初期沙丘的时空演变
Spatial and temporal development of incipient dunes
摘要：
在松散的沙带中，由于平坦沉积床的线性不稳定性，风吹沙丘出现。这种不稳定性已经在实验和数值模型中进行了研究，但很少在现场，由于涉及的时间和长度尺度大。我们研究沙丘形成的上风边缘的白沙沙丘领域在新墨西哥州（美国），使用4年的激光雷达地形数据，以遵循空间和时间的发展初期沙丘。数据量化沙丘波长，增长率和传播速度，以及与增长过程相关的特征长度尺度。我们表明，所有这些测量结果都与线性稳定性分析的预测定量一致。这种验证使人们有可能使用的理论来可靠地解释沙丘格局的特点，并提供定量约束相关的风况和沉积物的属性，直接的本地测量是不可用或不可行的。
英文摘要：
In zones of loose sand, wind-blown sand dunes emerge due the linear instability of a flat sedimentary bed. This instability has been studied in experiments and numerical models but rarely in the field, due to the large time and length scales involved. We examine dune formation at the upwind margin of the White Sands Dune Field in New Mexico (USA), using 4 years of lidar topographic data to follow the spatial and temporal development of incipient dunes. Data quantify dune wavelength, growth rate, and propagation velocity and also the characteristic length scale associated with the growth process. We show that all these measurements are in quantitative agreement with predictions from linear stability analysis. This validation makes it possible to use the theory to reliably interpret dune-pattern characteristics and provide quantitative constraints on associated wind regimes and sediment properties, where direct local measurements are not available or feasible.
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