Studies of Orographic Precipitation Processes

在这项研究中要解决的基本科学问题是使用偏振雷达信号来了解山地云系统的微物理演变，并改进在各种各样的云系统中解释偏振雷达信号的方法。 具体目标是利用中尺度阿尔卑斯方案的偏振雷达测量和通过观测验证实验改进微物理参数化（IMPROVE II）结合飞机微物理数据，解决两个关键的未解决的科学问题：第一章当云系接近和上升主要地形障碍物时，地形如何影响云系内的微物理过程和降水发展以及更精细的地形特征2)暖雨微物理学对山地云系降水过程的作用是什么？ 实现这些科学目标的基础是从地形云系统的偏振测量中定量解释粒子类型。 这项研究的知识价值在于它将提供关于山脉在增加降水方面的作用的新认识。 该研究还将探索解释偏振雷达测量结果的新方法。 虽然过去的地形云系统的研究已被限制为目标的机会时，飞机数据或垂直指向的遥感器可用，这项研究将利用四维偏振雷达覆盖范围，允许检查在更精细的细节微物理过程的关系，不断变化的云结构上游和山脉。 结果也将有应用到非地形系统的微物理过程与距离的过渡是不突然的。拟议研究的广泛影响是重大的。 拟议的研究与山区水资源的有效管理直接相关，因为偏振雷达将在未来在美国和国际上用于测量降水。 这项研究将直接有助于了解欧洲阿尔卑斯山和俄勒冈州瀑布的降水过程。 在这两个地区，水资源与地形降水密切相关。 预测模型开发人员将利用这项研究的结果来评估降水参数化，并改善山区降水的预测。 这一点很重要，因为准确预测降水量可以减少经常造成灾难性洪水的频繁强降水事件的经济影响。 该研究还将导致更好地解释偏振雷达数据，这将在美国和其他国家都很重要，因为偏振雷达已经投入使用，预报员和公众可以使用产品。

The fundamental scientific problem to be addressed in this research is to use polarization radar signatures to understand the microphysical evolution of mountain cloud systems, and improve methodologies for interpreting polarization radar signatures in a wide variety of cloud systems. The specific objectives are to use polarization radar measurements from the Mesoscale Alpine Programme (MAP) and the Improvement of Microphysical Parameterization through Observational Verification Experiment (IMPROVE II) in conjunction with aircraft microphysical data to address two key unresolved scientific questions: 1) How does topography affect microphysical processes and precipitation development within cloud systems as they approach and ascend major topographic barriers and finer scale topographic features? 2) What is the role of warm rain microphysics on precipitation processes in mountain cloud systems? Fundamental to achieving these scientific objectives is the quantitative interpretation of particle types from polarization measurements in orographic cloud systems. The intellectual merit of the research has its basis in the new understanding it will provide concerning the role of mountains in enhancing precipitation. The research also will explore novel ways to interpret measurements from polarization radars. While past studies of orographic cloud systems have been restricted to targets of opportunity when aircraft data or vertically pointing remote sensors were available, this study will take advantage of four dimensional polarization radar coverage, allowing examination in much finer detail of the relationship of microphysical processes to evolving cloud structures both upstream and over the mountain ranges. The results will also have application to non orographic systems where the transitions in microphysical processes with distance are not as abrupt. The broader impacts of the proposed research are significant. The proposed research has direct relevance to the effective management of water resources in mountainous regions, since polarization radars will be used in the future in the United States and internationally, to measure precipitation. The research will contribute directly toward understanding precipitation processes over the European Alps and the Oregon Cascades. In both these regions, water resources are closely tied to orographic precipitation. Forecast model developers will use the results of this research to evaluate precipitation parameterizations and improve the prediction of precipitation in mountainous regions. This is important since accurate prediction of precipitation can reduce the economic impacts of frequent heavy precipitation events that often produce catastrophic floods. The research will also lead to a better interpretation of polarization radar data, which will be important both in the United States and in other countries as polarization radars become operational and products become available to forecasters and the public.