What sets aeolian dune height?

• Published in: Nature communications Vol. 13; no. 1; pp. 2401 - 8
• Main Authors: Gunn, Andrew, Casasanta, Giampietro, Di Liberto, Luca, Falcini, Federico, Lancaster, Nicholas, Jerolmack, Douglas J.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 03.05.2022; Nature Publishing Group; Nature Portfolio
• Subjects: 704/106/35; 704/172; 704/445/215; Atmospheric boundary layer; Boundary layers; Dunes; Evolution; Geology; Growth rate; Humanities and Social Sciences; Landforms; multidisciplinary; Sand; Science; Science (multidisciplinary); Wavelengths; Wind; Wind effects
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-022-30031-1

Wherever a loose bed of sand is subject to sufficiently strong winds, aeolian dunes form at predictable wavelengths and growth rates. As dunes mature and coarsen, however, their growth trajectories become more idiosyncratic; nonlinear effects, sediment supply, wind variability and geologic constraints become increasingly relevant, resulting in complex and history-dependent dune amalgamations. Here we examine a fundamental question: do aeolian dunes stop growing and, if so, what determines their ultimate size? Earth’s major sand seas are populated by giant sand dunes, evolved over tens of thousands of years. We perform a global analysis of the topography of these giant dunes, and their associated atmospheric forcings and geologic constraints, and we perform numerical experiments to gain insight on temporal evolution of dune growth. We find no evidence of a previously proposed limit to dune size by atmospheric boundary layer height. Rather, our findings indicate that dunes may grow indefinitely in principle; but growth depends on morphology, slows with increasing size, and may ultimately be limited by sand supply. Giant dunes—stunning landforms that grow in patterns as wind blows sand grains over thousands of years—are measured across the entire planet for the first time. With this data, it’s shown the dunes can, in principle, grow in scale indefinitely.