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

项目摘要：垂直剖面，粒度分布，风成沉积物运输的不透明度：现场测量与一种新的仪器在两个独立的现场部署，一个仪器，将被开发作为本项目的一部分，将用于经济的测量速度和规模的运动的沙子在风的影响下，一个过程被称为风成沙运输。该仪器绰号为SANTRI，将利用廉价的光学传感器和风传感器测量沙粒移动所需的临界风速和沙粒通量的大小，时间分辨率为一秒。初步试验表明，除了总砂流量，这些传感器可以提供有价值的粒度，并可能速度信息。与目前可用的其他仪器（包括使用光学传感器的仪器）相比，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项目建立的现场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，将提供不同风力条件下沙子运动的大型数据集。这后一项工作的结果可用于测试物理模型，风吹沙动是悬浮尘埃的主要过程，而尘埃是全球最大的大气气溶胶成分。在土壤表面被风的剪切力扬起的沙粒，在随后对土壤的影响下，会导致更多的沙粒和更小的气溶胶大小的尘埃颗粒喷射出来。这种跃移过程一直是风吹或风成沉积物输运研究的中心主题，因为第一个开创性的著作出现在科学文献中。在了解跃移是如何开始的、植被和其他表面粗糙度的影响以及湿度等土壤参数的影响方面取得了重大进展。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而变得更加困难，部分原因是这些测量的劳动力和成本密集型。这项研究将导致开发一种新的，经济的，这是一种具有变革性的仪器，有可能开辟新的调查路线，并能够收集现场测量数据，以测试严重依赖实验室风洞实验而不是真实世界数据的既定模型。通过改进模型和更强大的数据集，可以更全面地了解地方，区域和全球的风沙排放，这会影响气候，积雪融化率，土地退化和人类健康。

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.