Mechanics of particle transport by wind

风携带和输送颗粒的现象发生在地球的各个大洲。干旱到半干旱地区主要受到影响，尽管受农业、采矿和建筑活动干扰的地点也受到通货紧缩和土壤肥力下降以及空气质量差的影响。与其他国家炎热的沙漠和草原相比，加拿大的风蚀是独一无二的，因为许多受影响的北部地区季节性寒冷和干燥，尽管夏季潮湿。同样，生物结壳在广阔的沿海海滩上蓬勃发展，那里的风比大陆沙漠大得多。实际上，科学家目前所知道的关于炎热干旱地区风中颗粒运输的知识很少适用于高纬度寒冷地区。这项研究计划旨在了解和量化风沙过程受给定表面向气流供应颗粒的限制的影响程度；例如，结壳、高湿度、孔冰和不可侵蚀的粗糙度元素的存在。特伦特环境风洞(TEWT)是目前世界上唯一一个在系统变化的温度和湿度范围内(包括冬季条件)研究沉积颗粒输送的设施。该设施的工作与实地科学家的工作相辅相成，但有一个优势，即研究这种环境控制所需的时间大大缩短了。众所周知，自然风蚀事件具有不可预测性和间歇性，因此很难进行高空间和时间分辨率的野外实验。例如，风洞模拟使研究人员能够使用粒子跟踪测速仪(PTV)研究现象的基本物理；以及对湍流特性进行详细的垂直和水平剖面图。从长远来看，这项研究计划的目标是更全面地了解全球范围内发生风蚀的条件范围，并为改进现有泥沙输送模型的开发和参数化做出贡献。

The entrainment and transport of particles by wind occurs on all continents of the Earth. Arid to semi-arid regions are principally affected, although sites disturbed by agriculture, mining and construction activities also are subject to deflation and reduced soil fertility, as well as, poor air quality. Wind erosion in Canada is unique as compared to the hot deserts and grasslands of other countries in the sense that many northern areas affected are seasonally cold and dry, though humid in summer. Similarly, biotic crusts flourish on expansive coastal beaches that are considerably windier than continental deserts. In effect, very little of what scientists currently know about the transport of particles by wind in hot, arid regions well applies to high latitude, cold regions. This research program aims to understand and quantify the degree to which aeolian processes are affected by constraints on the supply of particles from a given surface to the airflow; as for example, the presence of crusts, high humidity, pore ice, and non-erodible roughness elements. The Trent Environmental Wind Tunnel (TEWT) is the only facility in the world at present where the transport of sedimentary particles is studied over a systematically varied range of temperature and humidity, inclusive of winter time conditions. Work in this facility complements that of field scientists, but has the advantage that the time required to study such environmental controls is significantly compressed. Natural wind erosion events are notoriously unpredictable and intermittent, so that it is difficult to carry out field experiments with a high degree of spatial and temporal resolution. Wind tunnel simulation allows researchers to study the underlying physics of the phenomena using particle tracking velocimetry (PTV); as for example, as well as to carry out detailed vertical and horizontal profiling of the turbulent airflow properties. Over the long term, the goal of this research program is to comprehend more fully the range of conditions under which wind erosion occurs on a global scale, and to contribute to improvements in the development and parametrization of existing sediment transport models.