Meteorology of Candidate Mars Exploration Rover Landing Sites as Predicted by a Mesoscale Model

The meteorology of the Mars Exploration Rover (MER) candidate landing sites is of importance because of the constraint it provides on the likely ability of the rovers to successfully land and operate. The meteorology may also be of interest insofar as the landscapes to be traversed and studied by the rovers may be influenced to a greater or lesser degree by aeolian activity. In support of the MER Program, we have conducted studies of several of the candidate landing sites using the Mars Mesoscale Model developed at Caltech and Cornell University as an adaptation of the terrestrial PSU/NCAR Mesoscale Model (MM5). The sites studied include Meridiani (``Hematite"), Gusev, and Mellas. The model results suggest that winds associated with convection and/or topography may be of concern at each of the landing sites. The relatively flat Hematite site is simulated to develop strong, deep convection. At highest resolution (few hundred meters), the convection is predicted to be cellular with significant up- and down-drafts. The local time of landing for both MER rovers is during the period of most active convection at all sites. Gusev and Mellas show varying degrees of topographic influence on winds. At Gusev, the crater walls provide strong foci for upslope-downslope circulations, while the walls and other nearby topography provide ``anchor" points for the initiation (initial upwelling) of convection during the day. Mellas provides a case example of strongly channelized flow. Convection is less of a concern at Mellas, but is replaced by diurnally reversing up-canyon and down-canyon flow. The flow patterns are also strongly influenced by the effects of canyon wall heating by solar radiation. In summary, the thin Martian atmosphere responds strongly to slope heating by developing slope winds which provide a challenge to missions seeking to closely approach ``interesting" terrain. Equally a problem for the MER mission, for flat landing sites, is the use of an early afternoon local time of landing, coinciding with the peak of boundary layer convection.