Characterization of the Martian Surface Layer

Abstract

The authors have estimated the diurnal evolution of Monin?Obukhov length, friction velocity, temperature scale, surface heat flux, eddy-transfer coefficients for momentum and heat, and turbulent viscous dissipation rate on the Martian surface layer for a complete sol belonging to the Pathfinder mission. All these magnitudes have been derived from in situ wind and temperature measurements at around 1.3-m height and simulated ground temperature (from 0600 sol 25 to 0600 sol 26). Previously, neither values of turbulent viscous dissipation rate and eddy-transfer coefficients from in situ measurements for the Martian surface layer nor diurnal evolutions of all the previously mentioned turbulent parameters for the Pathfinder had been obtained. Monin?Obukhov similarity theory for stratified surface layers has been applied to obtain the results. The values assigned to the surface roughness and the applied parameterization of the interfacial sublayer will be discussed in detail with respect to the results? sensitivity to them. The authors have found similarities concerning the order of magnitude and qualitative behavior of Monin?Obukhov length, friction velocity, and turbulent viscous dissipation rate on Earth and on Mars. However, quantities directly related to the lower Martian atmospheric density and thermal inertia, like temperature scale and hence surface heat flux, range over different orders of magnitude. Additionally, turbulent exchanges in the first few meters have been found to be just two orders of magnitude higher than the molecular ones, whereas on Earth around five orders of magnitude separate both mechanisms.