Long‐Wavelength Sinuosity of Linear Dunes on Earth and Titan and the Effect of Underlying Topography

Abstract

On both Earth and Titan, some linear dunefields are characterized by curvilinear patterning atypical of the regularity and straightness of typical longitudinal dunefields. We use remotely sensed imagery and an automated dune crestline detection algorithm to analyze the controls on spatial patterning. Here it is shown that topography can influence the patterning, as dune alignments bend to deflect downslope under the influence of gravity. The effect is pronounced in a terrestrial dunefield (the Great Sandy desert, Australia) where substantial topography underlies, but is absent where the dunefield is underlain by subdued relief (southwestern Kalahari). This knowledge allows the inference of subtle topographic changes underlying dunefields from dunefield patterning, where other sources of elevation data may be absent. This methodology is explored using the Belet Sand Sea of Titan, where likely areas of topographic change at resolutions finer than those currently available from radar altimetry are inferred.

Planetary Aeolian Landforms: An Introduction to the Fifth Planetary Dunes Workshop Special Issue

“…This is key to correctly choosing the safest and scientifically compelling landing sites for future missions (Chojnacki et al., 2018; Telfer et al., 2019). The analysis of terrestrial analogs from orbiters and direct field observation together with laboratory experiments are fundamental in this regard (Bristow & Moller, 2018; Telfer et al., 2019; Wang et al., 2018; Yu et al., 2018). Erosional features like yardangs and ghost dune pits need more detailed studies to better understand their evolutionary history and formation timescales both on Mars and Earth (Day & Catling, 2018; Wang et al., 2018).…”

“…Local topography that cannot be resolved with current data could pose a threat to future landing missions. Telfer et al (2019), while not proposing a technique to fully recover local topography from curvilinear dunes, did suggest avoiding these regions as a landing site in order to reduce risk.…”

“…In this issue, Telfer et al. (2019) suggested that the curvilinear features are a result of underlying topography. They examined two terrestrial analog dune fields, one in Australia and one in southern Africa.…”

“…Telfer et al. (2019) suggested these deflections were a result of the underlying topography inducing down‐slope deflections, where steeper slopes cause greater deflections. However, the DTMs for the region did not have sufficient resolution to be sensitive to local topography.…”

Titan: Earth-like on the Outside, Ocean World on the Inside

“…Perhaps the best studied sediments on Titan are the organic sands that occupy 17% of the moon's surface (Soderblom et al 2007;Barnes et al 2008;Bonnefoy et al 2016;Le Gall et al 2011Rodriguez et al 2014;Brossier et al 2018). Linear dunes (100s of kilometers long and ∼100 m in height) demonstrate the importance of aeolian processes and underlying topography in the redistribution of Titan's organics (Rodriguez et al 2014;Radebaugh et al 2008Radebaugh et al , 2010Lorenz & Radebaugh 2009;Malaska et al 2016b;Paillou et al 2016;Telfer et al 2019). Titan's vast mid-latitude plains (∼65% of the surface) are also hypothesized to consist of organic materials (Malaska et al 2016a;Lopes et al 2016Lopes et al , 2020Solomonidou et al 2018;MacKenzie et al 2019a), but their composition and origin remains unknown.…”