科研之友
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摘要
Using automatic bedform mapping, principal component analysis and clustering we present a multiscale morphodynamic survey of dunes and meter-scale ripples on Herschel crater, Mars. The main purpose of this study is to assess if the morphology and temporal evolution of Martian meter-scale ripples is comparable to the morphodynamic characteristics of terrestrial aeolian impact ripples. We demonstrate that the spatial variations of the mapped dune patterns are correlated with substrate topography, which also influences the spatial distribution of the height and celerity of dunes' slipfaces. This topographic forcing is also patent on the spatial distribution of the ripples, thus proving that a multiscale coupling of active bedforms exists on Herschel under the present surface conditions. We found that Martian meter-scale ripples are morphologically distinct from terrestrial aeolian ripples, presenting a lower degree of straightness. Only similar to 3% of the mapped ripples can be considered sinuous or straight bedforms. Moreover, we conclude that this two-dimensional sub-population is restricted to well define dune settings, where factors that promote the elongation of the meter-scale ripples were identified: gravity transport on higher slopes, bedform obliquity and flow convergence on the leeward side of dunes. We also report that the different sets of ripples that were mapped and segmented do not present a transverse migration. Therefore we conclude that terrestrial aeolian ripples are not good analogues for Martian meter-scale bedforms, either in terms of morphology or dynamic evolution.
- 出版日期2017-6
