Orographic Precipitation and Airmass Transformation

提高对地形降水和气团干燥的了解和模拟能力将有助于解决一些地球科学问题，包括：山洪预报、水资源、山地冰川、冰芯解释、侵蚀、雨影沙漠和海洋间水运。目前大多数模型要么过于简化，要么无法解决关键的湿润地形流动过程。在这项研究中，首席研究员将测试现有的中尺度模型，并结合气流动力学和微物理学发展新的理论。最优先的是将现有模式运行与中尺度高山计划（MAP）的数据进行比较。这是唯一使用新技术的详细数据集，可以诊断主要山脉上的湿空气流动。已确定4例MAP病例具有不同的特征。对于每种情况，三个数值模型的输出将与常规和飞机数据进行比较。如果协议令人满意，将对输出进行详细解释。几个理论问题将在分析中解决：湿上升与流动分裂和阻塞的相对作用；触发对流;包裹轨迹的精度；模型分辨率的影响；降水效率“阈值”理论的检验对微物理算法的敏感性；以及混合流的等效位温守恒。研究的第二阶段将包括由其他小组管理的三个当代中等规模实验的数据和出版物。将对这些项目的结果进行比较，以便将MAP的结果置于更广泛的背景下，并作出谨慎的概括。在项目的最后阶段，将进行相关地形降水模式在其他地球科学学科中的应用（见上述项目），扩大工作的影响。将尝试对该领域进行学术调查。从这一研究活动中可以看出对教育项目的重大影响。本科生、研究生和博士后将参与实地工作和数据分析。

An improved understanding of, and the ability to model, orographic precipitation and air mass drying would contribute to solving a number of earth science problems involving: flash flood prediction, water resources, mountain glaciers, ice core interpretation, erosion, rain-shadow deserts and inter-ocean water transport. Most current models either oversimplify or fail to resolve key moist orographic flow processes. In this research, the Principal Investigator will test existing mesoscale models and develop new theories combining airflow dynamics and microphysics.The highest priority is to compare existing model runs with data from the Mesoscale Alpine Programme (MAP). This is the only detailed data set using new technologies that allows moist air flow over a major mountain range to be diagnosed. Four MAP cases have been identified with differing characteristics. For each case, output from three numerical models will be compared with conventional and aircraft data. If the agreement is satisfactory, detailed interpretation of the output will follow. Several theoretical questions will be addressed in the analysis: the relative role of moist ascent versus flow splitting and blocking; triggered convection; the accuracy of parcel trajectories; the effect of model resolution; the testing of the "threshold" theory of precipitation efficiency; sensitivity to microphysical algorithms; and the conservation of equivalent potential temperature in mixing flows. The second phase of the research will include data and publications from three contemporary medium scale experiments managed by other groups. The results from these projects will be compared to put the MAP results into a broader context and allow cautious generalizations to be developed.In the final phase of the project, applications of relevant orographic precipitation models to other geoscience disciplines (see items above) will be undertaken, broadening the impact of the work. A scholarly survey of the field will be attempted. Considerable influence on educational programs should be seen from this research activity. Undergraduate and graduate students and post-docs will be involved in the field work and data analysis.