for this implementation is demonstrated, and validation studies using previously published experimental data are performed. A comparison 10 between the new model and a more complete two-component (air-water) multiphase approach shows only minor differences. When water vapor diffusion is considered, a large effect on soil moisture dynamics is seen, which is due to dependence of thermal conductivity on ice content. A large three-dimensional simulation (with around 6 million degrees of freedom) of seasonal freezing and thawing is also presented. 15 25
doi:10.5194/tcd-8-149-2014 fatcat:virmyl6zubfexigyl4cnzea4um