Dunes form where winds blow over a bed of mobile sediment grains — conditions that are common in our solar system. On Earth, dunes abound in arid continental interiors and along sandy coastlines. Dune fields have also been recognized on Venus, Mars, Saturn’s moon Titan, and Pluto. In response to the different boundary conditions and other environmental forcings, dunes adopt a rich diversity of shapes, sizes, and behaviors. Thus, people around the globe and over centuries have developed a rich vocabulary to describe dunes and their complexity. As a result, existing dune nomenclature often includes redundant terms with differing definitions across scientific communities. Previous studies have endeavored to link dune shape to environmental forcing, usually by means of correlation. Although instructive, correlation-based classifications can be misleading if not based on underlying mechanics or if dune morphogenetic classes are not uniquely defined. Here, we synthesize existing dune terminology and use the last two decades of research on dune morphodynamics to propose three complementary dune classification schemes based on: (1) descriptive dune geomorphology, (2) morphodynamic processes, and (3) fluid mechanics and physics of sediment transport. The first classification relates dune types to geomorphic setting, the presence or absence of vegetation or obstacles, and dune shape (including planform shape, and cross-sectional symmetry or asymmetry). Dune classes can be further subdivided where the direction of sand transport is known independently. The second classification relates dune types and shapes to bed properties (sand-covered vs partially starved bed) and wind forcing (directional variability or the relative strengths and directions of wind modes) that together influence dune dynamics (growth, migration, elongation) and select the dominant processes by which dunes are shaped and oriented relative to the resultant transport direction. The third classification relates, for different planetary environments, the range of possible dune sizes, from minimum to maximum wavelength, to fluid flow regime (rough or smooth) and the response of sediment flux, which influence the coupling between sand bed topography, fluid flow, and sediment transport. These characteristic lengths are useful scales for comparative geomorphology. The three classification schemes provide complementary information. Together, they form a unified framework for geomorphologists, sedimentologists, geographers, physicists, and others to describe windblown sand dunes on Earth and beyond through their shape, dynamics, and size as a response to winds and boundary conditions.

中文翻译：

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基于形态学、动力学和流体力学的风沙丘补充分类


沙丘是在风吹过移动沉积物颗粒床的地方形成的——这在我们的太阳系中很常见。在地球上，干旱的大陆内陆和沙质海岸线上沙丘比比皆是。金星、火星、土星的卫星泰坦和冥王星上也发现了沙丘区。为了应对不同的边界条件和其他环境强迫，沙丘呈现出丰富多样的形状、大小和行为。因此，几个世纪以来，世界各地的人们已经发展了丰富的词汇来描述沙丘及其复杂性。因此，现有的沙丘命名法通常包括科学界不同定义的冗余术语。先前的研究通常通过相关性的方式，试图将沙丘形状与环境强迫联系起来。尽管具有启发性，但如果不基于基础力学或沙丘形态生成类别没有唯一定义，基于相关性的分类可能会产生误导。在这里，我们综合了现有的沙丘术语，并利用过去二十年的沙丘形态动力学研究，提出了三种互补的沙丘分类方案，基于：（1）描述性沙丘地貌学，（2）形态动力学过程，以及（3）流体力学和物理学泥沙输送。第一个分类将沙丘类型与地貌环境、植被或障碍物的存在或不存在以及沙丘形状（包括平面形状和横截面对称或不对称）联系起来。当沙子运输的方向独立已知时，沙丘类别可以进一步细分。 第二类将沙丘类型和形状与沙床特性（沙床覆盖与部分贫瘠的沙床）和风力（方向变化或风模式的相对强度和方向）联系起来，共同影响沙丘动态（生长、迁移、伸长）并选择沙丘相对于最终运输方向成形和定向的主要过程。第三类涉及不同的行星环境，可能的沙丘尺寸范围（从最小到最大波长）、流体流动状态（粗糙或光滑）以及沉积物通量的响应，这影响沙床地形、流体流动之间的耦合和泥沙输送。这些特征长度是比较地貌学的有用尺度。这三种分类方案提供了补充信息。它们共同构成了地貌学家、沉积学家、地理学家、物理学家和其他人的统一框架，通过沙丘的形状、动态和大小来描述地球上及其他地区的风吹沙丘，作为对风和边界条件的响应。