Mars Pathfinder: New data and new model simulations

摘要

The diurnal cycle in the temperature and wind speed of the Mars Pathfinder lander (MPF) is compared with the results from a one-dimensional high-solution boundary-layer model. The radiation scheme of the model has been validated against line-by-line calculations in an average Martian case. The agreement with MPF observations is good. Strong daytime turbulent variability and steep vertical temperature gradients characterize the observations. A detailed look at the model physics reveals thai the thin atmosphere responds strongly to thermal radiation. During the daytime, absorption of surface-emitted thermal radiation by CO_2. water vapour and dust is the main heating agent below 200 m despite the faet that the surface layer is sirongl) convcctive anddust absorbs solar radiation. The night-time inversion is also transferred to the air mainly by long-waxe processes, although turbulent eooling dominates very near the surface (below 40 m). The near-surface net healing/cooling displays a sensithe balancebetween several large and opposite physical processes, wherefore accurate algorithms and high resolution are needed for detailed model results. The modelled hydrologic cycle reveals a well-mixed layer of up to 5 km with thin icy fog and frost forming inthe night-time. These sublimate back to the air soon after sunrise.