Large-Eddy Simulation studies of Land-Atmosphere Interaction over Complex Terrain, Using New-Generation Dynamic Models

使用新一代动态模型对复杂地形上的陆地-大气相互作用进行大涡模拟研究

• 批准号: 9909679
• 负责人: Marc Parlange
• 金额: $ 31.6万
• 依托单位: Johns Hopkins University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-02-15 至 2003-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9909679&HistoricalAwards=false
• 关键词: Large; Eddy; Simulation; studies; Land

9909679Parlange Similarity theory of the atmospheric boundary layer (ABL) is the main practical approach in hydrology to obtain regional-scale evaporation. The theory is based on a uniform land surface, yet it has been found to work in field studies over heterogeneous natural land surfaces due to the turbulent flow in the ABL, which efficiently blends the various sources and inhomogeneities across the landscape. It is not well understood how internal boundary layers formed over various patches on the land surface are blended in the ABL and what surface and boundary layer features are critical to controlling ABL dynamics and structure. Large eddy simulations (LESs) of turbulent flow and transport in the ABL will be conducted over heterogeneous sources of heat and water vapor to identify the blending properties of turbulent mixing under various conditions of stratification. Heterogeneous roughness properties will also be considered. Numerical simulations will employ and adapt new-generation subgrid-scale models that are particularly well suited to capture unresolved small-scale turbulence physics in complex environments in which turbulence deviates from the classical assumptions of isotropic inertial-range behavior. The models are based on a combination of (a) the dynamic procedure which eliminates the need to specify tunable model coefficients, (b) a generalization of the dynamic model to account for scale dependence of the coefficients for applications outside of the inertial range of turbulence such as the near-ground dynamics of the ABL, (c) the Lagrangian averaging method, which allows applications of the dynamic model to spatially non-homogeneous flow conditions, and (d) the mixed similarity or nonlinear model, which provides more realistic descriptions of subgrid-scale processes, including reverse cascade of kinetic energy and scalar variance, and the relationship between coherent structures and subgrid-scale fluxes and dissipation. High-resolution LES will be conducted to identify the role of land surface scale on atmospheric dynamics and transport. The results will first be compared with well-known field observations over statistically homogeneous land surfaces and extended to more general land surface patterns and stability conditions. Through a series of simulations, where surface humidity, temperature, roughness and geometric arrangements are varied systematically, we will quantify those features which drive the dynamics of land-atmosphere exchange over heterogeneous terrain. Ultimately, this information will be used in new strategies for obtaining regional-scale evaporation over complex terrain

Parlange大气边界层相似理论是水文学中获取区域尺度蒸发量的主要实用方法。 该理论是基于一个统一的土地表面，但它已被发现工作在现场研究的异质性自然土地表面由于湍流的ABL，有效地融合了各种来源和景观的不均匀性。 目前还不清楚如何在陆地表面上的各种补丁形成的内部边界层混合在ABL和什么样的表面和边界层功能是至关重要的控制ABL的动力学和结构。 将在热量和水蒸气的异质源上对大气边界层中的湍流和输送进行大涡模拟，以确定各种分层条件下湍流混合的混合特性。 还将考虑不均匀粗糙度特性。 数值模拟将采用和调整新一代亚网格尺度模型，这些模型特别适合于在湍流偏离各向同性惯性范围行为的经典假设的复杂环境中捕获未解决的小尺度湍流物理。 这些模型是基于以下几个方面的组合：（a）动力学过程，它消除了指定可调模型系数的需要，（B）动力学模型的一般化，以说明在湍流惯性范围之外的应用（如ABL的近地面动力学）中系数的尺度依赖性，（c）拉格朗日平均法，该模型允许将动态模型应用于空间非均匀流动条件，以及（d）混合相似性或非线性模型，该模型提供亚网格尺度的更真实的描述 过程，包括动能和标量方差的反向级联，以及相干结构和次网格尺度通量和耗散之间的关系。 将进行高分辨率LES以确定陆面尺度对大气动力学和输送的作用。 结果将首先进行比较，在统计均匀的土地表面和扩展到更一般的土地表面模式和稳定性条件下，与众所周知的实地观察。 通过一系列的模拟，其中表面湿度，温度，粗糙度和几何布置系统地变化，我们将量化这些功能，驱动在异质地形的陆-气交换的动态。 最终，这些信息将用于获得复杂地形上区域尺度蒸发的新策略