Two scales of ripples form in fine sand on Mars. The larger ripples were proposed to have an equilibrium size set by an aerodynamic process, making them larger under thinner atmospheres and distinct from smaller impact ripples. Sullivan et al. (2020, https://doi.org/10.1029/2020JE006485) show that large ripples can develop in a numerical model due to Mars’ low atmospheric pressure. Although their proposed growth‐limiting mechanism is consistent with an aerodynamic process, they argue that the ripples in their model are simply large versions of impact ripples, not a separate class of ripples. Here, we explore this debate by synthesizing recent advances in large‐ripple formation (including initiation and subsequent evolution to equilibrium). Although significant knowledge gaps remain, it is clear that large Martian ripples in well sorted sand are larger under thinner atmospheres, and thus remain a powerful paleoclimate indicator.

中文翻译：

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对火星上神秘的大涟漪的不断发展的理解

在火星上的细沙中形成了两个鳞片的涟漪。提出较大的波纹具有通过空气动力学过程设定的平衡尺寸，从而使其在较薄的大气下更大，并且与较小的冲击波纹不同。Sullivan等。（2020，https://doi.org/10.1029/2020JE006485）显示，由于火星的大气压力低，在数值模型中可能会形成较大的波纹。尽管他们提出的增长限制机制与空气动力学过程一致，但他们认为模型中的波纹只是冲击波纹的大版本，而不是单独的波纹类别。在这里，我们通过综合大波纹形成的最新进展（包括引发和随后向平衡的演化）探讨这一争论。尽管仍然存在重大的知识差距，