High-fidelity subsurface thermal model as part of a Martian atmospheric column model

As the Martian atmosphere is observed in ever greater detail, more realistic computer models are required to interpret these measurements. Physical exchange processes between the atmosphere's lower boundary and the surface are often simplified. This is because the atmospheric calculations can describe the behaviour of the atmosphere accurately in many cases and simplifying the boundaries saves computing resources. However, the vertical heterogeneity of the subsurface (such as the presence of dust and ice layers) will interact via heat and mass transfer with the atmosphere. Here a new realistic numerical thermal conductivity scheme is introduced for use with a 1-D atmospheric column model useful for investigating the subsurface for layered material and to provide more accurate modelling of the Martian atmosphere. The model with the updated scheme produces results that are identical to the previous versions of the model in identical (non-layered) conditions. The updated model fits well to Viking 1 temperature data from the atmosphere using realistic thermal parameters. Introducing layered material, with different thermal properties, produces noticeable changes in the maximum and diurnal temperatures when changing the thickness of its top layer. The time of maximum surface temperature is only significantly changed when the thickness of the top layer is a moderate fraction of the top layer's skin depth.