Effect of Spatial Organization of Surface Properties on Land-Atmosphere Fluxes using a New Generation Large-Eddy Simulation

0537856 porte - agel利用水文、天气和气候模式对动量、热量和水汽的区域通量进行预测，由于我们解释陆地表面变率和大气不稳定的综合影响的能力有限，存在很大的误差。为了进一步认识地表非均质性与大气边界层之间的复杂耦合关系，提出了风洞实验与大涡模拟（LES）结合遥感地表条件的新方法。首先，将创建一个框架来评估新一代LES在异质表面上的性能（包括最近在无调谐动态亚网格尺度模型方面的进展）。这将通过风洞实验和1997年南方大平原（SGP-97）水文实验期间获得的实地测量来实现。将特别强调研究最近开发的无调谐动态亚网格尺度参数化的能力，以一致地调整与表面粗糙度和温度变化相关的流动不均匀性和各向异性。我们还将使用合成随机替代场来研究表面性质（气动粗糙度、温度和湿度）的空间组织对湍流通量的大小和分布的影响。此外，我们的研究结果将用于评估常规相似理论和地表非均质参数化在业务预测模型中的局限性。将提出基于物理的相似性理论修正，以包括表面性质的空间自相关和相互相关结构的影响。拟议的研究有望提高我们模拟陆地-大气交换过程的能力，从而提高水文、天气和气候模型的准确性。虽然大尺度数值模式在过去几年中取得了实质性的改进，但仍然存在一个主要挑战，即在比数值模式分辨率小的尺度上解释陆地表面性质（温度、粗糙度、湿度）的非均质性的影响。我们预计我们的研究将提出计算效率高且具有物理吸引力的子网格参数化，以便它们可以用于业务预测模型。此外，将开发一种新的基于网络的教育工具，以利用高分辨率模拟大气边界层湍流传输的可视化/动画的教育潜力。新工具将用于本科和研究生课程，以及高中生的外展活动。此外，两名研究生将接受培训，并将参与制订和执行教育工具。

0537856Porte-AgelPrediction of regional fluxes of momentum, heat and water vapor using hydrologic, weather and climate models is subject to substantial errors associated with our limited ability to account for the combined effects of land surface variability and atmospheric instability. A novel combination of wind tunnel experiments and large-eddy simulations (LES) coupled with remotely-sensed surface conditions is proposed to advance our understanding of the complex coupling between land surface heterogeneity and the atmospheric boundary layer. First, a framework will be created to evaluate the performance of the new generation LES (including recent advances in tuning-free dynamic subgrid-scale models) over heterogeneous surfaces. This will be achieved through wind tunnel experiments as well as field measurements obtained during the Southern Great Plains 1997 (SGP-97) Hydrology Experiment. Special emphasis will be placed on studying the ability of the recently developed tuning-free dynamic subgrid-scale parameterizations to consistently adjust to the flow inhomogeneity and anisotropy associated with changes in surface roughness and temperature. We will also use synthetic stochastic surrogate fields to study the effect of spatial organization of the surface properties (aerodynamic roughness, temperature and moisture) on the magnitude and distribution of the turbulent fluxes. Furthermore, our results will be used to assess the limits of conventional similarity theory and surface heterogeneity parameterizations used in operational forecast models. Physically-based modifications of similarity theory will be proposed to include the effects of the spatial autocorrelation and cross-correlation structure of surface properties.The proposed research is expected to improve our ability to model land-atmosphere exchange processes and, as a result, the accuracy of hydrologic, weather and climate models. Although substantial improvements of large-scale numerical models have been achieved over the last several years, a major challenge still remains to account for the effects of heterogeneity of land-surface properties (temperature, roughness, moisture) at scales smaller than the resolution of the numerical models. We anticipate that our research will propose sub-grid parameterizations that are computationally efficient and physically attractive such that they can be used in operational forecast models. In addition, a new web-based educational tool will be developed to take advantage of the educational potential of visualizations/animations of high-resolution simulations of turbulent transport in the atmospheric boundary layer. The new tool will be used in undergraduate and graduate courses as well as outreach activities for high school students. Furthermore, two graduate students will receive training and will also participate in the elaboration and implementation of the educational tool.