Mechanics of particle transport by wind

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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.