Collaborative Research: Observing and Modeling Downslope-windstorm-type Flow in a Small-scale Crater Induced by Larger-scale Katabatic Winds

这项工作将调查具有重要社会影响但科学上知之甚少的下坡风暴类型气流(DWF)。该计划包括在亚利桑那州巴林格陨石坑进行为期一个月的实地考察，并使用大涡模拟(LES)模型进行模拟。之前NSF资助的一个研究项目中的一个偶然发现确定了这个位置非常适合进行这样的研究，因为在晴朗、未受干扰的夜晚，当热驱动的排水流级联到火山口边缘时，DWF会定期在那里产生。陨石坑的边缘和周围的尺度可以很容易地用仪器来研究这些流动以及导致它们形成的不断变化的上游条件。当接近的气流的温度和风廓线发生脉动时，在小型圆形陨石坑盆地的上风内侧壁上间歇性地产生DWF。因此，这项工作将支持在一个可能在相对较短的时间内进行多次复制的地点对DWF进行系统调查。2013年秋季的一项相关实地工作将收集特别适合于支持分析的数据，以回答有关地形上密度分层流动产生的大气DWF的现有科学问题。将利用多个LiDAR(光探测和测距)和SODAR(声波探测和测距)平台、系留气球探测系统以及红外延时相机和地面气象仪器对大气边界层条件进行详细采样。这个合作小组将进行的协调实地研究、分析和大涡模拟(LES)模拟的首要目标是确定与DWF相关的特征大气结构和演变，确定驱动DWF的katabatic风中的控制参数，并通过模拟研究将研究结果扩展到不同大小和形状的盆地和山脊，以更全面地了解DWF。这项研究的智力价值在于应用了新颖和创新的概念，最终将产生更全面的分析和建模，包括实地经验、简短的气候学以及初步的分析和模拟。这些努力将促进对影响复杂地形中大气DWF发展的物理过程的理解，并有望导致模型的改进和对这种普遍存在于世界各地山区的现象的理解。这一努力的广泛影响将包括支持本科生和研究生的培训，为课堂教学开发模块，以及博士后研究人员的职业生涯早期发展。通过改善对大气离散波函数的理解，将为社会带来潜在的好处，并可能应用于下坡风暴预报、空气污染扩散、一般和火灾天气预报以及气候。结果将通过同行评议的科学出版物、在科学会议上的陈述和相关网站广泛传播。

This effort will investigate downslope windstorm-type flows (DWF) that have important societal effects and are poorly understood scientifically. The program includes a one-month field program at Arizona's Barringer Meteorite Crater and simulations with a Large-Eddy-Simulation (LES) model. A serendipitous discovery in a prior NSF-funded research program identified this location as being ideally suited for such a study, as DWFs develop there regularly when thermally driven drainage flows cascade over the crater's rim on clear, undisturbed nights. The crater's rim and environs are on a scale that can be readily instrumented to investigate these flows and the changing upstream conditions that cause them to form. DWFs are produced intermittently on the upwind inner sidewall of the small, circular crater basin as pulsations occur in the temperature and wind profiles of the approaching flow. This effort will thus support a systematic investigation of DWFs at a location where many replications can be expected over a comparatively short period.An associated field effort during Autumn 2013 will collect data uniquely suited to support analyses to answer extant scientific questions about atmospheric DWFs produced by density-stratified flow over topography. Detailed sampling of atmospheric boundary layer conditions by multiple LiDAR (Light Detection And Ranging) and SoDAR (SOnic Detection And Ranging) platforms, tethered balloon sounding systems, as well as infrared time-lapse cameras and surface-based meteorological instrumentation, will be utilized. The overarching goal of the coordinated field research, analysis, and large-eddy simulation (LES) modeling to be conducted by this collaborative team is to determine the characteristic atmospheric structure and evolution associated with the DWFs, identify controlling parameters in the katabatic winds that drive DWFs and, through the modeling studies, extend the findings to basins and ridges of different size and shape to gain a more general understanding of DWFs. The intellectual merit of this research rests in application of novel and innovative concepts that will culminate in more comprehensive analyses and modeling informed by field experience, a short climatology, and initial analyses and simulations. These efforts will advance understanding of the physical processes that affect atmospheric DWF development in complex terrain, and are expected to lead to improvements in models and understanding of this ubiquitous phenomenon, which occurs in mountainous regions throughout the world.Broader Impacts of this effort will include support of undergraduate and graduate student training, development of modules for classroom teaching, and early-career development of a postdoctoral researcher. Potential benefits to society will accrue through improved understanding of atmospheric DWFs with potential applications for forecasting of downslope windstorms, air pollution dispersion, general and fire weather forecasting, and climate. Results will be widely disseminated through peer-reviewed scientific publications, presentations at scientific meetings, and related websites.