Fluid venting and seepage at accretionary ridges: the Four Way Closure Ridge offshore SW Taiwan

Within the accretionary prism offshore SW Taiwan, widespread gas hydrate accumulations are postulated to occur based on the presence of a bottom simulating reflection. Methane seepage, however, is also widespread at accretionary ridges offshore SW Taiwan and may indicate a significant loss of methane bypassing the gas hydrate system. Four Way Closure Ridge, located in 1,500 m water depth, is an anticlinal ridge that would constitute an ideal trap for methane and consequently represents a site with good potential for gas hydrate accumulations. The analysis of high-resolution bathymetry, deep-towed sidescan sonar imagery, high-resolution seismic profiling and towed video observations of the seafloor shows that Four Way Closure Ridge is and has been a site of intensive methane seepage. Continuous seepage is mainly evidenced by large accumulations of authigenic carbonate precipitates, which appear to be controlled by the creation of fluid pathways through faulting. Consequently, Four Way Closure Ridge is not a closed system in terms of fluid migration and seepage. A conceptual model of the evolution of gas hydrates and seepage at accretionary ridges suggests that seepage is common and may be a standard feature during the geological development of ridges in accretionary prisms. The observation of seafloor seepage alone is therefore not a reliable indicator of exploitable gas hydrate accumulations at depth.     

What controls equatorial Atlantic winds in boreal spring?

The factors controlling equatorial Atlantic winds in boreal spring are examined using both observations and general circulation model (GCM) simulations from the coupled model intercomparison phase 5. The results show that the prevailing surface easterlies flow against the attendant pressure gradient and must therefore be maintained by other terms in the momentum budget. An important contribution comes from meridional advection of zonal momentum but the dominant contribution is the vertical transport of zonal momentum from the free troposphere to the surface. This implies that surface winds are strongly influenced by conditions in the free troposphere, chiefly pressure gradients and, to a lesser extent, meridional advection. Both factors are linked to the patterns of deep convection. Applying these findings to GCM errors indicates, that, consistent with the results of previous studies, the persistent westerly surface wind bias found in most GCMs is due mostly to precipitation errors, in particular excessive precipitation south of the equator over the ocean and deficient precipitation over equatorial South America. Free tropospheric influences also dominate the interannual variability of surface winds in boreal spring. GCM experiments with prescribed climatological sea-surface temperatures (SSTs) indicate that the free tropospheric influences are mostly associated with internal atmospheric variability. Since the surface wind anomalies in boreal spring are crucial to the development of warm SST events (Atlantic Niños), the results imply that interannual variability in the region may rely far less on coupled air–sea feedbacks than is the case in the tropical Pacific.     

State‐Led Innovation at the City Level: Policy Measures to Promote New Energy Vehicles in Shenzhen,China

Unlike many Western countries, the Chinese state has a much more active role in innovation that includes direct involvement with actors in innovation processes and the use of state capacity, money, and power to attain certain goals. With the rise of China, innovation processes that critically depend on state action, often labeled state‐led innovation, have thus received growing scholarly attention. However, only few contributions study the specific sector of new energy vehicles (NEV) and policy measures applied at the city level. This paper examines policy and planning tools used in Shenzhen, China, to assert innovation in the NEV industry, using an evaluation of documents and interviews. The paper finds that a city can play a decisive role in the implementation of innovation policy, and Chinese cities in particular make use of a broad set of innovation support measures ranging from binding quotas, public procurement, and incentives to bans and orders. The findings underline the importance of strong regulatory instruments that do not conform to the Western notion of market‐compliant policy, but nevertheless work effectively in the Chinese context. Moreover, the results highlight how successful policy support for innovation in the NEV can be implemented.     

Dust on the Outskirts of the Jovian System

The outer region of the jovian system between ∼50 and 300 jovian radii from the planet is found to be the host of a previously unknown dust population. We used the data from the dust detector aboard the Galileo spacecraft collected from December 1995 to April 2001 during Galileo's numerous traverses of the outer jovian system. Analyzing the ion amplitudes, calibrated masses and speeds of grains, and impact directions, we found about 100 individual events fully compatible with impacts of grains moving around Jupiter in bound orbits. These grains have moderate eccentricities and a wide range of inclinations—from prograde to retrograde ones. The radial number density profile of the micrometer-sized dust is nearly flat between about 50 and 300 jovian radii. The absolute number density level (∼10 km⁻³ with a factor of 2 or 3 uncertainty) surpasses by an order of magnitude that of the interplanetary background. We identify the sources of the bound grains with outer irregular satellites of Jupiter. Six outer tiny moons are orbiting the planet in prograde and fourteen in retrograde orbits. These moons are subject to continuous bombardment by interplanetary micrometeoroids. Hypervelocity impacts create ejecta, nearly all of which get injected into circumjovian space. Our analytic and numerical study of the ejecta dynamics shows that micrometer-sized particles from both satellite families, although strongly perturbed by solar tidal gravity and radiation pressure, would stay in bound orbits for hundreds of thousands of years as do a fraction of smaller grains, several tenths of a micrometer in radius, ejected from the prograde moons. Different-sized ejecta remain confined to spheroidal clouds embracing the orbits of the parent moons, with appreciable asymmetries created by the radiation pressure and solar gravity perturbations. Spatial location of the impacts, mass distribution, speeds, orbital inclinations, and number density of dust derived from the data are all consistent with the dynamical model.     

Cosmogenic neon in mineral separates from Kapoeta: No evidence for an irradiation of its parent body regolith by an early active Sun

Abstract— We present Ne data from plagioclase separates from the solar noble‐gas‐rich meteorite Kapoeta, obtained mainly by in vacuo etching. samples rich in solar gases contain an excess of cosmogenic ne compared to solar‐gas‐poor samples, testifying to an exposure to cosmic rays in the parent body regolith. The ²¹Ne/²²Ne ratio of the excess component is slightly lower than that of the Ne acquired during the meteoroid flight. Model calculations indicate that the observed isotopic composition of the excess Ne can be produced by galactic cosmic rays at a reasonable mean shielding of around a hundred to a few hundred grams per square centimeter. No substantial contribution from Ne produced by solar cosmic rays is needed to explain the data. We therefore conclude that they do not offer evidence for a substantially enhanced flux of solar energetic particles early in solar history, contrary to other claims. This conclusion is in agreement with solar flare track data.     

Data analysis pipeline for EChO end-to-end simulations

Atmospheric spectroscopy of extrasolar planets is an intricate business. Atmospheric signatures typically require a photometric precision of 1×10^?4 in flux over several hours. Such precision demands high instrument stability as well as an understanding of stellar variability and an optimal data reduction and removal of systematic noise. In the context of the EChO mission concept, we here discuss the data reduction and analysis pipeline developed for the EChO end-to-end simulator EChOSim. We present and discuss the step by step procedures required in order to obtain the final exoplanetary spectrum from the EChOSim ‘raw data’ using a simulated observation of the secondary eclipse of the hot-Neptune 55 Cnc e.     

Textural and compositional evidence for in situ crystallization of palisade bodies in coarse‐grained Ca‐Al‐rich inclusions

Palisade bodies, mineral assemblages with spinel shells, in coarse‐grained Ca‐, Al‐rich inclusions (CAIs) have been considered either as exotic “mini‐CAIs” captured by their host inclusions (Wark and Lovering 1982 ) or as in situ crystallization products of a bubble‐rich melt (Simon and Grossman 1997 ). In order to clarify their origins, we conducted a comprehensive study of palisade bodies in an Allende Type B CAI (BBA‐7), using electron backscatter diffraction (EBSD), micro‐computed tomography (Micro‐CT), electron probe microanalysis (EPMA), and secondary ion mass spectrometry (SIMS). New observations support the in situ crystallization mechanism: early/residual melt infiltrated into spinel‐shelled bubbles and crystallized inside. Evidence includes (1) continuous crystallography of anorthite from the interior of the palisade body to the surrounding host; (2) partial consolidation of two individual palisade bodies revealed by micro‐CT; (3) a palisade body was entirely enclosed in a large anorthite crystal, and the anorthite within the palisade body shows the same crystallographic orientation as the anorthite host; and (4) identical chemical and oxygen isotopic compositions of the constituent minerals between the palisade bodies and the surrounding host. Oxygen isotopic compositions of the major minerals in BBA‐7 are bimodal‐distributed. Spinel and fassaite are uniformly ¹⁶O‐rich with ?¹⁷O = ?23.3 ± 1.5‰ (2SD), and melilite and anorthite are homogeneously ¹⁶O‐poor with ?¹⁷O = ?3.2 ± 0.7‰ (2SD). The latter ?¹⁷O value overlaps with that of the Allende matrix (?¹⁷O ~ ?2.87‰) (Clayton and Mayeda 1999 ), which could be explained by secondary alteration with a ¹⁶O‐poor fluid in the parent body. The mobility of fluid could be facilitated by the high porosity (1.56–2.56 vol%) and connectivity (~0.17–0.55 vol%) of this inclusion.     

Silicon in iron meteorite metal

Abstract– We report Si concentrations in the metal phases of iron meteorites. Analyses were performed by secondary ion mass spectrometry using a CAMECA 1270 ion probe. The Si concentrations are low (0.09–0.46 μg g^?1), with no apparent difference in concentration between magmatic and nonmagmatic iron meteorites. Coexisting kamacite and Ni‐rich metal phases have similar Si contents. Thermodynamic calculations show that Fe,Ni‐metal in equilibrium with silicate melts at temperatures where metal crystallizes should contain approximately 100 times more Si than found in iron meteorites in this work. The missing Si may either occur as tiny silicate inclusions in metal or it may have diffused as Si‐metal into surrounding silicates at low temperatures. In both cases, extensive low‐temperature diffusion of Si in metal is required. It is therefore concluded that low Si in iron meteorites is a result of subsolidus reactions during slow cooling.     

Cross sections from 5 to 35 MeV for the reactions natMg(3He,x)26Al, 27Al(3He,x)26Al,natCa(3He,x)41Ca,and natCa(3He,x)36Cl: Implications for early irradiation in the solar system

Abstract– Cross sections were measured for the nuclear reactions ^natMg(³He,x)²⁶Al, ²⁷Al(³He,x)²⁶Al, ^natCa(³He,x)⁴¹Ca, and ^natCa(³He,x)³⁶Cl in the energy region from approximately 5–35 MeV. The rates of these reactions are important for studies of early solar system irradiation scenarios. The ²⁶Al, ³⁶Cl, and ⁴¹Ca were separated chemically, and the numbers of atoms produced in each reaction channel were measured using accelerator mass spectrometry (AMS). From these results, 26 cross sections were determined and compared with predictions of the TALYS code. Agreement is within 40% for most cross sections. Our measurements were used to model the production of ⁷Be, ¹⁰Be, ²⁶Al, and ⁴¹Ca in the early solar system. For projectiles ¹H, ³He, and ⁴He, we assumed energy spectra of the general form E^?α. For a wide range of parameterizations, the modeled ratios of ⁷Be/Be and ¹⁰Be/Be on the one hand and of ²⁶Al/²⁷Al and ⁴¹Ca/Ca on the other are coupled because the excitation functions for the relevant nuclear reactions have similar shapes. Modeling of a closed system with the constraint that ¹⁰Be/⁹Be = 0.001 fails to reproduce simultaneously the range of ⁷Be/⁹Be, ²⁶Al/²⁷Al, and ⁴¹Ca/Ca ratios inferred for the early solar system from studies of meteorites.     

On the influence of noise on measurements with three-dimensional hot-film or hot-wire probes

This paper describes the influence of noise on the u, v, and w wind components, which are measured by commonly used rectangular hot-film or hot-wire probes. It is shown that the distortion of the u, v, and w turbulence spectra may be entirely different, even if all three measured cooling velocities are equally disturbed by the same noise signal. A practical formalism is given for estimating the influence of any cooling velocity noise on the spectra and cospectra of u, v, and w. With inverted matrices, the original spectrum of a noise signal in the cooling velocities can be calculated from the observed u, v, and w spectra, assuming that the undisturbed shape of them is known.This work was supported by the Sonderforschungsbereich Meeresforschung of the Deutsche Forschungsgemeinschaft.