COLLABORATIVE RESEARCH: The Role of Canopy Structure on Variability of Water and Heat Fluxes from Forested Watersheds

合作研究：冠层结构对森林流域水和热通量变化的作用

• 批准号: 9903471
• 负责人: Gabriel Katul
• 金额: $ 14.39万
• 依托单位: Duke University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-09-01 至 2002-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9903471&HistoricalAwards=false
• 关键词: COLLABORATIVE; RESEARCH; Role; Canopy; Structure

9903471 KatulThis study investigates the exchange of water vapor, energy, and momentum between forested watersheds and the atmospheric boundary layer (ABL), using a combination of emerging tools in numerical simulation of turbulent flow and transport through and above plant canopies and recent result from a comprehensive field campaign. The field experiment, conducted in October of 1997, included seven research groups measuring land surface fluxes of water vapor, heat, carbon dioxide, and momentum on seven towers situated within a pine forest at Duke Forest near Durham, North Carolina. The data set studied here is the first comprehensive experiment that includes simultaneous velocity statistics and flux measurements at as many as seven locations in the canopy sublayer of a forest along with detailed leaf area density profile measurements in space. To explore and generalize the relationship between forest structure and observed heat and water vapor fluxes, an investigation using three-dimensional Large Eddy Simulations (LES) is proposed. These simulations are the first to explicitly consider variability in leaf area density in space and employ radiative transfer schemes to realistically account for energy attenuation by foliage elements. The simulations, which treat the foliage as a multiply-connected porous medium, will permit investigating how the spatial structure of forest canopies interact with energy/radiation and the turbulent transport dynamics to give rise to the observed spatial patterns in land surface flux fields within and above the canopy. An anticipated result is an understanding of what spatial variability in fluxes could be attributed to spatial variability in canopy structure for flux measurements within the canopy sublayer. The results from this study will guide future field experiments that seek to estimate forest-wide average fluxes from tower measurement and will rigorously assess the range of applicability of one-dimensional canopy models.

9903471 Katul 这项研究研究了森林流域和大气边界层 (ABL) 之间的水蒸气、能量和动量的交换，结合使用了湍流数值模拟中的新兴工具和植物冠层上方的输送以及最近的结果全面的实地宣传活动。 这项现场实验于 1997 年 10 月进行，七个研究小组测量了北卡罗来纳州达勒姆附近杜克森林松树林内七座塔的水蒸气、热量、二氧化碳和动量的地表通量。 这里研究的数据集是第一个综合实验，其中包括森林冠层亚层中多达七个位置的同步速度统计和通量测量，以及空间中详细的叶面积密度剖面测量。 为了探索和概括森林结构与观测到的热量和水蒸气通量之间的关系，提出了使用三维大涡模拟（LES）进行研究。 这些模拟首次明确考虑了空间中叶面积密度的变化，并采用辐射传输方案来实际解释叶子元素的能量衰减。 这些模拟将树叶视为多重连接的多孔介质，将允许研究森林冠层的空间结构如何与能量/辐射和湍流传输动力学相互作用，从而产生在陆地表面通量场中观察到的空间模式树冠上方。 预期的结果是了解通量的空间变异性可以归因于冠层结构的空间变异性，以进行冠层子层内的通量测量。 这项研究的结果将指导未来的实地实验，这些实验旨在通过塔测量来估计整个森林的平均通量，并将严格评估一维冠层模型的适用范围。