Investigation of diurnal land-atmosphere interactions in snow-dominated mountainous terrain

山区具有重要的水文意义，因为据估计，世界上超过六分之一的人口的大部分水资源来自含有季节性融雪的盆地。事实上，在许多半干旱地区，城市和农业地区几乎完全依赖区域山区的融雪径流。尽管它们很重要，但使用区域气候模型(RCM)对这些地形复杂的地区的模拟往往很差。提高对复杂地形中陆气相互作用的认识是提高山地RCM预报精度的关键一步。本项目的主要目标是研究复杂地形中的陆气相互作用，重点是雪起重要作用的地区。该项目将利用在科罗拉多州北部(2002-2003年)进行的寒冷陆地过程实地实验(CLPX)现场提供的大量数据来解决科学问题。这项拟议的研究将使用分层方法来研究一系列地形特征中的降雪过程和耦合的陆地-大气相互作用。这种方法将允许不仅在地形上，而且在地面状态(例如，雪、反照率)、辐射通量和湍流通量以及它们对三维边界层流动和云形成的影响中明确地表示地表的非均质性。将在过程理解(雪和陆地-大气耦合过程)、空间可变性(作为地形的函数)及其如何影响陆地-大气相互作用、地表状态/通量的不确定性以及这种不确定性如何在耦合系统内传播等领域处理若干科学问题。这项工作将推动关于山区地形过程的知识状况向前发展，交叉连接到许多相关学科，包括雪水文学、山区气象学、边界层过程和计算流体动力学。该项目的更广泛影响源于了解山区陆地-大气相互作用的重要性，以便在近期预报和气候变化分析中改进对大规模气候模式中状态和通量的预测。假设在这个项目中获得的洞察力最终将被证明是有益的，在山区地形的大尺度模型中改进亚网格尺度的参数化，这将对研究界的广泛群体有用。

Mountain regions are hydrologically important given the estimate that over one-sixth of the world's population derive the majority of their water resources from basins containing seasonal snowmelt. In fact, in many semi-arid regions, urban and agricultural areas rely almost exclusively on snowmelt runoff from regional mountainous areas. Despite their importance, these regions of complex terrain are often poorly simulated using regional climate models (RCMs). Improvement in understanding land-atmosphere interactions in complex terrain is a key step toward improving the predictions of RCMs in montane regions.The primary objective of this project is to study land-atmosphere interactions in complex terrain with an emphasis on those areas where snow plays a significant role. The project will address science questions using the wealth of data from the Cold Land Processes Field Experiment (CLPX) site that took place in northern Colorado (2002-2003). The proposed research will use a hierarchical approach to investigate snow process and coupled land-atmosphere interactions across a range of physiographic characteristics. Such an approach will allow for explicit representation of surface heterogeneity in not only topography, but in surface states (e.g., snow, albedo), radiative fluxes, and turbulent fluxes, as well as their impacts on 3D boundary layer flow and cloud formation. Several science questions will be addressed in the areas of process understanding (both snow and coupled land-atmosphere processes), spatial variability (as a function of physiography) and how it impacts land-atmosphere interactions, and uncertainty in surface states/fluxes and how this uncertainty propagates within the coupled system. This work will move the state of knowledge regarding processes in mountainous terrain forward with cross-connections to many related disciplines including snow hydrology, mountain meteorology, boundary-layer processes, and computational fluid dynamics.The broader impacts of this project derive from the importance of understanding land-atmosphere interactions in mountainous terrain in order to yield improved predictions of states and fluxes in large-scale climate models, both for near-term forecasts and climate change analysis. It is hypothesized that the insight gained in this project will ultimately prove useful for improving sub-grid scale parameterizations in large-scale models in mountainous terrain, which would be useful to a broad group in the research community.