Numerical Modeling of Mesoscale Airflow over Mountains

山区中尺度气流的数值模拟

• 批准号: 9218376
• 负责人: Dale Durran
• 金额: $ 32.3万
• 依托单位: University of Washington
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1993
• 资助国家: 美国
• 起止时间: 1993-03-15 至 1996-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9218376&HistoricalAwards=false
• 关键词: Numerical; Modeling; Mesoscale; Airflow; over

Accurate weather forecasting in the vicinity of major mountain ranges is an extremely difficult meteorological problem. Interactions between large-scale weather systems and mountainous regions often spawn complex mesoscale weather patterns. Efforts to forecast the development of these weather patterns are limited by deficiencies in understanding of the physical processes governing mesoscale circulations in complex terrain. Additionally, mesoscale orographic effects also influence the global circulation through the action of gravity wave drag. Errors in the parameterization of gravity wave drag in global scale modes are believed to be a major source of error in extended range forecasts. Under previously supported research on this topic the Principal Investigator has found that vertically propagating mountain waves appear to be not as sensitive to the asymmetry of the underlying terrain as previously thought. Using free slip conditions, he has found that maximum lee slope winds also are not sensitive to asymmetry of the terrain. When surface friction is included, however, sensitivity to terrain is enhanced, but the primary regulator of maximum winds appears to be the steepness of the lee slope. The Principal Investigator will continue this line of research with the ultimate goal of improving weather forecasts for locations in the vicinity of mountains and to improve extended range forecasts and climate models. The major areas of concentration are: investigation of airflow in complex three-dimensional topography with emphasis on mountain barriers with and without mountain gaps, and isolated mountain peaks; study of momentum fluxes in orographically forced gravity waves and the interactions of these waves with the larger scale flow through gravity wave drag.

在主要山脉附近进行准确的天气预报是一个极其困难的气象问题。 大型天气系统与山区之间的相互作用通常会产生复杂的中尺度天气模式。 预测这些天气模式的发展的努力受到理解有关复杂地形中尺度循环的物理过程的缺陷的限制。 此外，中尺度的地形效应还通过重力波阻力的作用影响全局循环。 在全球尺度模式中，重力波阻力的参数化中的错误被认为是扩展范围预测中的主要误差源。 在先前有关该主题的研究的研究下，首席研究者发现，垂直传播的山波似乎不像以前认为的那样对基础地形的不对称性敏感。 使用自由滑动条件，他发现最大的Lee斜率风也不对地形的不对称性敏感。 但是，当包括表面摩擦时，对地形的敏感性将增强，但最大风的主要调节因子似乎是Lee斜坡的陡度。 首席研究人员将继续进行这一研究，其最终目标是改善山区附近地点的天气预报，并改善扩展范围的预测和气候模型。 集中注意力的主要领域是：对复杂的三维地形中的气流进行调查，重点是有和没有山间隙的山区屏障以及孤立的山峰；研究地形强制重力波中的动量通量以及这些波的相互作用与重力波阻力的较大尺度流动。