EAR-PF: Accounting for turbulent effects to improve prediction of sand and dust transport by wind

罗利·马丁博士被授予美国国家科学基金会地球科学博士后奖学金，他将在加州大学洛杉矶分校开展一项研究和教育计划。他将研究在自然沙漠和海滩环境中应对湍动风的沙子输送过程。这种沙子的输送形成了沙丘，而沙子反弹对沙漠土壤的轰击产生了沙尘暴。因此，能够预测输沙率与风速之间的关系是很重要的。现有的理论对恒定风下的沙粒输送提供了合理的预测，但这些预测在自然环境特有的湍流、快速波动的风条件下失效。沙粒运移速度的变化既滞后于近地表风速的变化，也与地面附近的风速变化相互反馈。通过现场观测支持的理论推理，该项目将量化波动的沙粒输送和湍动风之间的这些复杂相互作用，最终目标是改进对自然环境中沙粒输送的预测。该项目将自下而上地进行，从详细分析风沙相互作用开始，导致开发一种新的风沙模型，最终将该模型与描述自然环境中的湍流风联系起来。风沙模型的开发和验证将基于对自然环境中风速和沙子输送的高分辨率测量。除了增进我们对形成沙漠和沿海环境的基本过程的理解外，这项工作还将为解决粉尘污染、海岸保护和农业土壤侵蚀等问题提供基础。研究工作将与改善公众可获得和获取研究数据的倡议相结合。此外，将通过在当地一所小学为五年级学生开发实践地球科学项目来促进教育推广。

Dr. Raleigh Martin has been awarded an NSF Earth Sciences Postdoctoral Fellowship to carry out a research and education plan at the University of California, Los Angeles. He will investigate the process of sand transport in response to turbulent winds in natural desert and beach environments. This sand transport forms sand dunes, and the bombardment of desert soils by bouncing sand produces dust storms. It is therefore important to be able to predict how the rate of sand transport is related to the speed of blowing wind. Existing theory provides reasonable predictions for sand transport under constant winds, but these predictions break down under the turbulent, rapidly-fluctuating wind conditions characteristic of natural environments. Changes in the rate of sand transport both lag and feed back onto changes in wind speed near the ground surface. Through theoretical reasoning supported by field observations, this project will quantify these complex interactions between fluctuating sand transport and turbulent winds, with the ultimate goal of improving predictions of sand transport in natural environments. The project will proceed from the bottom up, beginning with a detailed analysis of wind-sand interactions, leading into development of a new model for wind-blown sand, and culminating in a linkage of this model to descriptions of turbulent winds in natural environments. Development and validation of the wind-blown sand model will be based on coupled high-resolution measurements of wind speed and sand transport in natural environments. In addition to advancing our understanding of a basic process that shapes deserts and coastal environments, this work will provide the basis for addressing such issues as dust pollution, coastal protection, and agricultural soil erosion. Research efforts will be coupled to initiatives to improve the public availability and accessibility of research data. Furthermore, educational outreach will be fostered through development of hands-on earth science projects for fifth-grade students at a local elementary school.