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、多组分流动过程的理论及其对非饱和区的影响。重点研究了地表粗糙度和土壤非均质性对迁移通量的影响。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。这包括4个主要目标：1.将使用一种独一无二的风洞多孔介质测试设备在长凳和中等(2-8米长)尺度上进行高保真实验室实验，模拟不同的大气(例如风速、湿度、温度)、地表(例如土壤粗糙度类型)和亚表层(例如土壤水分、土壤质地和土壤结构(聚集与压缩))条件，以产生目前无法获得的独特数据集。2.将在动态室外条件下进行中等尺度实验(I)以测试受自然非均质性(例如土壤团聚体)和驱动力(例如风速、辐射)的日动态影响的理论描述，以及(Ii)如何最好地包括跨尺度的非均质性细节以及它们如何影响田间尺度上的交换通量。详细的达西尺度数值模拟(如有必要，包括Forchheimer延伸)，结合实验室实验的实验数据，将被用来分析在常规模拟工作中纳入自由流动效应和相关的质量、动量和能量边界层的重要性(例如，湍流自由流动条件对非饱和土壤传输的影响)。4.完善土壤与大气的质量、动量和能量交换理论。这包括在物质界面存在的情况下，挥发性有机化合物(VOC)和水稳定同位素等气体成分的蒸发、冷凝、辐射和运输。作为第二步，将开发、推广和测试具有有效参数的简化模型，其基础是对土壤和陆地表面在广泛的空间和时间尺度上发生的流动和运输过程进行综合处理。

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.