How soil properties affect processes inside the soil and at the soil-atmosphere interface - interweaving experimental and modeling approaches

本研究的主要目的是分析和完善土壤-大气界面非等温、多相、多组分流动过程及其对非饱和带的影响的理论。特别着重于地表粗糙度和土壤异质性对通量的影响。总体目标是利用在不同空间和时间尺度上进行的全面计算和实验分析，开发新的、经过验证的物理和数学模型。它包含四个主要目标：1。 高保真实验室实验台和中间（2-8米长）规模将使用一个独一无二的风洞多孔介质试验设备，模拟不同的大气（例如风速、湿度、温度）、表面（例如土壤粗糙度的类型）和地下（例如土壤湿度、土壤质地和土壤结构（聚集与压实））条件以产生独特的数据集，这些数据集目前不可用。2. 将在动态室外条件下进行中等规模的实验，以（i）测试受自然非均匀性（例如土壤团聚体）和驱动力（例如风速，辐射）的昼夜动态影响的理论描述，以及（ii）确定如何最好地将非均匀性的细节包括在各个尺度上，以及它们如何影响田间尺度的交换通量。 详细的达西尺度数值模拟（如有必要，包括Forchheimer扩展），结合实验室实验的实验数据，将用于分析在传统建模工作中（例如，湍流自由流条件对通过非饱和土壤运输的影响），将自由流效应和相关的质量、动量和能量边界层结合在一起的重要性。4. 完善了土壤与大气之间的质量、动量和能量交换理论。这包括蒸发、冷凝、辐射和气体成分的传输，如挥发性有机化合物（VOC）和水稳定同位素在材料界面的存在下。作为第二步，简化模型与有效的参数，在土壤和陆地表面发生在广泛的空间和时间尺度的流动和运输过程的综合治疗的基础上，将开发，扩展和测试。

The primary objective of this research is to analyze and improve theories of non-isothermal, multi-phase, multi-component flow processes at a soil-atmosphere interface and their influence on the unsaturated zone. The special focus is on the influence of surface roughness and soil heterogeneity to the transfer fluxes. The overarching goal is to develop new, validated physical and mathematical models using comprehensive computational and experimental analyses conducted at different spatial and temporal scales. This contains 4 main objectives:1. High fidelity laboratory experiments at the bench and intermediate (2-8 m long) scale will be performed using a one-of-a-kind wind tunnel porous medium test facility, simulating different atmospheric (e.g. wind speed, humidity, temperature), surface (e.g. types of soil roughness) and subsurface (e.g. soil moisture, soil texture and soil structure (aggregated vs. compacted)) conditions to produce unique data sets, which are currently not available. 2. Intermediate scale experiments will be carried out under dynamic outdoor conditions (i) to test the theoretical descriptions affected by natural heterogeneities (e.g. soil aggregates) and diurnal dynamics of driving forces (e.g. wind speed, radiation) and (ii) to determine how details of heterogeneities can best be included across scales and how they influence exchange fluxes at the field scale.3. Detailed Darcy-scale numerical simulations (if necessary including the Forchheimer extension), in conjunction with experimental data from laboratory experiments, will be used to analyze the importance of incorporating free flow effects and the related boundary layers for mass, momentum, and energy in conventional modeling efforts (e.g. effect of turbulent free flow conditions on transport through unsaturated soils). 4. The theory of mass, momentum and energy exchange between the soil and the atmosphere will be improved. This includes evaporation, condensation, radiation, and transport of gas components such as volatile organic compounds (VOC) and water stable isotopes in the presence of material interfaces. As a second step, simplified models with effective parameters, based on an integrated treatment of the flow and transport processes occurring over a wide range of spatial and temporal scales in the soil and at the land surface, will be developed, extended, and tested.