Stratigraphic and geotechnical characterization of regionally extensive and highly competent shallow sand units in the southern North Sea

A detailed stratigraphic and geotechnical investigation of the uppermost 50 m below the sea floor was carried out for parts of the German North Sea sector using combined information from shallow seismic reflection surveys, 50-m-long sediment cores and cone penetration tests covering an area of ~150 km². While most recent studies concentrate on unusual features such as buried tunnel- or river-valleys, this study focused on the less well understood, regionally dominant sand units deposited after the retreat of the last glaciers in this region. We identified two sandy units which dominate the late- to post-Saalian geology: (i) the Upper Fluvial Member, believed to be derived from deposition of the Weser, Ems and Elbe palaeorivers as well as other tributaries of the Elbe Palaeovalley in the NE during the Saalian; and (ii) the Aeolian Member, which correlates with periglacial deposits of Weichselian age. Additionally, a Saalian Buried Valley Member believed to comprise fluvial deposit was also identified. Key stratigraphic units within the uppermost 50 m below the sea floor were also identified and mapped. Detailed geotechnical properties were obtained for each of the individual stratigraphic units. The regional extent of the Aeolian and Upper Fluvial Members was documented in the region west of the Elbe Palaeovalley and south of the Dogger Bank, where their geotechnical properties are important for foundation design. In conclusion, the study complements the established regional geotechno-stratigraphy and offers new and detailed publically accessible information beneficial for offshore wind farm development within the region.     

Towards a framework for geospatial tangible user interfaces in collaborative urban planning

The increasing complexity of urban planning projects today requires new approaches to better integrate stakeholders with different professional backgrounds throughout a city. Traditional tools used in urban planning are designed for experts and offer little opportunity for participation and collaborative design. This paper introduces the concept of geospatial tangible user interfaces (GTUI) and reports on the design and implementation as well as the usability of such a GTUI to support stakeholder participation in collaborative urban planning. The proposed system uses physical objects to interact with large digital maps and geospatial data projected onto a tabletop. It is implemented using a PostGIS database, a web map server providing OGC web services, the computer vision framework reacTIVision, a Java-based TUIO client, and GeoTools. We describe how a GTUI has be instantiated and evaluated within the scope of two case studies related to real world collaborative urban planning scenarios. Our results confirm the feasibility of our proposed GTUI solutions to (a) instantiate different urban planning scenarios, (b) support collaboration, and (c) ensure an acceptable usability.     

On the long-term stability of terrestrial reference frame solutions based on Kalman filtering

The Global Geodetic Observing System requirement for the long-term stability of the International Terrestrial Reference Frame is 0.1 mm/year, motivated by rigorous sea level studies. Furthermore, high-quality station velocities are of great importance for the prediction of future station coordinates, which are fundamental for several geodetic applications. In this study, we investigate the performance of predictions from very long baseline interferometry (VLBI) terrestrial reference frames (TRFs) based on Kalman filtering. The predictions are computed by extrapolating the deterministic part of the coordinate model. As observational data, we used over 4000 VLBI sessions between 1980 and the middle of 2016. In order to study the predictions, we computed VLBI TRF solutions only from the data until the end of 2013. The period of 2014 until 2016.5 was used to validate the predictions of the TRF solutions against the measured VLBI station coordinates. To assess the quality, we computed average WRMS values from the coordinate differences as well as from estimated Helmert transformation parameters, in particular, the scale. We found that the results significantly depend on the level of process noise used in the filter. While larger values of process noise allow the TRF station coordinates to more closely follow the input data (decrease in WRMS of about 45%), the TRF predictions exhibit larger deviations from the VLBI station coordinates after 2014 (WRMS increase of about 15%). On the other hand, lower levels of process noise improve the predictions, making them more similar to those of solutions without process noise. Furthermore, our investigations show that additionally estimating annual signals in the coordinates does not significantly impact the results. Finally, we computed TRF solutions mimicking a potential real-time TRF and found significant improvements over the other investigated solutions, all of which rely on extrapolating the coordinate model for their predictions, with WRMS reductions of almost 50%.     

Geochemical and mineralogical composition of black weathering crusts on limestones from seven different European countries

Twenty-seven samples of black weathering crust and host carbonates were studied from seven European countries (Germany, Hungary, Belgium, Czech Republic, France, Italy and Poland) representing 11 different sites. The samples were collected for sites for which long-term air pollution records are available. The mineralogical analyses (XRD, polarizing microscopy, SEM) have shown that despite decreasing SO₂ emissions crust samples are still very rich in gypsum. Further, in all host rock samples gypsum was also detected. Good correlations (R² > 0.9) were also found between water-soluble calcium and gypsum content and between sulphate and gypsum content both for black crusts and host rocks. The black gypsum crusts are four or five times richer in sulphate than the host rock. The conductivity of dissolved crust and host rock samples also shows a positive correlation with gypsum content of the samples. LA-ICP-MS analyses allowed the detection of high Pb-levels in black crusts and a negative shift in lead concentration at the crust/host rock transition. The lead content of the host rock is 2–5 mg/kg, while that of the crust is 3–25 mg/kg in the sample collected from Germany, while in the Belgian sample these values are 2–14 mg/kg and 80–870 mg/kg for the host rock and crust, respectively. The GC–MS technique allowed to detect the PAH content of black crusts and host rocks. The former one contains 0.6–15.6 (102.5) mg/kg, while in the host rock values between 0.2 and 2.4 mg/kg were found. The present study suggests that still large amounts of air pollution-related minerals and organic pollutants are found in the black weathering crusts of European carbonate buildings despite decreasing trends in air pollution.     

The survival and disruption of cold dark matter microhaloes: implications for direct and indirect detection experiments

If the dark matter particle is a neutralino, then the first structures to form are cuspy cold dark matter (CDM) haloes collapsing after redshifts   z ≈ 100  in the mass range  10⁻⁶–10⁻³ M_⊙  . We carry out a detailed study of the survival of these microhaloes in the Galaxy as they experience tidal encounters with stars, molecular clouds, and other dark matter substructures. We test the validity of analytic impulsive heating calculations using high-resolution N -body simulations. A major limitation of analytic estimates is that mean energy inputs are compared to mean binding energies, instead of the actual mass lost from the system. This energy criterion leads to an overestimate of the stripped mass and an underestimate of the disruption time-scale, since CDM haloes are strongly bound in their inner parts. We show that a significant fraction of material from CDM microhaloes can be unbound by encounters with Galactic substructure and stars; however, the cuspy central regions remain relatively intact. Furthermore, the microhaloes near the solar radius are those which collapse significantly earlier than average and will suffer very little mass-loss. Thus, we expect a fraction of surviving bound microhaloes, a smooth component with narrow features in phase space, which may be uncovered by direct detection experiments, as well as numerous surviving cuspy cores with proper motions of arcminutes per year, which can be detected indirectly via their annihilation into gamma-rays.     

The Jovian stratosphere in the ultraviolet

The center-of-disk reflectivity of Jupiter in the wavelength range from 1450 to 3150A?has been computed from 30 low-dispersion IUE spectra taken during solar maximum in 1978–1980. A vertically inhomogeneous radiative transfer program is used to compute model reflectivities of various stratospheric compositions for comparison. Ammonia and acetylene are well determined because they show narrow absorption bands in the ultraviolet. Above 1800A?, these two gases provide a good fit to the data, but not below. At shorter wavelengths the fit would be much improved by a small amount (5–15 ppb) of propadiene/allene (C₃H₄). Voyager IRIS spectra show that the IR bands of allene are not strong enough to be detected in such a small amount. Additional absorption around 1600A?can be reproduced best with the presence of cyclopropane (C₃H₆, <15ppb), although other absorbers (e.g., hydrocarbon molecules with more than three carbon atoms, oxygen- or nitrogen-containing molecules, or a high-attitude haze) could also explain the spectrum in this region. The data are too noisy to detect possible CO Cameron band absorption near 2000A?.     

Rapid mapping in support of emergency response after earthquake events

Earthquakes and other sudden onset natural disasters require quick and efficient emergency response. Earth observation (EO) data can make a valuable contribution to emergency response efforts if provided within hours and at the most days after the event. Mechanisms like the International Charter Space and Major Disasters and the European GMES Emergency Response Service provide the necessary basis for an efficient and rapid provision of EO data and damage mapping. This paper provides an overview of earthquake damage assessment methodologies, their potential and their limitations in a rapid mapping context and outlines a methodology for casualty estimation. Two case studies—the 2010 Haiti earthquake and the 2011 Van (Turkey) earthquake—are presented, where DLR’s Center for satellite-based crisis information (ZKI) provided rapid damage maps using a team-based visual interpretation approach. Additionally, the application of a casualty estimation method in the immediate aftermath of an earthquake is outlined.