A new model to simulate the Martian mesoscale and microscale atmospheric circulation: Validation and first results

Abstract

[1] The Laboratoire de Météorologie Dynamique (LMD) Mesoscale Model is a new versatile simulator of the Martian atmosphere and environment at horizontal scales ranging from hundreds of kilometers to tens of meters. The model combines the National Centers for Environmental Prediction(NCEP)-National Center for Atmospheric Research (NCAR) fully compressible nonhydrostatic Advanced Research Weather Research and Forecasting (ARW-WRF) dynamical core, adapted to Mars, with the LMD-general circulation model (GCM) comprehensive set of physical parameterizations for the Martian dust, CO 2 , water, and photochemistry cycles. Since LMD-GCM large-scale simulations are also used to drive the mesoscale model at the boundaries of the chosen domain of interest, a high level of downscaling consistency is reached. To define the initial state and the atmosphere at the domain boundaries, a specific ''hybrid'' vertical interpolation from the coarse-resolution GCM fields to the high-resolution mesoscale domain is used to ensure the stability and the physical relevancy of the simulations. Used in synoptic-scale mode with a cyclic domain wrapped around the planet, the mesoscale model correctly replicates the main large-scale thermal structure and the zonally propagating waves. The model diagnostics of the nearsurface pressure, wind, and temperature daily cycles in Chryse Planitia are in accordance with the Viking and Pathfinder measurements. Afternoon gustiness at the respective landing sites is adequately accounted for on the condition that convective adjustment is turned off in the mesoscale simulations. On the rims of Valles Marineris, intense daytime anabatic ($30 m s À1 ) and nighttime katabatic ($40 m s À1 ) winds are predicted. Within the canyon corridors, topographical channeling can amplify the wind a few kilometers above the ground, especially during the night. Through large-eddy simulations in Gusev Crater, the model describes the mixing layer growth during the afternoon, and the associated dynamics: convective motions, overlying gravity waves, and dust devil-like vortices. Modeled temperature profiles are in satisfactory agreement with the Miniature Thermal Emission Spectrometer (Mini-TES) measurements. The ability of the model to transport tracers at regional scales is exemplified by the model's prediction for the altitude of the Tharsis topographical water ice clouds in the afternoon. Finally, a nighttime ''warm ring'' at the base of Olympus Mons is identified in the simulations, resulting from adiabatic warming by the intense downslope winds along the flanks of the volcano. The surface temperature enhancement reaches +20 K throughout the night. Such a phenomenon may have adversely affected the thermal inertia derivations in the region.

Structure and dynamics of the convective boundary layer on Mars as inferred from large‐eddy simulations and remote‐sensing measurements

“…The last phenomenon was the focus of the Toigo et al (2003) LES study which showed similarities between the modelled vortices and the observed Martian dust devils. These preliminary results were recently confirmed by other studies (Richardson et al, 2007;Sorbjan, 2007;Spiga and Forget, 2009). LESs were also used to investigate atmospheric hazards during the entry, descent and landing (EDL) of the Mars Exploration Rovers (MER) (Rafkin and Michaels, 2003;Toigo and Richardson, 2003) and the Phoenix lander (Michaels and Rafkin, 2008;Tyler et al, 2008).…”

“…For instance, Michaels and Rafkin (2004) found that the horizontal structures of updraughts simulated in LES and convective clouds observed by MOC were similar. Spiga and Forget (2009) noticed encouraging agreement between LES results in Gusev Crater and MER miniTES temperature profiles up to 2 km above the surface (Smith et al, 2006).…”

The Noise Model of the SEIS Seismometer of the InSight Mission to Mars

“…A pressure and wind field has been generated around the landing site thanks to a LES simulation as described in Spiga and Forget (2009). The resulting pressure noise tilt (vertical and horizontal) is estimated at two wind speeds by Sorrels method (see Fig.…”

“…In order to focus on the seismic bandwidth, we are interested in simulations of the pressure variations between 1 s and 100 s. This level of resolution of pressure field simulations is reached only by the Large Eddy Simulations (LES) that can resolve the turbulence-related phenomena at the interface between the Martian surface and the atmosphere, plus theoretical considerations for periods below 10 seconds. High resolution LES, as described in Spiga and Forget (2009) can use grids smaller than 50 m of resolution and can therefore simulate convective motions of the atmosphere as well as the large vortices and turbulent structures such as dust devils, which are expected to be the main source of turbulence related tilt noise in our bandwidth.…”

Dust Devil Sediment Transport: From Lab to Field to Global Impact

“…pressure drops of a few Pascals, sizes from a few tens to hundreds of meters, vertical extension of about a kilometer, and durations from a few tens to at most a few thousands of seconds (Rafkin et al 2001;Toigo and Richardson 2003;Michaels and Rafkin 2004;Spiga and Forget 2009;Gheynani and Taylor 2011). Those parameters are generally all larger for martian dust devils than for their terrestrial counterparts, which is consistent with the generally larger dust flux supposedly originating from Mars's dust devils compared to Earth's.…”