Mountain-Wave Evolution and Orographic Precipitation

山脉形成了阻挡风流动的天然屏障。当风，特别是风暴接近山脉时，山波在屏障的上方和下游发展。与此同时，低层水流可能会受阻，并在山脉外围分流。这些流动的规模往往太小，无法被全球天气和气候模式准确捕捉，但会对必须参数化的大尺度流动产生拖累。这项研究包括两名研究生的培训和专业发展，其中包括一名代表性不足的少数民族。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助于水资源管理者、水文学家和那些研究我国气候现状和中纬度风暴未来潜在变化的人。本研究试图为参数化建立更坚实的理论基础。通过高分辨率数值模拟的分析，研究地形阻力的大尺度响应。山区的强降水在很大程度上是由大范围天气系统的通过所推动的。由于模拟大小尺度流动的复杂性，以前没有人对这些天气系统与理想化山脉的相互作用进行典型的理论研究。这项研究建立在先前对干燥气流中多尺度相互作用的研究的基础上，包括由于中纬度气旋和地形迫使的更局部上升而形成的湿润气流，形成强劲的上升气流和增强的降水。

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.