Remote sensing techniques in the investigation of aeolian sand dunes: A review of recent advances

Sand dunes are one of the most abundant aeolian landforms and play an important role in understanding how aeolian environments evolve. Since the 1970s, remote sensing has enabled large-scale investigations of dunes at comparatively low costs and with temporally continuous observations, which greatly advances our knowledge of aeolian systems. In this context, we provide a review of recent progress in three research topics that have been greatly facilitated by remote sensing techniques. These topics are 1) mapping sand extent and dune types, 2) dune pattern quantification, and 3) monitoring dune dynamics. Sand dune mapping was the early focus of aeolian geomorphologists, and continued progress has been made in refining classification schemes and developing advanced classification techniques. Dune pattern quantification can be resolved in two geomorphometric approaches, and a careful design that takes into consideration the image resolution, the data quality, and the uncertainty in dune discretization is necessary. Dune dynamics typically exhibit as dune migration, dune interactions, and dune fine-scale morphodynamics. The wide application of change detection algorithms, especially COSI-Corr, provides great insights into dune migration, while the exploration of dune interactions is still in its infancy. Future directions are highlighted in four key areas: unifying classification schemes regarding dune morphology, developing methods that are capable of recognizing diverse dune forms at large spatial extents, designing modularized workflows and more complex matching rules to quantify dune migration, and improving quantitative analysis of dune interactions.