Using mesoscale climate simulations to reduce input data errors in energy balance snow hydrology models

项目摘要本奖项是根据2009年美国复苏与再投资法案（公法111-5）资助的。高山融雪是世界上40%人口的重要资源？但受到气候变化带来的气候变暖的威胁。对于流域影响分析、地方和区域规划过程以及水政策的制定，需要对单个流域的气候敏感性进行准确的模型预测。目前，山区环境气象驱动数据集的质量是表征特定流域敏感性和利用水文模式模拟气候相关影响的主要障碍。特别是，在事件基础上准确地描述降水为雨和雪的位置，以及雪何时和多快融化，对于在小到中等（10-1000平方公里）空间尺度上评估气候敏感性至关重要。山地环境下降水、温度和辐射数据集的误差与高海拔测量的稀缺、恶劣条件导致的测量质量差、测量变量相对较少以及复杂地形下的插值误差有关。这种高度依赖尺度的误差以复杂的方式通过水文模拟模型传播。由于大多数流域的原位数据密度总是不够理想，我们建议开发和评估将基于中尺度气候模式的物理过程信息与低海拔气象站和高分辨率地形信息相结合的新方法，以便在复杂地形上更准确地重新绘制可用的气象驱动数据。目前，我们对中尺度气候模型在这一应用中的表现了解甚少，我们将利用位于加州内华达山脉的Tuolumne和北福克美国河流域的密切监测，在10至800平方公里的流域尺度上开发、评估和完善这些新技术。虽然具体的研究实验将集中在美国西部的两个山区流域，但这项研究的目的是开发和评估广泛适用于美国西部山区环境的工具，并可能在全球范围内应用。本文将解决以下研究问题：1)在不同空间尺度的积雪和融化过程模拟中，哪些强迫数据误差对水文误差贡献最大？2)如何将高分辨率气象模式的模拟与地形和有限的多尺度低海拔站数据结合起来，为复杂地形的水文模拟提供分布式强迫数据？3)中尺度气候模式用于长期水文预测时的优势和局限性是什么？整个研究将集中于对水资源的影响，研究结果将与资源管理人员分享。我们将为研究生开设一门关于水文数据收集和建模的综合课程，并将雇用本科生和研究生进行数据收集和分析。我们将与国家公园管理局的解说护林员合作，向公众宣传气候-水文联系。

Project AbstractThis award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5). Mountain snowmelt is an essential resource to 40% of the world?s population but is threatened by warming associated with climate change. Accurate model predictions of the climate sensitivity of individual watersheds are needed for watershed impacts analysis, local and regional planning processes, and the development of water policy. Currently the quality of meteorological driving data sets in mountain environments is a major obstacle to characterizing the sensitivity of particular watersheds and simulating climate related impacts using hydrologic models. In particular, accurately characterizing where precipitation falls as rain vs. snow on an event basis, and when and how fast snow melts is essential to the assessment of climate sensitivity at small to medium (10-1000 km2) spatial scales. Errors in precipitation, temperature and radiative data sets in mountain environments are related to the scarcity of high elevation measurements, poor measurement quality due to adverse conditions, relatively few measured variables, and interpolation errors in complex terrain. Such highly scale-dependent errors are propagated through hydrologic simulation models in a complex manner. Because the density of in situ data will always be less than ideal for most watersheds, we propose to develop and evaluate new methods for combining physical process-based information from meso-scale climate models with low elevation meteorological stations and high resolution topographic information to remap available meteorological driving data more accurately across complex terrain. The performance of meso-scale climate models in this application is currently poorly understood, and we will use the intensively-monitored Tuolumne and North Fork American River watersheds in the Sierra Nevada, California to develop, evaluate, and refine these new techniques at basin scales ranging from 10 to 800 km2. While specific research experiments will focus on two mountain watersheds in the western United States, the research is designed to develop and evaluate tools that will be broadly applicable in mountain environments across the western U.S. and potentially at the global scale. The following research questions will be addressed:1) What forcing data errors contribute most to hydrologic errors in the simulation of snow accumulation and melt processes at various spatial scales?2) How can simulations from high-resolution meteorological models best be combined with topography and limited low-elevation station data on multiple scales to produce distributed forcing data for hydrologic simulations in complex terrain?3) What are the strengths and limitations of meso-scale climate models when used for long-term hydrologic predictions?Throughout, the study will focus on impacts on water resources, and results will be shared with resource managers. We will develop a course on combined hydrologic data collection and modeling for UW graduate students and will employ both undergraduates and graduates in data collection and analysis. We will work with National Park Service interpretive rangers to communicate climate-hydrology connections to the general public.