An improved numerical model suggests potential differences of wind‐blown sand between on Earth and Mars

Abstract

The studies on wind‐blown sand are crucial for understanding the change of climate and landscape on Mars. However, the disadvantages of the saltation models may result in unreliable predictions. In this paper, the saltation model has been improved from two main aspects, the aerodynamic surface roughness and the lift‐off parameters. The aerodynamic surface roughness is expressed as function of particle size, wind strength, air density, and air dynamic viscosity. The lift‐off parameters are improved through including the dependence of restitution coefficient on incident parameters and the correlation between saltating speed and angle. The improved model proved to be capable of reproducing the observed data well in both stable stage and evolution process. The modeling of wind‐blown sand is promoted by all improved aspects, and the dependence of restitution coefficient on incident parameters could not be ignored. The constant restitution coefficient and uncorrelated lift‐off parameter distributions would lead to both the overestimation of the sand transport rate and apparent surface roughness and the delay of evolution process. The distribution of lift‐off speed and the evolution of lift‐off parameters on Mars are found to be different from those on Earth. This may thus suggest that it is inappropriate to predict the evolution of wind‐blown sand by using the lift‐off velocity obtained in steady state saltation. And it also may be problematic to predict the wind‐blown sand on Mars through applying the lift‐off velocity obtained upon terrestrial conditions directly.

The Physics of Sediment Transport Initiation, Cessation, and Entrainment Across Aeolian and Fluvial Environments

“…The findings from collision experiments with static beds are often applied to model fluvial bedload (Berzi et al, ; Pähtz, Liu, et al, ) and aeolian saltation transport (Andreotti, ; Berzi et al, , ; Bo et al, ; Claudin and Andreotti, ; Creyssels et al, ; Huang et al, ; Jenkins et al, ; Jenkins and Valance, , ; Kok, ; Kok and Renno, ; Lämmel et al, ; Lämmel and Kroy, ; Pähtz et al, ; Pähtz, Liu, et al, ; Wang and Zheng, , ). However, if the time between successive particle‐bed impacts is too short for a bed particle to fully recover from each impact, it can accumulate more and more kinetic energy with each impact.…”

A prediction method for the size distribution of saltating particles above a mixed‐size bed

“…It should be pointed out that due to the limitation of experimental methods, the distribution of α and β cannot be obtained through experiments. Studies by Zheng et al (2005), Zheng et al (2013) and Bo et al (2017) show that when α and β are taken as uniform distributions, the predicted lift‐off velocity distribution and transport rate are close to the field observation, which indicates that the uniform distribution may be approximately used for the distribution of α and β . Therefore, the form of uniform distribution was still adopted in the research of this article.…”

Comparisons suggest more efforts are required to parameterize wind flow around shrub vegetation elements for predicting aeolian flux

“…The lateral cover λ ranges from 0.03125 to 0.125. The mean diameter of soil particles is assumed to be 0.25 mm and the impact threshold u *it is taken as 0.2 m/s 3,31 . Because of the randomness and complexity of soil surface, the fluid threshold for PM10 is taken as 0.3 m/s 29,32 .…”