On the Relationship between Dust Devil Radii and Heights

TL;DR

This paper investigates the relationship between dust devil radii and heights on Mars, proposing a model that predicts their proportionality and validating it with observational data from Mars Express.

Contribution

It introduces a simple model linking dust devil radii to heights based on angular momentum conservation, supported by observational data.

Findings

Radii scale with height to the power of 1/2

Model predictions align reasonably with observed data

Further surveys could refine understanding of dust devil dynamics

Abstract

The influence of dust devils on the martian atmosphere depends on their capacity to loft dust, which depends on their wind profiles and footprint on the martian surface, i.e., on their radii, $R$. Previous work suggests the wind profile depends on a devil's thermodynamic efficiency, which scales with its height, $h$. However, the precise mechanisms that set a dust devil's radius have remained unclear. Combining previous work with simple assumptions about angular momentum conservation in dust devils predicts that $R \propto h^{1/2}$, and a model fit to observed radii and heights from a survey of martian dust devils using the Mars Express High Resolution Stereo Camera agrees reasonably well with this prediction. Other observational tests involving additional, statistically robust dust devil surveys and field measurements may further elucidate these relationships.