Orographic Precipitation and Regional Climates

地形降水和区域气候

• 批准号: 0930356
• 负责人: Ronald Smith
• 金额: $ 70.63万
• 依托单位: Yale University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-06-15 至 2014-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0930356&HistoricalAwards=false
• 关键词: Orographic; Precipitation; Regional; Climates

Orographic precipitation, which depends profoundly on the interaction of airflow with underlying mountainous terrain, has received considerable attention though large and complex field programs. This project seeks to evaluate novel theoretical constructs in the context of comparatively simple terrain forcing. The main hypothesis to be explored is that orographic precipitation in the tropics may be described as "ascent-forced" convection, in which terrain plays a key role in modulating not only upstream triggering of new convective clouds, but their entire life cycle along trajectories across a given mountain barrier. While cordilleras at various latitudes will ultimately be examined, intensive observations will first be conducted by the NSF-supported University of Wyoming King Air research aircraft operating over/around the Caribbean Island of Dominica. During the DOMinica EXperiment (DOMEX) in March-April 2011, the King Air's in situ and cloud radar/lidar King Air measurement capabilities will be combined with data from ground-based weather radar and networked rain gauges to comprehensively describe clouds and precipitation that form when comparatively steady trade-wind flow impacts an isolated mountain ridge. These measurements will specify the nature of this convection, including its relationship to the existence and magnitude of upstream moisture and temperature fluctuations, and better describe cloud dynamics and microphysics in terms of entrainment, vertical velocity, and cloud water production. A second focus will be to determine the applicability of these results to other locations and climate zones, with candidate comparison sites including Patagonia, Costa Rica, and southeastern Alaska. Adjunct studies will evaluate stable isotope analysis of runoff water as a straightforward means of determining the average "Drying Ratio"--the ratio of precipitation to the total water vapor flux across a mountain ridge, known to vary from near 0% in certain tropical locations to 50% at higher latitudes.The Intellectual Merit of this work centers on development of improved means to explore and describe a newly hypothesized "ascent-forced" atmospheric convection, and to better relate its occurrence to differing climate zones and associated airmass modifications for flow trajectories across both isolated and more complex arrangements of mountain ridges.Broader Impacts of this research will include mentoring and field-site training of a postdoc and graduate/undergrad students pursuing work spanning several scientific disciplines, as well as extensive international cooperation. Ultimate impacts could include improved weather and climate modeling, isotope-climate interpretation, and water resources management.

地形降水在很大程度上取决于气流与下方山区地形的相互作用，通过大型而复杂的实地项目受到了相当多的关注。 该项目旨在在相对简单的地形强迫背景下评估新颖的理论结构。 要探索的主要假设是，热带地区的地形降水可以被描述为“强制上升”对流，其中地形不仅在调节上游新对流云的触发方面发挥着关键作用，而且在调节它们沿着穿过给定山脉屏障的轨迹的整个生命周期方面发挥着关键作用。 虽然最终将检查不同纬度的山脉，但密集观测将首先由美国国家科学基金会支持的怀俄明大学国王航空研究飞机在多米尼加加勒比岛上空/周围进行。 在2011年3月至4月的多米尼加实验（DOMEX）期间，空中国王的原位和云雷达/激光雷达测量能力将与地面天气雷达和联网雨量计的数据相结合，以全面描述相对稳定的信风流冲击孤立山脊时形成的云和降水。 这些测量将明确这种对流的性质，包括其与上游水分和温度波动的存在和大小的关系，并更好地描述云动力学和夹带、垂直速度和云水产生方面的微物理。 第二个重点是确定这些结果对其他地点和气候带的适用性，候选比较地点包括巴塔哥尼亚、哥斯达黎加和阿拉斯加东南部。 辅助研究将评估径流水的稳定同位素分析，作为确定平均“干燥比”的直接方法，即降水量与山脊总水蒸气通量的比率，已知其变化范围从某些热带地区的接近 0% 到高纬度地区的 50%。这项工作的智力价值集中在开发改进的方法来探索和描述新假设的“强迫上升”大气 对流的发生，并更好地将其发生与不同的气候带以及相关的气团变化联系起来，以穿过孤立的和更复杂的山脊布置的流动轨迹。这项研究的更广泛影响将包括对从事跨多个科学学科工作的博士后和研究生/本科生的指导和现场培训，以及广泛的国际合作。 最终影响可能包括改进天气和气候模型、同位素气候解释和水资源管理。