Salt polygons and porous media convection

TL;DR

This paper investigates the formation of salt polygons in arid regions, demonstrating they result from buoyancy-driven convection in porous soil through field data, experiments, and simulations.

Contribution

It provides a comprehensive analysis combining field observations, experiments, and simulations to explain the origin and size of salt polygons.

Findings

Salt polygons are caused by buoyancy-driven convection in porous soil.

The characteristic size of salt polygons depends on specific environmental conditions.

The study offers predictive insights into salt polygon formation in arid landscapes.

Abstract

From fairy circles to patterned ground and columnar joints, natural patterns spontaneously appear in many complex geophysical settings. Here, we investigate the origins of polygonally patterned crusts of salt playa and salt pans. These beautifully regular features, approximately a meter in diameter, are found worldwide and are fundamentally important to the transport of salt and dust in arid regions. We show that they are consistent with the surface expression of buoyancy-driven convection in the porous soil beneath a salt crust. By combining quantitative results from direct field observations, analogue experiments and numerical simulations, we further determine the conditions under which salt polygons should form, as well as how their characteristic size emerges.