Impacts of lateral conductive heat flow on ground temperature and implications for permafrost modeling.

Permafrost ground temperature and its spatial distribution are usually calculated using one-dimensional models based on heat flow in the vertical direction. Here, we theoretically calculated the impacts of lateral conductive heat flow on ground temperature under equilibrium and transient conditions. The results show that lateral heat flow has strong impacts on ground temperature, especially in deep ground. The different patterns of ground temperature with depth observed at 191 boreholes in a small mining area in northeastern Canada can generally be explained by the effects of lateral heat flow. Lateral effects are widespread in permafrost regions due to the large spatial variation in near surface ground temperature. Our analysis shows that one-dimensional permafrost models may have errors of 5 °C when the size of the grid cell is small. We estimated the horizontal extents and depths of the effects of lateral heat flow under typical conditions. These results can be used as a guide for modeling and mapping permafrost and selecting observation sites in the field.