Mountain-Wave Evolution and Orographic Precipitation

山脉形成了风的天然屏障。当风，特别是风暴接近山脉时，山浪在屏障的上方和下游形成。与此同时，低层气流可能在山脉外围被阻塞和分流。这些气流通常规模太小，无法被全球天气和气候模式准确捕捉，但却对必须参数化的大尺度气流产生阻力。这项研究包括两名研究生的培训和专业发展，其中包括一名未被充分代表的少数民族。研究结果将通过期刊文章和会议报告分享，包括由美国气象学会（AMS）山地气象委员会组织的网络研讨会。这项研究的结果也将有利于水资源管理者、水文学家和那些研究我们的气候现状和中纬度风暴未来潜在变化的人。本研究试图将参数化建立在更坚实的理论基础上。通过高分辨率数值模拟分析，对地形阻力的大尺度响应进行了研究。山区强降水主要是由大尺度天气系统的通过所驱动的。由于模拟大、小规模气流的复杂性，这些天气系统与理想山脉相互作用的原型理论研究以前没有进行过。本研究建立在先前关于干燥气流多尺度相互作用的研究基础之上，其中包括湿润气流，这是中纬度气旋和地形迫使更多局部上升形成强烈上升气流和降水增强的结果。

Mountains form natural barriers to wind flow. As winds in general, and storms in particular, approach mountain ranges, mountain waves develop above and downstream of the barrier. At the same time, low-level flow may become blocked and diverted around the periphery of the mountains. These flows are often too small in scale to be accurately captured by global weather and climate models, but produce drag on the large-scale flow that must be parameterized. This research includes the training and professional development of two graduate students, including one under-represented minority. Results will be shared through journal articles and conference presentations, including webinars organized by the Mountain Meteorology Committee of the American Meteorological Society (AMS). The results of this research will also benefit water resource managers, hydrologists and those studying the current state of our climate and potential future shifts in mid-latitude storms.This study attempts to place parameterization on a firmer theoretical foundation. The large-scale responses to orographic drag will be studied through the analysis of high-resolution numerical simulations. Heavy precipitation over mountains is largely driven by the passage of large-scale weather systems. Prototypical theoretical studies of the interactions of these weather systems with idealized mountain ranges have not previously been undertaken due to the complexity of modeling large- and small-scale flows. This research builds on prior studies of multi-scale interactions in dry air flow by the inclusion of moist flow as a result of the combination of mid-latitude cyclones and more localized ascent forced by topography into vigorous updrafts and enhanced precipitation.