METEOROLOGICAL PREDICTIONS FOR THE MARS PATHFINDER LANDER

The NASA Ames Mars general circulation and boundary layer models are u sed as guides to forecast the meteorological environment of the Pathfi nder lander site. Based on these models we predict that for a Viking-l ike atmospheric dust loading, significant vertical wave structure will be seen in the entry temperature profile above 50 km. Temperatures in this region will oscillate by up to 30 K about a mean value of simila r to 145 K. At the surface during the primary mission, winds are expec ted to rotate clockwise during the day at 2-10 m/s, while air temperat ures will range from overnight lows in the mid 180s K to daytime highs near 250 K. If the atmosphere is dust free at arrival, as appears pos sible from recent Earth-based observations, then we expect a cooler up per atmosphere (130-140 K) with less wave structure during entry, weak er surface winds, and a slight increase in near surface air temperatur es. Regardless of dust loading, we predict that the daily averaged sur face pressure will reach its annual minimum about 15-20 sols after lan ding. During the extended mission, the basic character of Pathfinder's meteorology will change from that of a summertime quasi-regular regim e to that of a wintertime highly variable regime. This transition is p redicted to occur by sol 60. The strongest winds (30 m/s) and lowest d aily-averaged temperatures (similar to 200 K) will be recorded during early winter.