Thermodynamic simulation of the seasonal cycle of temperature, pressure and ice caps on Mars

Abstract

We present a thermodynamic model to simulate the atmospheric temperature and pressure, the regolith temperature and the polar CO 2 ice caps vertical thickness and horizontal extent of Mars. This is done using the temperatures of the atmosphere and regolith for each Martian day of the year, determined from the thermodynamic equation. Assuming a CO 2 atmosphere, we calculate its emission spectrum using the spectral calculator E-Trans with the HITRAN database (E-Trans/HITRAN), resulting in only a band at 15 mm and the rest transparent, through which the radiation emitted by the regolith and ice caps (considered as black bodies) goes toward space. We also include the solar radiation extinction and longwave emission of atmospheric dust. The equation calculates the energy balance between the absorbed solar radiation and the outgoing longwave radiation, incorporating also the latent heat released by CO 2 condensation, the sensible heat flux from the surface to the atmosphere, the latent heat flux due to the CO 2 ice sublimation and the heat exchange between the surface regolith layer and its lower layers. The atmospheric planetary scale horizontal turbulent heat transport is parameterized with an exchange coefficient, which is an order of magnitude smaller than that employed in the terrestrial troposphere. Considering a long-time average, the regolith vertical temperature profile is explicitly found using the thermal inertia including conductivity; its temperature regulation is achieved through the thermal conduction from the surface during the warm season. This stored energy goes back to the surface during the cold season. Our model simulates the seasonal variation of the polar ice caps and consequently of the surface atmospheric pressure through the CO 2 mass balance between them. Finally, it is explicitly shown that the amplitude of the global seasonal pressure cycle is modulated by a local thermal-orographic effect, which increases (decreases) this amplitude in the low (high) regions, which agrees with the observations of the Viking Landers 1 and 2, and the Mars Climate Data Base. Our prediction for Hellas Planitia gives an amplification factor of up to 2.15, coinciding with other authors.

Modelling the Present Global Terrestrial Climatic Response Due to a Chicxulub-Type Asteroid Impact

“…In the experiments reported here, we use the Thermodynamic Climate Model (TCM), described in detail in previous works [23,24]. It is an energy balance model consisting of an atmospheric layer of about 11 km thickness, an oceanic mixed layer 60 m in depth and a continental layer of negligible depth.…”

“…The snow-ice feedback discussed in [24] is incorporated by the snow accumulation that forms the polar cap, which is determined by the radiative cooling of the atmosphere and surface (as with nightly freezing) due to the stratospheric aerosols.…”

“…We further consider the ocean and continent heat exchange with the subsurface, a process through which, in successive layers, the internal energy is stored by heat transfer during daylight and released during the long "night", also produced by the stratospheric aerosols in a process similar to that of the winter night on Mars [24].…”