The effect of organic soil layer on simulated permafrost dynamics

Abstract:

Soil organic layer controls energy exchange between the air and the ground in permafrost affected soils in the Northern Hemisphere. Organic soils contribute to an increase in soil moisture and provide a better insulation against summer heat. Better ground insulation is possible due to thermal conductivity of a thawed organic layer, which is about two times lower than thermal conductivity of a frozen organic layer. In this study, we implemented changing in time soil organic layer into the Simple Biosphere/Carnegie-Ames-Stanford Approach (SiBCASA) terrestrial ecosystem model to illustrate how the soil organic layer affects soil temperature dynamics and soil carbon dynamics. We used CRUNCEP reanalysis data to run the model for its equilibrium state with a stable climate. Our results indicate that the presence and dynamics of the organic layer allow us to better simulate active layer thickness. Moreover, dynamic carbon redistribution as a result of changing organic layer improves the simulated distribution of soil carbon with depth.