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

鉴于估计世界六分之一以上的人口的大部分水资源来自含有季节性融雪的盆地，山区在水文方面具有重要意义。事实上，在许多半干旱地区，城市和农业地区几乎完全依靠区域山区的融雪径流。尽管这些地区具有重要意义，但区域气候模式（RCMs）对这些复杂地形地区的模拟效果往往很差。提高对复杂地形下陆地-大气相互作用的认识是提高山区rcm预测的关键一步。该项目的主要目标是研究复杂地形下的陆地-大气相互作用，重点是雪起重要作用的地区。该项目将利用2002-2003年在科罗拉多州北部进行的冷陆过程现场实验（CLPX）站点的大量数据来解决科学问题。拟议的研究将使用分层方法来调查积雪过程和一系列地理特征的耦合陆地-大气相互作用。这种方法不仅可以明确表示地表非均匀性，而且可以明确表示地表状态（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。几个科学问题将在过程理解（雪和耦合陆地-大气过程）、空间变异性（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得到解决。这项工作将推动关于山区地形过程的知识状态向前发展，并与许多相关学科交叉联系，包括雪水文学、山地气象学、边界层过程和计算流体动力学。本项目的更广泛影响源于了解山地地形中陆地-大气相互作用的重要性，以便在短期预报和气候变化分析中改进大尺度气候模式的状态和通量预测。据推测，在这个项目中获得的见解最终将被证明有助于改善山区地形大尺度模型中的亚网格尺度参数化，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.