Large-Eddy Simulation of Turbulent Atmospheric Flow within and above a Forest

PIS建议对通过森林等高大植被的冠层延伸到地表的大气表层进行标量和矢量气象场的大涡模拟。国际和平研究所已经完成并报告了这种模拟的试点研究。已在Cray Y-MP上运行的现有代码将是此项目的起点。该模型方程求解与时间相关的三维流场，考虑了树叶元素的阻力以及空气和植被之间的热交换。将进一步开发代码，以便对森林的气象学进行最佳模拟，并将根据已公布的实地观测结果，在统计特性和有组织结构的外观方面进行测试，如弹射/扫掠运动和由此产生的标量坡道和其他空间模式。计算的流场将被检查，试图将大尺度涡旋结构与在固定点的时间轨迹中观察到的信号联系起来。将进行模拟以确定森林异质性的影响，例如边缘或森林砍伐/空隙效应对计算的流场和标量场的影响。

The PIs propose to perform large-eddy simulations of the scalar and vector meteorological fields for an atmospheric surface layer extending down to the surface through the canopy layer of tall vegetation such as a forest. The PI has completed and reported a pilot study of such a simulation. The existing code, which has run on a Cray Y-MP, will be the starting point for this project. The model equations solve a time-dependent, 3-dimensional flow field with account taken for the drag of foliage elements and for heat exchange between the air and vegetation. The code will be further developed for optimal simulation of the meteorology of the forest, and output will be tested against published field observations, both in terms of statistical properties and the appearance of organized structures such as ejection/sweep motions and resultant scalar ramps and other spatial patterns. Computed flow fields will be examined in an attempt to link large-scale vorticular structures to signatures observed in time traces at fixed points. Simulations will be performed to determine the influence of forest heterogeneity, such as edge or forest clearing/gap effects on the calculated flow and scalar fields.