CAREER: Effect of Land-Surface Heterogeneity on Regional-Scale Fluxes Using a New Generation Large-Eddy Simulation

对区域尺度热量和水蒸气通量的测量和预测(从水文、天气和气候模型)会受到重大误差的影响，这与我们理解和解释地表变化的影响的能力有限有关。例如，数值天气模式使用基于相似理论的边界条件，该理论假设地表是均匀的，而忽略了次网格尺度的可变性。这项研究通过风洞实验、遥感现场测量和三维瞬变数值模拟(大涡模拟)的新组合，提高了我们对陆地-地表不均匀和大气湍流之间复杂的双向耦合的理解，从而解决了这些限制。风洞实验研究控制瞬时表面特征(剪应力)和空气流动特性(风速)之间的关系的物理，以开发物理上更真实的边界条件。新一代大涡模拟将包括改进的边界条件以及新的亚网格尺度湍流。将使用风洞实验和遥感现场测量来评估非均匀表面上边界层的性能。该模式用于研究地表变率如何向上传播并影响大气边界层。这些结果有望大大提高我们对陆地-大气交换过程进行参数化的能力，从而提高水文、天气和气候模型的准确性。教育创新是：(1)开发一种新的教育工具，利用LES的潜力来提供陆地表面上方湍流的三维瞬时信息。(2)开发和巩固课程，以纳入我们研究背后的动机和基本思想，因为它们达到了教学上的成熟。(3)在最先进的实验、数值和理论方法之间的耦合和反馈的基础上，指导和吸引博士、硕士和本科生进行跨学科研究。(4)通过为高中教师和学生举办研讨会，特别强调来自传统上在科学和工程领域代表性较低的群体的学生。

0094200Porte-AgelMeasurement and prediction (from hydrologic, weather and climate model) of regional-scale fluxes of heat and water vapor are subject to substantital errors associated with our limited ability to understand and account for the effect of land-surface variability. For example, numerical weather models use boundary conditions based on similarity theory, which assumes homogeneity of the land surface and ignores subgrid-scale variability. This study addresses these limitations by advancing our understanding of the complex two-way coupling between land-surface heterogeneity and atmospheric turbulence through a novel combination of wind tunnel experiments, remote-sensing field measurements, and three-dimensional transient numerical simulations (large-eddy simulations). The wind tunnel experiments study the physics governing the relationship between instantaneous surface characteristics (shear stress) and air flow properties (wind velocity) in order to develop physically more realistic boundary conditions. A new generation LES will be developed to incorporate the improved boundary conditions, as well as new subgrid-scale turbulence. Performance for boundary layers over heterogeneous surfaces will be evaluated using wind tunnel experiments and field measurements from remote sensing. The model is used to study how land-surface variability propagates upwards and affects the atmospheric boundary layer. These results are expected to substantially improve our ability to parameterize land-atmosphere exchange processes and, consequently, the accuracy of hydrologic, weather and climate models.The education innovations are to:(1) Develop a new education tool that exploits the potential of LES to provide 3-D transient information of the turbulent flow above the land surface.(2) Develop and solidify curriculum to incorporate the motivation and fundamental ideas behind our research as they achieve pedagogical maturity. (3) Mentor and engage Ph.D, M.S., and undergraduate students in interdisciplinary research based on the coupling and feedback between the state-of-the-art experimental, numerical, and theoretical approaches.(4) Outreach through workshops for high school teachers and students, with special emphasis on students from groups traditionally underrepresented in science and engineering.