soil transport by winds on Mars

TLDR

Eolian transport on Mars is inferred from low‑pressure wind tunnel experiments and theory, with saltation path lengths and ripple wavelengths varying by up to a factor of two with temperature, and particles moving faster and at lower angles than on Earth. The study develops a semi‑empirical relation to estimate the total mass of surface material transported by saltation, suspension, and traction. The model assumes a flat surface of nearly uniform‑size particles. The derived expression predicts a mass flux q = 2.61 ρ(V* – V*t)(V* + V*t)²/g, shows that larger mean particle size raises the threshold friction speed, and that the final particle velocity to threshold ratio is several times greater on Mars than on Earth.

Abstract

The eolian transport of surface material on the planet Mars is estimated from results of low‐pressure wind tunnel testing and theoretical considerations. A semiempirical relation is developed that will estimate the total amount of surface material moving in eolian saltation, suspension, and surface traction. The estimated total mass movement of surface material per unit width time on the surface of Mars is q = 2.61ρ( V * ‐ V *t )( V * + V *t ) 2 /g (g/cm s), where ρ is the density of the atmospheric gas, g is the acceleration due to gravity, and V * and V *t are the friction speed and saltation threshold friction speed, respectively. A flat surface composed of particles of nearly uniform size is assumed. A change in the mean particle size changes the threshold friction speed V *t . The path lengths of saltating particles and wavelengths of surface ripples can vary as much as a factor of 2 if the surface temperature varies from 150 to 250 K. The angles between particle paths and the horizontal surface are calculated to be lower on Mars than on earth, and particles travel much faster on Mars than on earth. The ratio of final particle velocity to threshold friction speed, V F /V *t , is found to be several times that of saltation on earth.