Amplification of dust loading in Martian dust devils by self-shadowing

TL;DR

This paper investigates how self-shadowing in Martian dust devils can significantly amplify dust lifting, potentially explaining their sustained activity and high dust fluxes on Mars.

Contribution

It introduces the concept that self-shadowing enhances dust entrainment in Martian dust devils, supported by microgravity experiments and scaling analysis.

Findings

Mass ejection rates increase tenfold with shadowing in experiments

Self-shadowing can significantly amplify dust flux on Mars

Mechanism may explain dust devil sustainability on Mars

Abstract

Insolation of the Martian soil leads to a sub-surface overpressure due to thermal creep gas flow. This could support particle entrainment into the atmosphere. Short time shadowing e.g. by the traverse of a larger dust devil would enhance this effect. We find in microgravity experiments that mass ejection rates are increased by a factor of 10 for several seconds if a light source of 12.6 kW/$\rm m^2$ is turned off. Scaled to Mars this implies that self-shadowing of a partially opaque dust devil might lead to a strongly amplified flux of lifted material. We therefore suggest that self-shadowing might be a mechanism on Mars to increase the total dust loading of a dust devil and keep it self-sustained.