The KRC Thermal Model for Analysis of Mars Infrared Mapping [in Honor of PRC]

The KRC thermal model has been the basis for the determination of thermal inertia for all Mars missions except Phobos and MGS. It has evolved over a period of four decades and has been used for a variety of planet, satellite and comet problems, but has never been fully described.

Because surface temperatures are the primary goal, the model uses a one-layer atmosphere but does allow fractional condensation and global pressure variation. The program is designed to compute surface and subsurface temperatures for a global set of latitudes at a full set of seasons, with enough depth to capture the annual thermal wave, and to compute seasonal condensation mass. For historic

reasons (it originated in the era of kiloHz processors) the code has substantial optimization for speed. It allows sloped surfaces and two vertical zones of different materials. There are generalities that allow use with any

planet/satellite. All physical and orbital parameters can be modified, so that it can be used with any planet/satellite.

The code uses layer thickness increasing exponentially downward and time steps that increase by factors of two deeper into the subsurface where stability criteria are met. KRC now uses a one-layer energy-conserving Delta-Eddington atmosphere, which version has been used for analysis of THEMIS and MER Mini-TES results. A limitation is that surface properties are temperature-independent.

A ``one-point'' capability allows input of a set of points defined by season, latitude, hour and a few major physical parameters. The capability to model temperatures at the bottom of conical pits was added to study the potential volatile sublimation in freshly exposed trenches to be dug by the Phoenix mission.