Atmospheric boundary-layer studies and aeolian processes

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Whether it is a summer dust storm removing topsoil from prairie farms, a sandstorm in the desert, a dust storm on Mars or drifting and blowing snow causing reduced visibility and other hazards, there are many very practical applications of aeolian processes.  We can model many of the mechanisms involved in these turbulent flows, and have done so, but a continuing uncertainty and difficulty is how treat the interaction between the material blowing in the air (or water) and the underlying surface. The processes of creep, saltation and suspension that characterise various stages in this process are known, but a coherent modelling strategy is missing, despite many years of research. Our own recent work on blowing snow on Earth and dust on Mars (in connection with the NASA/CSA Phoenix lander), coupled with recent success in modelling suspended particle processes has prompted the fundamental study of this aspect of the aeolian transport process as a major part of our ongoing studies of atmospheric boundary-layer flows. Methods for this study will revolve around computer modelling of turbulent atmospheric boundary-layer flows, with and without the presence of suspended and saltating particles. We have data from our own ongoing field studies of blowing snow, in the Arctic, sub-Arctic, Manitoba and Ontario, and will use these to generate ideas and provide data for testing the models we develop. We are also active participants in the Phoenix mission to Mars and will have access to unique data once that lander is in place on the surface of Mars in 2008. For sand and dust we will also conduct studies in the aeolian processes wind tunnel at Trent University and use high resolution photographic techniques to study particle surface interactions. In the case of snow there are added complications in that particles can sublimate, or partially sublimate, from ice to water vapour, thereby changing their size or completely disappearing. We have already simulated these processes with our PIEKTUK (blowing snow) model, but also need to represent them in our Lagrangian simulation studies. Lagrangian simulation is a type of random walk model which simulates the movement of particles in a turbulent flow.