Entwicklung und Erprobung des Hygrometer for Atmospheric Investigations

The purposse of this thesis is the development and proving of a high precision in-situ hygrometer for the research airplane $\textbf{HALO}$ which uses the Tunable Diode Laser Absorption Spectroscopy. To provide tropospheric and stratospheric measurements between $\textbf{2 ppmv}$ and $\textbf{10000 ppmv}$ two different lasers are implemented: One for high mixing ratios up to $\textbf{10000 ppmv}$ in the \textbf{1,4 \mu m} absorption band of the wate molecule and one for low mixingratios between $\textbf{2 ppmv}$ and $\textbf{400 ppmv}$ in the \textbf{2,6 \mum} ground vibrational band. For noncontact measurements of gas phase water an open path cell with two absorption paths has been developed. In contrast to the common Herriott setup of a cell with multiple absorption paths this cell has been designed as a White cell to include a direct fiber coupling. By using a computational based optimization for the optical absorption pths the disruptive interfering effects could be reduced below a level of $\textbf{266 ppmv}$ which is given by the used lasers. Due to the technical difficulties by [...

Satellitengestütze Schwerewellenmessungen in der Atmosphäre und Perspektiven einer zukünftigen ESA Mission (PREMIER)

Gravity waves play a key role in middle atmosphere dynamics. For an improved understanding of gravity waves and their interactions with the atmosphere, global modeling and measurements with high resolution are required. In this work we validate the gravity waves resolved in ECMWF ($\textbf{E}$uropean $\textbf{C}$entre for $\textbf{M}$edium-Range $\textbf{W}$eather $\textbf{F}$orecasts) model-data by comparison with gravity wave analysis of global satellite observations by SABER ($\textbf{S}$ounding of the $\textbf{A}$tmosphere using $\textbf{B}$roadband $\textbf{E}$mission $\textbf{R}$adiometry). The validation of the model-data shows that the modeled wave amplitudes are lowered by a factor of two in the troposphere and lower stratosphere. Above 50km altitude, the vertical resolution of ECMWF is reduced and accordingly the gravity waves are strongly damped. It is also shown that gravity waves with orographic sources are better represented in the model-data than convectively exited waves. Gravity waves with convective sources are suppressed by the resolution of the model and are only represented with small amplitudes. The validated ECMWF-data set can be used to simulate measurements of a future $\textbf{I}$nfrared $\textbf{L}$imb $\textbf{I}$mager (ILI). The investigation of the ILI-data shows that the measurement resolution is sufficient to calculate gravity wave momentum flux in both horizontal directions and that it will be possible to receive information about the propagation direction of the waves. The validated model-data are also used to improve the assumptions made by using temperature data to receive gravity wave momentum flux. The results of this study shows clearly the high potential of ILI-data for global measurements of gravity waves and the retrieval of gravity wave parameters. In particular momentum flux depending on the propagation direction of the waves will improve global circulation models

Plant Leaf Motion Estimation Using A 5D Affine Optical Flow Model

High accuracy motion analysis of plant leafs is of great interest for plant physiology, e.g., estimation of plant leaf orientation, or temporal and spatial growth maps, which are determined by divergence of 3D leaf motion. In this work a new method for plant leaf motion estimation is presented. The model is based on 5D affine optical flow, which allows simultaneous estimation of 3D structure, normals and 3D motion of objects using multi camera data. The method consists of several consecutive estimation procedures. In a first step the affine transformation in a 5D data set, i.e., 3D image sequences (x,y,t) of a 2D camera grid (sx,sy) is estimated within a differential framework. In this work the differential framework, based on an optical flow model, is extended by explicitly modeling of illumination changes. A second estimation process yields 3D structure and 3D motion parameters from the affine optical flow parameters. Modeling the 3D scene with local surface patches allows to derive a matrix defining the projection of 3D structure and 3D motion onto each camera sensor. The inverse projection matrix is used to estimate 3D structure (depth and surface normals) and 3D motion, including translation, rotation and acceleration from up to 24 affine optical flow parameters. In order to stabilize the estimation process optical flow parameters are estimated additionally separated for all cameras. A least squares estimator yields the solution minimizing the difference between optical flow parameters and the back projection of the 3D scene motion onto all cameras. Experiments on synthetic data demonstrate improved accuracy and improved robustness against illumination changes compared to methods proposed in recent literature. Moreover the new method allows estimation of additional parameters like surface normals, rotation and acceleration. Finally, plant data acquired under typical laboratory conditions is analyzed, showing the applicability of the method for plant physiology

Software tools zum interoperablen Austausch und zur visualisierung von Geodatensätzen über das Internet

Monitoring of the Earth and its atmosphere is essential for assessing the state of the environment and for measuring success of political measures to curb air pollution or mitigate climate change. The modern concept of monitoring the chemical composition of the atmosphere goes beyond the classical set-up of individual observational sites and involves a variety of measurement platforms (ground-based, ships, aircraft, satellites) and principles (chemical analysis, active and passive remote sensing, etc.). Numerical models play an increasingly important role for the interpretation of observations and their integration into a consistent global picture ..

Thermodynamische Eigenschaften gasförmiger und kondensierter Verbindungen für Hochtemperaturanwendungen

Panta rhei - everything flows – this famous quotation from the Greek philosopher Heraklit from around 500 BC which was gained in ancient times and still is valid recognises the observation that nothing is ever stable but is subjected to evolving processes. This first philosophical view can be readily transferred to materials sciences. Functional materials for high temperature applications show often severe changes in their properties during their operation. This is connected with the fact that the internal structure, their microstructure changes due to external influences. These are, for example, temperature changes, changes in pressure but also corrosive reactions with the surrounding atmosphere. To understand these processes knowledge of the constitution and properties of the thermo chemistry of these materials is important. In this study the scientific basis for the determination of thermodynamic parameters for materials research are presented. In addition to traditional experimental methods such as the Knudsen effusion mass spectrometry also novel approaches, as for example ab initio calculations are introduced. Examples are given concerning high temperature discharge lamps, intermetallic phases and chromium evaporation from SOFC interconnector steels demonstrate, how the combination of classical experimental methods with modern computer-based approaches leads to create extensive knowledge and consistent thermodynamic databases

Tomographic reconstruction of atmospheric volumes from infrared limb-imager measurements

State-of-the art nadir and limb-sounders, but also in situ measurements, do not offer the capability to highly resolve the atmosphere in all three dimensions. This leaves an observational gap with respect to small-scale structures that arise frequently in the atmosphere and that still lack a quantitative understanding. For instance, filaments and tropopause folds in the upper troposphere and lower stratosphere (UTLS) are crucial for its composition and variability. One way to achieve a highly resolved three-dimensional (3-D) picture of the atmosphere is the tomographic evaluation of limb-imager measurements. This thesis presents a methodology for the tomographic reconstruction of atmospheric constituents. To be able to deal with the large increase of observations and unknowns compared to conventional retrievals, great care is taken to reduce memory consumption and processing time. This method is used to evaluate the performance of two upcoming infrared limb-imager instruments and to prepare their missions...