Atmospheric boundary-layer studies and aeolian processes

无论是从草原农场带走表层土壤的夏季沙尘暴，沙漠中的沙尘暴，火星上的沙尘暴，还是导致能见度降低和其他危害的飘雪和吹雪，风成过程有许多非常实际的应用。我们可以模拟这些湍流中涉及的许多机制，并且已经这样做了，但是一个持续的不确定性和困难是如何处理在空气（或水）中吹动的物质与下表层之间的相互作用。蠕变、跳跃和悬浮的过程是这个过程中各个阶段的特征，这是已知的，但是尽管经过多年的研究，仍然缺乏一个连贯的建模策略。我们自己最近对地球上的雪和火星上的尘埃的研究（与NASA/CSA凤凰号着陆器有关），加上最近在模拟悬浮粒子过程方面的成功，促使了对风成运输过程这方面的基础研究，作为我们正在进行的大气边界层流动研究的主要部分。这项研究的方法将围绕湍流大气边界层流动的计算机模拟，有无悬浮和跳跃粒子的存在。我们在北极、亚北极、马尼托巴和安大略省对吹雪进行了实地研究，我们有这些研究的数据，我们将利用这些数据来产生想法，并为测试我们开发的模型提供数据。我们也是凤凰号火星任务的积极参与者，一旦着陆器于2008年在火星表面就位，我们将获得独特的数据。对于沙尘，我们还将在特伦特大学的风洞中进行风成过程的研究，并使用高分辨率摄影技术来研究颗粒表面的相互作用。在雪的情况下，粒子可以升华，或部分升华，从冰到水蒸气，从而改变其大小或完全消失，这就增加了复杂性。我们已经用我们的PIEKTUK（吹雪）模型模拟了这些过程，但还需要在我们的拉格朗日模拟研究中表示它们。拉格朗日模拟是一种模拟湍流中粒子运动的随机游走模型。

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.