Stefanie Kiemle is doctoral researcher at the Department of Hydromechanics and Modelling of Hydrosystems and member of the research training group integrated in SFB 1313 "Interface-Driven Multi-Field Processes in Porous Media". On Wednesday 19th April 2023 at 16:00 pm, she will give her milestone-presentation entitled "Analysis of Evaporation Processes at the Land Surface - Atmosphere Interface".
Date: Wednesday, 19th April 2023
Time: 16:00 pm CET
Title: "Analysis of Evaporation Processes at the Land Surface - Atmosphere Interface"
Place: Pfaffenwaldring 61, U1.003 (MML)
Abstract
Evaporation from land surfaces plays a crucial role in both the water balance and the land surface energy balance. Understanding the interaction processes across the soil-atmosphere interfaces is one key aspect in predicting climate change as many environmental issues such as soil salinization or greenhouse gas migration from the subsurface are driven by evaporation. With the help of numerical models, we can enhance our understanding of the complex physical processes and transport mechanisms that occurs when water evaporates from soils into the atmosphere. One aspect of evaporation from soils is the propagation of the evaporation front in soils. Using the phenomena of evaporation-driven fractionation of stable water isotopologues, which are natural tracers, the evaporation front can be identified. To describe the fractionation of the stable water isotopologues in our numerical models, we implemented well-known parameterizations which describe the fractionation but also used coupled models for the atmosphere and soils to derive the fractionation of the isotopologues. During evaporation, soils are at risk for salinization. As water evaporates from soils, salts accumulate at the evaporation front. This increase in density can lead to a net downward transport of salt and the development of concentration instabilities in the form of fingers. These density-driven instabilities can potentially avoid salt precipitation. Using a linear stability analysis and numerical simulation, the onset time and the main processes leading to the instabilities are identified for different conditions in an unsaturated porous medium.
The interaction processes between the soil surface and the atmosphere influence evaporation. Numerical models must ensure that the given atmospheric boundary conditions correctly display the transport and the mixing of components in the atmosphere. An outlook, on the analysis of different numerical models describing the atmospheric domain and an experimental setup to evaluate the atmospheric conditions on the field scale, will be presented.
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