Mesoscale Modeling of Precipitation in Coastal Regions of Complex Orography

9612876 Mass美国天气研究计划（USWRP）是一项跨部门活动，旨在执行和实施必要的研究，以改善向全国提供的天气服务。根据该计划，美国国家科学基金会和国家海洋和大气管理局（NOAA）将共同评估和支持USWRP高度优先的天气研究。北美西海岸降水分布受该地区地形影响较大，形成了山脉迎风面增强和背风面降水阴影的复杂格局。最近，加利福尼亚北部和太平洋西北地区发生的一系列重大洪水事件，造成了数十亿美元的损失和数人死亡，突显了地形对沿海地区降水的调节作用的重要性。本提案的目的是评估高分辨率区域大气模型在诊断和预测西北山区沿海地区地形调节降水方面的潜力美国。虽然目前的业务天气预报模式缺乏正确预报地形降水的分辨率，但越来越多的区域模式模拟表明，有了足够的分辨率，可以在复杂地形的沿海地区真实地预测降水。如果成功，高分辨率建模将提供更好的降水预报，并将其输出与水文模型相结合，可以更准确地预测河流流量、河流阶段和洪水。这项研究工作将评估一个高分辨率中尺度模式在北美地形西海岸一系列强降水/洪水事件中的表现。作为评估的一部分，将进行实验，以确定为沿海降水/洪水事件产生最佳区域模式性能所需的分辨率、模式物理和数据同化方法。该模式将实时运行，以评估模式在中等（~10-15公里）分辨率下的长期降水技能，并在非常高分辨率（低至1-3公里水平分辨率）下进行一系列回顾性案例研究。这些案例研究将包括加利福尼亚和太平洋西北部的强降水/洪水事件，以及阿拉斯加东南部的至少一个案例。除了评估和提高高分辨率大气模型预测地形降水的能力外，这项工作还将涉及将模型的降水、温度和风场与流域水文模型相结合。这种模式耦合有可能大大改善河流高度和洪水的短期预报。最后，该项目将促进华盛顿大学科学家与美国国家气象局在加利福尼亚、俄勒冈、华盛顿和阿拉斯加的预报办公室之间的积极互动。＊＊＊

9612876 Mass The U.S. Weather Research Program (USWRP) is an interagency activity designed to perform and implement the research necessary to improve the delivery of weather services to the nation. Under this Program, the National Science Foundation and the National Oceanic and Atmospheric Administration (NOAA) are jointly evaluating and supporting weather research of high priority to the USWRP. The distribution of precipitation along the west coast of North America is greatly influenced by the orography of the region, resulting in a complex pattern of enhancement on the windward sides of mountains and precipitation shadows to their lee. The importance of orographic modulation of coastal zone precipitation has been highlighted recently by a series of major flooding events in northern California and the Pacific Northwest that have resulted in losses in the billions of dollars and several deaths The objective of this proposal is to evaluate the potential of high-resolution regional atmospheric models for diagnosing and predicting orographically modulated precipitation along the mountainous coastal zone of western North America. Although current operational weather prediction models lack the resolution to correctly forecast orographic precipitation, a growing collection of regional model simulations suggests that with sufficient resolution, precipitation can be predicted realistically in coastal regions of complex terrain. If successful, high resolution modeling would offer improved precipitation forecasts and coupling their output to hydrological models could lead to more accurate prediction of stream flow, river stages, and flooding. This research effort will evaluate the performance of a high-resolution mesoscale model for a range of heavy precipitation/flooding events along the orographic west coast of North America. As part of this evaluation, experiments will be made to determine the resolution, model physics, and data assimilation methods r equired for producing the best possible regional model performance for coastal precipitation/flooding events. The model will be run both in real time to evaluate the long-term precipitation skill of the model at moderate (~10-15 km) resolution and for a series of retrospective case studies at very high resolution (down to 1-3 km horizontal resolution). These case studies will include California and Pacific Northwest heavy precipitation/flooding events and at least one case for southeastern Alaska. In addition to evaluating and improving the ability of high resolution atmospheric models to forecast orographic precipitation, this effort will also involve interfacing the model's precipitation, temperature, and wind fields with a watershed hydrological model. Such model coupling has the potential to greatly improve short- term forecasts of river height and flooding. Finally, this project will promote active interaction between the University of Washington scientists and National Weather Service forecasts offices in California, Oregon, Washington, and Alaska. ***