Orographic Precipitation and Regional Climates

地形降水在很大程度上取决于气流与下伏山地地形的相互作用，通过大型和复杂的野外项目已经得到了相当大的关注。这个项目试图在相对简单的地形强迫的背景下评估新的理论结构。要探索的主要假设是，热带地区的地形降水可能被描述为“上升强迫”对流，在这种对流中，地形不仅在上游触发新的对流云方面起着关键作用，而且在沿着给定的山障的轨迹的整个生命周期中也起着关键作用。虽然最终将对不同纬度的科迪勒拉进行检查，但密集的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月的多米尼克实验（DOMEX）期间，空中国王的现场和云雷达/激光雷达空中国王的测量能力将与地面气象雷达和联网雨量计的数据相结合，全面描述相对稳定的信风流影响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，包括它与上游湿度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微物理，包括夹带、垂直速度和云水的产生。第二个重点将是确定这些结果在其他地点和气候带的适用性，候选的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”的一种直接手段。“干燥比”是指穿过山脊的降水与总水汽通量的比率，已知在某些热带地区接近0%，在高纬度地区则为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“上升强迫”大气对流，并更好地将其发生与不同气候带和相关的气团变化联系起来，以便在孤立的和更复杂的山脊安排中流动轨迹。这项研究的更广泛影响将包括指导和实地培训博士后和研究生/本科生从事跨多个科学学科的工作，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。

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.