Geophysical mechanisms governing particle transport by wind

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Wind is ubiquitous at Earth's surface, as well as on other planetary bodies such as Mars, Venus and Titan. Where any source of loose particles exists, the fluid drag of the wind may entrain and carry some fraction of these particles over distances varying from just a few millimeters to several meters and ultimately in the case of dust in long-term suspension, over thousands of kilometers. As such, the transport of these particles may affect air quality, visibility, the absorption and transmission of solar radiation, climate, soil fertility, and through deposition, surface topography (e.g. dunes).       While technically any form of particle can be transported in an airflow, my long-term research program funded by the NSERC Discovery Grant program is primarily focused upon natural sedimentary particles. My principal methodological approach is founded on the use of a boundary-layer wind tunnel to study the geophysical processes that govern particulate matter (PM) transport in air flows. Less than a half dozen such facilities in the world are typically engaged in work of this type at any given point in time. The Trent Environmental Wind Tunnel (TEWT) is distinguished as supporting one of the longest standing and most continuous research programs investigating (aeolian) sedimentary processes. It also is the only one of its type to be located in an environmental chamber with full climate control down to subfreezing temperatures. Laser based technologies available within TEWT include Particle Tracking Velocimetry (PTV) for investigating particle dynamics; Laser Doppler Anemometry (LDA) for sampling the properties of the airflow structure and particle kinetic; and LiDAR for mapping the surface morphometry.       The proposed work will use the leading-edge technologies available within TEWT to investigate: i) the dynamics of discrete particle impacts and ejections during their transport across wet and frozen sedimentary bed surfaces, ii) particle impact, splash, creep and segregation during the inception, growth and migration of ballistic ripples as found on a range of planetary surfaces, iii) the role of turbulence generation in dust emission and dispersion, and iv) the role of aggregate disintegration in dust generation. Each of these studies will increase understanding of the geophysical system, provide direct measurements for the parameterization and calibration of various sediment transport and dust emission models, and may ultimately lead to improvements in practices that aim to mitigate wind erosion and improve air quality. Training will be provided for six graduate students (2 PhD and 4 MSc) and five senior undergraduate thesis students, who will undertake this work and contribute to its dissemination through conference presentations and publication.