Interpretation of the Meteorological Gale Environment through Mars Science Laboratory (MSL) Rover Environmental Monitoring Station (REMS) Observations and Mesoscale Modeling (MRAMS)

Abstract:

Gale Crater, in which the Mars Science Laboratory (MSL) landed in August 2012, is the most topographically complex area visited to date on Mars. The meteorology within the crater may also be one of the most dynamically complex meteorological environments, because topography is thought to strongly drive the near-surface atmospheric circulations. The Rover Environmental Monitoring Station (REMS) on the Curiosity rover consists of a suite of meteorological instruments that measure pressure, temperature (air and ground), wind (speed and direction), relative humidity, and the UV flux. REMS has provided some clues on the nature of the local meteorology strongly influenced by the complex topography, as predicted by numerous previous studies. As with all single station measurements, the meteorological interpretation is typically hindered by a lack of spatial context in which to place the observations. Numerical modeling results, when properly validated against observations, can provide interpretive context. In an effort to better understand the atmospheric circulations of the Gale Crater, the Mars Regional Atmospheric Modeling System (MRAMS) was applied to the landing site region using nested grids with a spacing of 330 meters on the innermost grid that is centered over the landing site. MRAMS is ideally suited for this investigation; the model is explicitly designed to simulate Mars’ atmospheric circulations at the mesoscale and smaller with realistic, high resolution surface properties. Simulations with MRAMS indicate thermal and wind thermal signatures associated with slope flows, katabatic winds, and nocturnal mixing events that are consistent with the rover environment monitored by REMS. Of particular note is evidence for two distinct air masses—one in the bottom of the crater (a relatively cold potential temperature air mass) and one on the plateau—that have minimal interaction with one another. If there are indeed two distinct air masses, there are strong implications for dust and water vapor cycling within Gale Crater. The air within Gale should be drier and less dusty due to limited mixing with the environment and limited dust lifting due to dust devils. Observations indicate a meteorological scenario that varies seasonally, and is far more complex than any previously measured surface environment.