NSFGEO-NERC: The Origin of Aeolian Dunes (TOAD)

NSFGEO-NERC：风沙丘的起源 (TOAD)

• 批准号: NE/R010196/1
• 负责人: Joanna Nield
• 金额: $ 64.96万
• 依托单位: University of Southampton
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2018
• 资助国家: 英国
• 起止时间: 2018 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FR010196%2F1
• 关键词: NSFGEO; NERC; Origin; Aeolian; Dunes

Aeolian (wind-blown) sand dunes occupy 10% of the Earth's surface, both in vast desert sand seas and as important natural defences against flooding along coasts. While the environmental conditions that influence the shape, movement and patterns of fully grown dunes have been extensively studied, arguably the most enduring deficiency in our understanding of these landforms is also the most profound: how do wind-blown dunes initiate?Initiation is central to understanding dunes as major geological units, including the response of these landscapes to climatic drivers, environmental change and societal impact. The significance of dune initiation for the wider understanding of wind-blown sandy systems and their contexts, for which the discovery of extra-terrestrial dune fields has added a recent impetus, ensures that the question of initiation has remained prominent throughout the history of desert research. Despite this, existing ideas proposed to explain processes of dune origin have remained largely descriptive and uncorroborated. The persistence of the question regarding dune initiation is not due to an absence of appreciation of its importance but, rather, a lack of the means to tackle this fundamental issue. The critical obstacle to a fully developed understanding of dune initiation is that, until now, measurement of the necessary variables, at the ultra-high spatial and temporal resolutions required to detect small-scale variations in surface conditions and wind-blown sand transport, has been impossible. Recent technological advances in the geosciences both inspire and underpin this proposal, as they now provide the opportunity to meet the demanding requirements of process measurement. Surmounting the abiding problem of dune initiation requires novel approaches in research design and our proposal tackles the issues of measurement at small scales by forging complementary links between fieldwork and physical modelling, as well as an ability to widen the application of detailed process findings through computer modelling. Specifically, this proposal will for the first time examine the key inter-relationships between airflow, surface properties, changes in sand transport and bedform shape that lie behind a meaningful understanding of how nascent dunes emerge. Full measurement of controlling processes and bedform development will be achieved through field monitoring of surface properties and bedform change at extremely high resolution. A key novelty of the fieldwork is that it will be carried out at three carefully chosen locations of known dune development, with each location representing the 'type site' for three different drivers of dune initiation; surface roughness, surface moisture and sand bed instability. The fieldwork will inform experiments undertaken in a bespoke laboratory flume that is designed to enable accurate characterisation of flow very close to the 3D surface of modelled dunes using state-of-the-art imaging techniques. Our field and laboratory dataset will be used to drive a computer model that we will then run to test the sensitivity of dune initiation and growth to different controls in a range of environmental conditions in deserts, coasts and on other planets. Our proposal is built on a new capability to make field observations at the requisite exceptional levels of detail, augmented by closely coupled state-of-the-art laboratory flow simulations, plus the development and application of evidence-based modelling to examine drivers of dune initiation. In concert, this approach represents an unprecedented opportunity to overcome a truly enduring plateau for understanding the origins of one of the major terrestrial landform systems.

风成沙丘占据了地球表面的10%，无论是在广阔的沙漠沙海中，还是作为沿着抵御洪水的重要天然屏障。虽然环境条件影响的形状，运动和模式的充分成长的沙丘已被广泛研究，可以说是最持久的缺陷，我们对这些地貌的理解也是最深刻的：风吹沙丘如何启动？启动是理解沙丘作为主要地质单元的核心，包括这些景观对气候驱动因素，环境变化和社会影响的反应。沙丘萌生对于更广泛地了解风吹桑迪系统及其背景具有重要意义，地外沙丘场的发现最近为其增添了动力，确保了萌生问题在整个沙漠研究史上仍然是突出的。尽管如此，现有的想法提出来解释沙丘的起源过程仍然主要是描述性的和未经证实的。沙丘形成问题的持续存在并不是因为没有认识到其重要性，而是因为缺乏解决这一根本问题的手段。充分了解沙丘形成的关键障碍是，到目前为止，一直无法以超高的空间和时间分辨率测量必要的变量，以探测地表条件和风沙输送的小尺度变化。地球科学的最新技术进步既激发又支持了这一提议，因为它们现在提供了满足过程测量苛刻要求的机会。克服沙丘形成的持久问题需要研究设计中的新方法，我们的提案通过建立实地工作和物理建模之间的互补联系以及通过计算机扩大详细过程发现的应用的能力来解决小尺度测量问题。建模。具体而言，该提案将首次研究气流，表面特性，沙输送变化和床形形状之间的关键相互关系，这些关系对新生沙丘的形成有意义的理解。控制过程和底形发展的全面测量将通过以极高分辨率对表面特性和底形变化进行现场监测来实现。实地考察的一个关键新奇在于，它将在三个精心选择的已知沙丘发育位置进行，每个位置代表沙丘形成的三个不同驱动因素的“类型站点”;表面粗糙度，表面水分和砂床不稳定性。实地考察将为在定制的实验室水槽中进行的实验提供信息，该水槽旨在使用最先进的成像技术精确表征非常接近模拟沙丘的3D表面的流动。我们的现场和实验室数据集将用于驱动计算机模型，然后我们将运行该模型，以测试沙丘形成和生长对沙漠，海岸和其他星球上一系列环境条件下不同控制的敏感性。我们的建议是建立在一个新的能力，使实地观察在必要的特殊水平的细节，增强了紧密结合的国家的最先进的实验室流动模拟，再加上开发和应用的证据为基础的建模，以检查驱动程序的沙丘启动。在音乐会上，这种方法代表了一个前所未有的机会，克服一个真正持久的高原了解一个主要的陆地地貌系统的起源。

项目成果

Dune Initiation in a Bimodal Wind Regime

• DOI: 10.1029/2020jf005757
• 发表时间: 2020-11-01
• 期刊: JOURNAL OF GEOPHYSICAL RESEARCH-EARTH SURFACE
• 影响因子: 3.9
• 作者: Delorme, Pauline;Wiggs, Giles F. S.;Valdez, Andrew
• 通讯作者: Valdez, Andrew

Topographic perturbation of turbulent boundary layers by low-angle, early-stage aeolian dunes

低角度早期风成沙丘对湍流边界层的地形扰动

• DOI: 10.1002/esp.5326
• 发表时间: 2022
• 期刊: Earth Surface Processes and Landforms
• 影响因子: 3.3
• 作者: Bristow N

Field Evidence for the Initiation of Isolated Aeolian Sand Patches

• DOI: 10.1029/2022gl101553
• 发表时间: 2023-01
• 期刊: Geophysical Research Letters
• 影响因子: 5.2
• 作者: P. Delorme;J. Nield;G. Wiggs;M. Baddock;N. Bristow;J. Best;K. Christensen;P. Claudin

Local Wind Regime Induced by Giant Linear Dunes: Comparison of ERA5-Land Reanalysis with Surface Measurements

• DOI: 10.1007/s10546-022-00733-6
• 发表时间: 2022-08
• 期刊: Boundary-Layer Meteorology
• 影响因子: 4.3
• 作者: C. Gadal;P. Delorme;C. Narteau;G. Wiggs;M. Baddock;J. Nield;P. Claudin