A model study of the atmospheric boundary layer in the Mars Pathfinder lander conditions

The diurnal cycle in the Mars Pathfinder sol 3-6 observed temperatures is c ompared with results from a one-dimensional high-resolution atmospheric bou ndary-layer model for Mars. The agreement is in general quite good, the mod el catching the observed cycle well with realistic regolith (soil) paramete r values. The model processes driving the temperature changes, such as the surface radiation and heat budgets, and the atmospheric radiative and turbu lent heating rates, are presented and discussed. The model includes moisture, and its hydrologic cycle is described. It indi cates a dryish soil and a quite dry daytime well-mixed boundary layer up to 5 km with specific-humidity values around 0.18 g kg(-1). The relative humi dity increases strongly in the evening and saturation is reached by 04 loca l time near the surface. The very thin radiation fog thus formed is dissolv ed soon after sunrise. There is weak frost formation at night and sublimati on during daytime.