Turbulent fluxes and thermal convection in a valley

山谷中的湍流和热对流

• 批准号: 175584344
• 负责人: Professor Dr. Thomas Foken
• 金额: --
• 依托单位: Department Troposphärenforschung (IMK-TRO)
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2010
• 资助国家: 德国
• 起止时间: 2009-12-31 至 2011-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/175584344?language=en
• 关键词: Turbulent; fluxes; thermal; convection; valley

The proposed project is the 3rd year extension of a running project, which investigates the development of boundary layer convection in the Kinzig valley (center Black Forest) with the help of surface energy exchange measurements of the COPS experiment combined with large-eddy simulations (LES). Preliminary work was done setting up a quality controlled data base of surface turbulent flux measurements and checking the energy balance closure of all flux sites. In the Kinzig valley, relevant days with situations of free convection initiated near the ground were selected, which serve as a base for further LES studies. A LES model was adapted to the heterogeneous landscape of the Kinzig valley and idealized model runs with complex topography and heterogeneous forcing by heat fluxes at the lower boundary were carried out. Based on this preliminary work, the 3rd year extension will allow us to concentrate on the simulation of some selected free convection situations and test their sensitivity to surface inhomogeneities and orographic details and investigate their impact on the thermodynamic structure of the boundary layer. Moreover, the spatial and temporal scales of the convective events will be studied with ogive, spectral and wavelet analysis methods. An attempt to close the surface energy balance equation with the help of “virtual towers“ within the model domain will be made by considering flux contributions of secondary circulations, which develop over heterogeneous terrain and are not captured by stationary fixed-point turbulence measurements. This will lead to a correction of the flux measurements dependent on the flux contributions of the secondary circulations.

拟议的项目是一个正在进行的项目的第三年扩展，该项目利用COPS实验的表面能量交换测量结合大涡模拟（LES）研究Kinzig山谷（黑森林中心）边界层对流的发展。初步工作是建立一个质量控制的数据库，表面湍流通量测量和检查能量平衡关闭的所有通量网站。在Kinzig山谷，选择了与近地面开始的自由对流情况相关的天数，作为进一步LES研究的基础。一个LES模式适应的异质景观的Kinzig山谷和理想化的模式运行复杂的地形和异质强迫热通量在下边界进行。在这项初步工作的基础上，第三年的延期将使我们能够集中精力模拟一些选定的自由对流情况，测试它们对表面不均匀性和地形细节的敏感性，并研究它们对边界层热力学结构的影响。此外，还将用尖拱、谱和小波分析方法研究对流事件的时空尺度。试图关闭表面能量平衡方程的帮助下，“虚拟塔”的模式域中，将考虑通量的二次环流的贡献，发展在非均匀地形和固定的定点湍流测量不捕获。这将导致依赖于二次环流的通量贡献的通量测量的校正。