Vertical profiles, size distributions, and intermittency in aeolian sediment transport: Field measurements with a novel instrument

项目摘要：风沙输送中的垂直剖面、粒度分布和间歇性：一种新型仪器的现场测量在两个不同的现场部署中，作为该项目的一部分开发的一种仪器将用于经济地测量在风的影响下沙粒移动的速度和大小，这一过程被称为风沙输送。这台绰号为SANTRI的仪器将利用廉价的光学传感器和风传感器来测量沙子移动所需的门槛风速和沙子通量的大小，时间分辨率约为一秒。初步的中试测试表明，除了聚集砂流量外，这些传感器还可以提供有价值的粒度信息，可能还包括速度信息。与目前可用的其他仪器相比，包括那些使用光学传感器的仪器，SANTRI将更加独立，不需要外部数据捕获、电力或频繁维修。在通过现有NSF项目建立的外地地点部署将提供必要的信息，以确定需要改进的领域。在另一个选定的现场进行第二次部署，将提供在不同风力条件下沙子运动的大型数据集。后一项工作的结果可以用于物理模型的测试。风沙的移动是悬浮沙尘的主要过程，沙尘是全球最大的大气气溶胶成分。在土壤表面被风的剪切力放出的沙粒，在随后对土壤的冲击时，可能会导致更多的沙粒和更小的气溶胶大小的尘埃颗粒被抛出。自从科学文献中出现了关于这一主题的第一批开创性著作以来，这一跃迁过程一直是风吹或风沙沉积物运移研究的中心主题。在了解跃迁是如何启动的、植被和其他地表粗糙度的影响以及土壤参数(如水分)的影响方面，已经取得了重大进展。然而，准确模拟特定土壤在特定风力条件下的行为的能力仍然是一个主要的挑战，由于现场测量的相对缺乏，这一挑战变得更加困难，部分原因是这些测量具有劳动密集型和成本密集型的性质。这项研究将导致开发一种新的、经济的和变革性的仪器，它有可能开辟新的调查路线，并使收集现场测量数据来测试已经建立的模型变得更加困难，这些模型一直严重依赖实验室风洞实验而不是真实世界的数据。通过改进模型和更稳健的数据集，可以更彻底地了解影响气候、积雪融化速度、土地退化和人类健康的地方、区域和全球风尘排放。

Project Abstract: Vertical profiles, size distributions, and intermittency in aeolian sediment transport: Field measurements with a novel instrumentIn two separate field deployments, an instrument that will be developed as part of this project will be used for the economical measurement of the rate and magnitude of the movement of sand under the influence of wind, a process referred to as eolian sand transport. The instrument, nicknamed the SANTRI will utilize inexpensive optical sensors in conjunction with wind sensors to measure the threshold winds required for the movement of sand and the magnitude of the sand flux with time resolution on the order of one second. Preliminary pilot tests indicate that in addition to aggregate sand flux, these sensors can provide valuable grain size, and possibly speed information. Compared to other instruments that are currently available, including those that use optical sensors, the SANTRI would be much more independent, requiring no external data capture, electrical power, or frequent servicing. Deployment at a field site that has been established through an existing NSF project will provide the information necessary to identify areas for improvement. A second deployment at another selected field site will provide a large dataset of sand movement under varying wind conditions. Results from this latter effort can be used for testing of physical models.Movement of sand by wind is the principal process that suspends dust, the largest atmospheric aerosol constituent on a global basis. Sand grains that are lofted by the shearing forces of the wind at the soil surface can, upon subsequent impact on the soil, cause the ejection of additional sand grains and much smaller, aerosol-sized dust particles. This saltation process has been a central subject of windblown, or eolian, sediment transport research since the first seminal writings on the topic appeared in the scientific literature. Significant progress has been made in understanding how saltation is initiated, the effect of vegetation and other surface roughness, and the influence of soil parameters such as moisture. However, the ability to accurately model the behavior of a specific soil under specific wind conditions continues to be a primary challenge, one that is made more difficult by a relative paucity of in-situ measurements, owing in part to the labor- and cost-intensive nature of these measurements.This research will result in the development of a new, economical, and transformative instrument that has the potential to open up new lines of inquiry and enable the collection of field measurements to test established models that have been relying heavily on laboratory wind tunnel experiments instead of real-world data. Through improvement of models and more robust datasets, a more thorough understanding can be obtained of local, regional, and global emissions of windblown dust, which impacts climate, rate of snow melt, land degradation, and human health.