Changes of soil water content and lateral flow exert large effects on soil thermal dynamics across Alaskan landscapes

<p>Both lateral surface and subsurface hydrological processes affect soil moisture dynamics, yet most land surface models (LSMs) only solve subsurface water movement vertically.  Here we use a 3-D ecosystem model (ECO3D; Liao et al., 2019) that considers both land surface and subsurface hydrologic processes to simulate soil moisture, which is then used to drive a 1-D vertical soil thermal model (TEM-STM; Zhuang et al., 2002) to simulate the soil moisture effects on soil thermal dynamics in central Alaska.  Our coupled model improves soil temperature estimates by 43.5% in comparison with observational data.  Soil moisture has little effect on soil temperature during the wet season (-1.5 %) and a substantial influence during the dry season (60%).  Spatially, water lateral flow has significant impacts on both soil moisture and soil temperature, causing model estimates for unfrozen/thawed areas in the transition season to increase by ~10% in the study area. Our results highlight the importance of considering dynamic soil moisture, as well as lateral flow effects, on soil thermal dynamics in permafrost regions.</p>