Mechanics of particle transport by wind

风对颗粒的夹带和输送发生在地球的所有大陆上。受影响的主要是干旱和半干旱地区，尽管受农业、采矿和建筑活动干扰的地点也会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，加拿大的风蚀是独特的，因为许多受影响的北方地区季节性寒冷和干燥，尽管夏季潮湿。同样，生物壳在广阔的沿海海滩上蓬勃发展，这些海滩比大陆沙漠风大得多。实际上，科学家目前对炎热干旱地区风中颗粒物传输的了解很少适用于高纬度寒冷地区。该研究计划旨在了解和量化风沙过程受特定表面向气流供应颗粒的限制的影响程度;例如，存在结壳，高湿度，孔隙冰和不可侵蚀的粗糙度元素。特伦特环境风洞（TEWT）是目前世界上唯一的设施，在系统变化的温度和湿度范围内，包括冬季条件下研究沉积颗粒的运输。该设施的工作补充了实地科学家的工作，但其优点是研究这种环境控制所需的时间大大缩短。众所周知，自然风蚀事件是不可预测和间歇性的，因此很难进行具有高度空间和时间分辨率的实地实验。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学;例如，以及对湍流气流特性进行详细的垂直和水平分析。从长远来看，这项研究计划的目标是更全面地了解在全球范围内发生风蚀的条件范围，并有助于改进现有泥沙输运模型的开发和参数化。

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.