ALBERT

Description: The deconvolution of the deformation history of rocks is one of the main goals of texture analysis in geology. The frequent observation that the macroscopic structures are obliquely oriented with respect to the margins of the deformation zone gave rise to the hypotheses that the deformation path might be complex, and that the lattice preferred orientation of the rock-forming minerals should reflect such complicated deformation conditions as well. Hence, texture determinations of polyphase rock samples were carried out and the relationship of the mineral textures to the commonly used sample reference frame foliationlineation, which is assumed to represent the principal axes of the bulk finite strain tensor, was investigated. It was confirmed that particular mineral textures are typical for different stages of the deformation path. Especially the quartz textures exhibit an uncommon but consistent deviation from the sample reference frame, which is consistent with respect to the geographical coordinates, too. Such a characteristic may be used to evaluate the direction of a large-scale horizontal shear component, which is known as the transpressive shear vector in the geological literature.

Description: The microstructural and quantitative texture analyses of a naturally deformed calcite mylonite, a dolomite mylonite and a dolomitic calcite mylonite reveal different texture asymmetries for comparable deformation conditions. Calcite shows a c-axis maximum rotated against the shear sense with regard to the main shear plane. In contrast, the dolomite shows a c-axis maximum rotated with the shear sense. In accordance with the experimental and simulated textures from the literature, this difference proves e-twinning and r-slip for calcite and f-twinning and c-slip for dolomite as the main deformation mechanisms. The dolomitic calcite mylonite shows for both the calcite and the dolomite a c-axis maximum rotated against the shear sense. On account of the microstructure of this sample, the dolomite texture has been passively overtaken from the deformation texture of calcite during a late-deformative dolomitization. The results significantly contribute to the interpretation that the sampled shear zone is a transpressive strikeslip fault.

Description: Urban air quality and human health are among the key aspects of future urban planning. In order to address pollutants such as ozone and particulate matter, efforts need to be made to quantify and reduce their concentrations. One important aspect in understanding urban air quality is the influence of urban vegetation which may act as both emitter and sink for trace gases and aerosol particles. In this context, the "Berlin Air quality and Ecosystem Research: Local and long-range Impact of anthropogenic and Natural hydrocarbons 2014" (BAERLIN2014) campaign was conducted between 2 June and 29 August in the metropolitan area of Berlin and Brandenburg, Germany. The predominant goals of the campaign were (1) the characterization of urban gaseous and particulate pollution and its attribution to anthropogenic and natural sources in the region of interest, especially considering the connection between biogenic volatile organic compounds and particulates and ozone; (2) the quantification of the impact of urban vegetation on organic trace gas levels and the presence of oxidants such as ozone; and (3) to explain the local heterogeneity of pollutants by defining the distribution of sources and sinks relevant for the interpretation of model simulations. In order to do so, the campaign included stationary measurements at urban background station and mobile observations carried out from bicycle, van and airborne platforms. This paper provides an overview of the mobile measurements (Mobile BAERLIN2014) and general conclusions drawn from the analysis. Bicycle measurements showed micro-scale variations of temperature and particulate matter, displaying a substantial reduction of mean temperatures and particulate levels in the proximity of vegetated areas compared to typical urban residential area (background) measurements. Van measurements extended the area covered by bicycle observations and included continuous measurements of O3, NOx, CO, CO2 and point-wise measurement of volatile organic compounds (VOCs) at representative sites for traffic- and vegetation-affected sites. The quantification displayed notable horizontal heterogeneity of the short-lived gases and particle number concentrations. For example, baseline concentrations of the traffic-related chemical species CO and NO varied on average by up to ±22.2 and ±63.5 %, respectively, on the scale of 100 m around any measurement location. Airborne observations revealed the dominant source of elevated urban particulate number and mass concentrations being local, i.e., not being caused by long-range transport. Surface-based observations related these two parameters predominantly to traffic sources. Vegetated areas lowered the pollutant concentrations substantially with ozone being reduced most by coniferous forests, which is most likely caused by their reactive biogenic VOC emissions. With respect to the overall potential to reduce air pollutant levels, forests were found to result in the largest decrease, followed by parks and facilities for sports and leisure. Surface temperature was generally 0.6–2.1 °C lower in vegetated regions, which in turn will have an impact on tropospheric chemical processes. Based on our findings, effective future mitigation activities to provide a more sustainable and healthier urban environment should focus predominantly on reducing fossil-fuel emissions from traffic as well as on increasing vegetated areas.

Description: GRACE Follow-On, the successor of the GRACE mission, continues the legacy of Earth gravity field recovery missions. This experiment’s data is an essential contribution to observing and understanding Earths changing climate conditions by, e.g., observing changes in groundwater levels and the mass of ice shields. Activities on successor missions to guarantee an uninterrupted observation of the gravity field are ongoing.The primary instrument in these missions will be a heterodyne laser interferometer based on the success of the GRACE-FO mission and its superior noise performance compared to the previous microwave ranging. In this talk, we discuss the effect of distorted optical wavefronts on the length readout. We are developing tools to measure the wavefront on ground and extrapolate it over the long distance to the remote spacecraft. We also investigate the potential influence of such distortions together with pointing jitter of the spacecraft.