Satellite remote sensing and field analyses of megaripples and dunes in the Skeleton Coast National Park, Namibia

The morphology of aeolian bedforms is controlled by the boundary conditions during their formation and evolution, playing a crucial role in reconstructing current and past environmental settings. This study investigates the morphology and dynamics of multiscale aeolian bedforms, specifically megaripples and barchan dunes, in Namibia's Skeleton Coast National Park using satellite remote sensing, reanalysis wind data, and field observations. Newly mapped megaripples show average wavelengths between 3.3 and 4.4 m, with crest orientations aligned predominantly with regional southerly winds. Remote sensing data reveal a dune migration rate of ∼30 m yr⁻¹ and an average sand flux of ∼140 m³ m⁻¹ yr⁻¹, while field-based storm observations yield a peak flux of 256 m³ m⁻¹ yr⁻¹. A novel correlation between armoring layer thickness and grain-size median (D₅₀) suggests a feedback loop where larger grains promote ripple growth. Seasonal wind shifts inferred from dune patterns and wind streaks are corroborated by ERA5 reanalysis, indicating a dynamic yet low-energy aeolian system. The results provide insights into sediment transport mechanisms across scales, the evolution of ripple morphometry, and grain-size feedbacks influencing megaripple formation, offering valuable analogs for similar processes on Mars. This multiscale assessment supports improved modeling of terrestrial and planetary aeolian systems.