Organic sedimentary deposits in Titan’s dry lakebeds: Probable evaporite

We report the discovery of organic sedimentary deposits at the bottom of dry lakebeds near Titan’s north pole in observations from the Cassini Visual and Infrared Mapping Spectrometer (VIMS). We show evidence that the deposits are evaporitic, making Titan just the third known planetary body with evaporitic processes after Earth and Mars, and is the first that uses a solvent other than water.     

Geology of the Selk crater region on Titan from Cassini VIMS observations

Observations of Titan obtained by the Cassini Visual and Infrared Mapping Spectrometer (VIMS) have revealed Selk crater, a geologically young, bright-rimmed, impact crater located ∼800 km north-northwest of the Huygens landing site. The crater rim-crest diameter is ∼90 km; its floor diameter is ∼60 km. A central pit/peak, 20-30 km in diameter, is seen; the ratio of the size of this feature to the crater diameter is consistent with similarly sized craters on Ganymede and Callisto, all of which are dome craters. The VIMS data, unfortunately, are not of sufficient resolution to detect such a dome. The inner rim of Selk crater is fluted, probably by eolian erosion, while the outer flank and presumed ejecta blanket appear dissected by drainages (particularly to the east), likely the result of fluvial erosion. Terracing is observed on the northern and western walls of Selk crater within a 10-15 km wide terrace zone identified in VIMS data; the terrace zone is bright in SAR data, consistent with it being a rough surface. The terrace zone is slightly wider than those observed on Ganymede and Callisto and may reflect differences in thermal structure and/or composition of the lithosphere. The polygonal appearance of the crater likely results from two preexisting planes of weakness (oriented at azimuths of 21° and 122° east of north). A unit of generally bright terrain that exhibits similar infrared-color variation and contrast to Selk crater extends east-southeast from the crater several hundred kilometers. We informally refer to this terrain as the Selk “bench.” Both Selk and the bench are surrounded by the infrared-dark Belet dune field. Hypotheses for the genesis of the optically bright terrain of the bench include: wind shadowing in the lee of Selk crater preventing the encroachment of dunes, impact-induced cryovolcanism, flow of a fluidized-ejecta blanket (similar to the bright crater outflows observed on Venus), and erosion of a streamlined upland formed in the lee of Selk crater by fluid flow. Vestigial circular outlines in this feature just east of Selk’s ejecta blanket suggest that this might be a remnant of an ancient, cratered crust. Evidently the southern margin of the feature has sufficient relief to prevent the encroachment of dunes from the Belet dune field. We conclude that this feature either represents a relatively high-viscosity, fluidized-ejecta flow (a class intermediate to ejecta blankets and long venusian-style ejecta flows) or a streamlined upland remnant that formed downstream from the crater by erosive fluid flow from the west-northwest.     

Governance arrangements targeting diversity in Europe: how New Public Management impacts working with social cohesion

This article analyses how policies to foster social cohesion within diverse and unequal urban contexts are affected by New Public Management and austerity policies. Based on the analysis of a handful of governance arrangements in three cities that differ in their institutional structure and diversity policy approaches (Copenhagen, Leipzig and Milan), it is shown that negative effects are quite widespread yet cushioned by a strong welfare state structure, solid local government and high priority given to the recognition of diversity. Nevertheless, the shift towards the application of market logic to social work reduces innovative potential, increases efforts spent on procedures and weakens public coordination.     

Ceres’ spectral link to carbonaceous chondrites—Analysis of the dark background materials

Ceres’ surface has commonly been linked with carbonaceous chondrites (CCs) by ground‐based telescopic observations, because of its low albedo, flat to red‐sloped spectra in the visible and near‐infrared (VIS/NIR) wavelength region, and the absence of distinct absorption bands, though no currently known meteorites provide complete spectral matches to Ceres. Spatially resolved data of the Dawn Framing Camera (FC) reveal a generally dark surface covered with bright spots exhibiting reflectance values several times higher than Ceres’ background. In this work, we investigated FC data from High Altitude Mapping Orbit (HAMO) and Ceres eXtended Juling (CXJ) orbit (~140 m/pixel) for global spectral variations. We found that the cerean surface mainly differs by spectral slope over the whole FC wavelength region (0.4–1.0 μm). Areas exhibiting slopes ?1 constitute only ~3% of the cerean surface and mainly occur in the bright material in and around young craters, whereas slopes ≥?10% μm^?1 occur on more than 90% of the cerean surface; the latter being denoted as Ceres’ background material in this work. FC and Visible and Infrared Spectrometer (VIR) spectra of this background material were compared to the suite of CCs spectrally investigated so far regarding their VIS/NIR region and 2.7 μm absorption, as well as their reflectance at 0.653 μm. This resulted in a good match to heated CI Ivuna (heated to 200–300 °C) and a better match for CM1 meteorites, especially Moapa Valley. This possibly indicates that the alteration of CM2 to CM1 took place on Ceres.     

The Solar Oscillations Investigation - Michelson Doppler Imager

The Solar Oscillations Investigation (SOI) uses the Michelson Doppler Imager (MDI) instrument to probe the interior of the Sun by measuring the photospheric manifestations of solar oscillations. Characteristics of the modes reveal the static and dynamic properties of the convection zone and core. Knowledge of these properties will improve our understanding of the solar cycle and of stellar evolution. Other photospheric observations will contribute to our knowledge of the solar magnetic field and surface motions. The investigation consists of coordinated efforts by several teams pursuing specific scientific objectives.The instrument images the Sun on a 1024² CCD camera through a series of increasingly narrow spectral filters. The final elements, a pair of tunable Michelson interferometers, enable MDI to record filtergrams with a FWHM bandwidth of 94 m. Normally 20 images centered at 5 wavelengths near the Ni I 6768 spectral line are recorded each minute. MDI calculates velocity and continuum intensity from the filtergrams with a resolution of 4 over the whole disk. An extensive calibration program has verified the end-to-end performance of the instrument.To provide continuous observations of the longest-lived modes that reveal the internal structure of the Sun, a carefully-selected set of spatial averages are computed and downlinked at all times. About half the time MDI will also be able to downlink complete velocity and intensity images each minute. This high rate telemetry (HRT) coverage is available for at least a continuous 60-day interval each year and for 8 hours each day during the rest of the year. During the 8-hour HRT intervals, 10 of the exposures each minute can be programmed for other observations, such as measurements in MDI's higher resolution (1.25) field centered about 160 north of the equator; meanwhile, the continuous structure program proceeds during the other half minute. Several times each day, polarizers will be inserted to measure the line-of-sight magnetic field.MDI operations will be scheduled well in advance and will vary only during the daily 8-hour campaigns. Quick-look and summary data, including magnetograms, will be processed immediately. Most high-rate data will be delivered only by mail to the SOI Science Support Center (SSSC) at Stanford, where a processing pipeline will produce 3 Terabytes of calibrated data products each year. These data products will be analyzed using the SSSC and the distributed resources of the co-investigators. The data will be available for collaborative investigations.The MDI Engineering Team leaders include: D. Akin, B. Carvalho, R. Chevalier, D. Duncan, C. Edwards, N. Katz, M. Levay, R. Lindgren, D. Mathur, S. Morrison, T. Pope, R. Rehse, and D. Torgerson.     

Hazard assessment at San Martín volcano based on geological record, numerical modeling, and spatial analysis

The San Martín shield volcano, located in the Los Tuxtlas Volcanic Field, has experienced effusive shield-building activity, as well as explosive eruptions, as evidenced by direct observations during the last eruption in 1793. The threat to the surrounding villages consists principally of lahars, especially because of the tropical climate in the region. Ash fallout and lava flows represent additional hazards. In addition, the surrounding Quaternary monogenetic field includes more than 300 scoria cones and about 40 explosion craters (mainly maars) that also represent a hazard source. In the present study we constructed hazard maps using field data, orthophotos, spatial analysis, and specialized software (LAHARZ and HAZMAP) to deliminate lahar inundation zones, areas that could potentially be affected by ash fallout (including the evaluation of houses prone to roof collapse due to ash load), and the most susceptible areas for hosting future monogenetic vent formation.     

The record of historic earthquakes in lake sediments of Central Switzerland

Deformation structures in lake sediments in Central Switzerland can be attributed to strong historic earthquakes. The type and spatial distribution of the deformation structures reflect the historically documented macroseismic intensities thus providing a useful calibration tool for paleoseismic investigations in prehistoric lake sediments.The Swiss historical earthquake catalogue shows four moderate to strong earthquakes with moment magnitudes of M_w=5.7 to M_w=6.9 and epicentral intensities of I₀=VII to I₀=IX that affected the area of Central Switzerland during the last 1000 years. These are the 1964 Alpnach, 1774 Altdorf, 1601 Unterwalden, and 1356 Basel earthquakes. In order to understand the effect of these earthquakes on lacustrine sediments, four lakes in Central Switzerland (Sarner See, Lungerer See, Baldegger See, and Seelisberg Seeli) were investigated using high-resolution seismic data and sediment cores. The sediments consist of organic- and carbonate-rich clayey to sandy silts that display fine bedding on the centimeter to millimeter scale. The sediments are dated by historic climate and environmental records, ¹³⁷Cs activity, and radiocarbon ages. Deformation structures occur within distinct zones and include large-scale slumps and rockfalls, as well as small-scale features like disturbed and contorted lamination and liquefaction structures. These deformations are attributed to three of the abovementioned earthquakes. The spatial distribution of deformation structures in the different lakes clearly reflects the historical macroseismic dataset: Lake sediments are only affected if they are situated within an area that underwent groundshaking not smaller than intensity VI to VII. We estimate earthquake size by relating the epicentral distance of the farthest liquefaction structure to earthquake magnitude. This relationship is in agreement with earthquake size estimations based on the historical dataset.     

Climate change impacts on global agriculture

Based on predicted changes in the magnitude and distribution of global precipitation, temperature and river flow under the IPCC SRES A1B and A2 scenarios, this study assesses the potential impacts of climate change and CO₂ fertilization on global agriculture. The analysis uses the new version of the GTAP-W model, which distinguishes between rainfed and irrigated agriculture and implements water as an explicit factor of production for irrigated agriculture. Future climate change is likely to modify regional water endowments and soil moisture. As a consequence, the distribution of harvested land will change, modifying production and international trade patterns. The results suggest that a partial analysis of the main factors through which climate change will affect agricultural productivity provide a false appreciation of the nature of changes likely to occur. Our results show that global food production, welfare and GDP fall in the two time periods and SRES scenarios. Higher food prices are expected. No matter which SRES scenario is preferred, we find that the expected losses in welfare are significant. These losses are slightly larger under the SRES A2 scenario for the 2020s and under the SRES A1B scenario for the 2050s. The results show that national welfare is influenced both by regional climate change and climate-induced changes in competitiveness.     

Growing Operational Use of FY-3 Data in the ECMWF System

This paper reviews the data quality and impact of observations from the FY-3 satellite series used operationally in the ECMWF system. This includes data from the passive microwave radiometers MWHS-1, MWHS-2 and MWRI, as well as observations from the radio occultation receiver GNOS. Evaluations against background equivalents show that the quality of the observations is broadly comparable to that of similar instruments on other polar-orbiting satellites, even though biases for the passive microwave observations can be somewhat larger and more complex for some channels. An observing system experiment shows that the FY-3 instruments jointly contribute significantly to the forecast skill in the ECMWF system. Positive impact of up to 2% is seen for most variables out to the day-2 forecasts over hemispheric scales, with significant benefits for total column water vapor or for temperature and wind in the stratosphere out to day 4.     

1D joint multi‐offset inversion of time‐domain marine controlled source electromagnetic data

The accurate estimation of sub‐seafloor resistivity features from marine controlled source electromagnetic data using inverse modelling is hindered due to the limitations of the inversion routines. The most commonly used one‐dimensional inversion techniques for resolving subsurface resistivity structures are gradient‐based methods, namely Occam and Marquardt. The first approach relies on the smoothness of the model and is recommended when there are no sharp resistivity boundaries. The Marquardt routine is relevant for many electromagnetic applications with sharp resistivity contrasts but subject to the appropriate choice of a starting model. In this paper, we explore the ability of different 1D inversion schemes to derive sub‐seafloor resistivity structures from time domain marine controlled source electromagnetic data measured along an 8‐km‐long profile in the German North Sea. Seismic reflection data reveal a dipping shallow amplitude anomaly that was the target of the controleld source electromagnetic survey. We tested four inversion schemes to find suitable starting models for the final Marquardt inversion. In this respect, as a first scenario, Occam inversion results are considered a starting model for the subsequent Marquardt inversion (Occam–Marquardt). As a second scenario, we employ a global method called Differential Evolution Adaptive Metropolis and sequentially incorporate it with Marquardt inversion. The third approach corresponds to Marquardt inversion introducing lateral constraints. Finally, we include the lateral constraints in Differential Evolution Adaptive Metropolis optimization, and the results are sequentially utilized by Marquardt inversion. Occam–Marquardt may provide accurate estimation of the subsurface features, but it is dependent on the appropriate conversion of different multi‐layered Occam model to an acceptable starting model for Marquardt inversion, which is not straightforward. Employing parameter spaces, the Differential Evolution Adaptive Metropolis approach can be pertinent to determine Marquardt a priori information; nevertheless, the uncertainties in Differential Evolution Adaptive Metropolis optimization will introduce some inaccuracies in Marquardt inversion results. Laterally constrained Marquardt may be promising to resolve sub‐seafloor features, but it is not stable if there are significant lateral changes of the sub‐seafloor structure due to the dependence of the method to the starting model. Including the lateral constraints in Differential Evolution Adaptive Metropolis approach allows for faster convergence of the routine with consistent results, furnishing more accurate estimation of a priori models for the subsequent Marquardt inversion.