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Article Dans Une Revue Boundary - Layer Meterology Année : 2004

Sensitivity Tests with a One-Dimensional Boundary-Layer Mars Model

Résumé

We present a series of sensitivity studies conducted using a one-dimensional Mars model (hereafter 1D model) of the University of Helsinki (UH). The reference case was the Pathfinder simulation for the second Martian day. Pathfinder temperatures and new wind speed observations from near the surface were available for validation. The Monin–Obukhov similarity parametrization for surface-layer turbulence was tested with various forms for the stability functions, and compared with the Pathfinder observations. The Dyer–Businger (DB) forms proved appropriate in the highly turbulent daytime Martian boundary layer. An iterative surface-layer treatment was introduced; this did not significantly change the results but showed that the Obukhov length L was about –30 m during daytime and +%5 m during nighttime. The importance of including water vapour and dust in the radiative transfer was tested in the Pathfinder simulations. Water vapour seems to have a significant effect, especially on the nighttime surface temperatures, by increasing the downwelling longwave radiation. Dust acts similarly and has an even greater longwave effect. It also extinguishes solar radiation strongly, thereby damping the surface temperature cycle. The sensitivity of the diurnal surface temperature variation on various physical properties of the soil (regolith) was studied. Thermal inertia and thermal conductivity had the largest effects. The Beagle 2 Lander of the European Space Agency (ESA) landed unsuccessfully on Mars at the end of the year 2003. The selected landing site was in the Northern Hemisphere tropics where seasonal variations are small, and the landing time corresponded roughly to early spring (Ls = 330°). The expected weather conditions at the site were simulated for four approximate Martian lsquomonthsrsquo consisting of 60 Martian solar days each. The driving conditions for the simulations were taken from the Mars climate database.

Dates et versions

hal-00561947 , version 1 (02-02-2011)

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Citer

Anni Määttänen, Hannu Savijrvi. Sensitivity Tests with a One-Dimensional Boundary-Layer Mars Model. Boundary - Layer Meterology, 2004, 113 (3), pp.305-320. ⟨10.1007/s10546-004-5274-y⟩. ⟨hal-00561947⟩
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