Structure and ageing of oceanic crust at 14°S on the East Pacific Rise     

Ingo Grevemeyer  Wilfried Weigel  & Claudia Jennrich† 《Geophysical Journal International》1998,135(2):573-584

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Sunglitter radiance modulation by internal waves     

Dr. Ingo Hennings  Margitta Metzner 《Ocean Dynamics》1996,48(2):121-132

Summary Quantitative sunglitter radiance modulations at the ocean surface due to internal waves were calculated applying a simple first order theory. The results have been compared with the image data of internal wave signatures northeast of Nantucket Shoals off the coast of Massachusetts, U.S.A., taken by the Earth Terrain Camera (ETC) during the Skylab mission. The maximum magnitudes of sunglitter radiance modulations predicted by the theory are comparable to the satellite image data. The extreme values of calculated modulations depend only weakly on the wavelength of the internal wave signature. This is consistent with the analysed ETC data. On the other hand, the shapes of simulated and measured image intensity transects across an internal wave packet are different. This may possibly be explained by the assumed idealized sinusoidal type of thermocline used in the calculations. The theory predicts that sunglint signatures of internal waves are advected relative to positions of extreme slope regions of the thermocline due to currents.

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Strahldichtemodulation des Sonnenglitzerns durch interne Wellen

Zusammenfassung Quantitative Strahldichtemodulationen des Sonnenglitzerns an der Meeresoberfl?che durch interne Wellen werden unter Verwendung einer einfachen ersten Ordnungstheorie berechnet. Die Ergebnisse werden mit Bilddaten von internen Wellensignaturen nord?stlich von Nantucket Shoals vor der Küste von Massachusetts, U.S.A., verglichen, die w?hrend der Skylab-Mission von der Erdbeobachtungskamera (ETC) aufgenommen wurden. Die Werte der maximalen Strahldichtemodulation des Sonnenglitzerns, die von der Theorie vorhergesagt werden, sind mit den Satellitenbilddaten vergleichbar. Die Extremwerte der berechneten Modulationen h?ngen nur schwach von der Wellenl?nge der internen Wellensignaturen ab. Dieses stimmt mit den analysierten ETC Daten überein. Auf der anderen Seite sind die Kurvenverl?ufe zwischen den simulierten und gemessenen Bildintensit?tsprofilen entlang eines internen Wellenpaketes unterschiedlich. Dieses kann m?glicherweise durch den angenommenen idealisierten sinusf?rmigen Typ der Thermokline erkl?rt werden, der für die Berechnungen verwendet wurde. Die Theorie macht die Vorhersage, da? Signaturen des Sonnenglitzerns von internen Wellen durch Str?mungen advektiert werden relativ zu den Positionen der extremen Neigungsregionen der Thermokline.

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Comparative aeronomy in the solar system     

Ingo Mueller-Wodarg  Emma Bunce 《Astronomy& Geophysics》2003,44(2):2.33-2.33

The coupled upper atmospheres, ionospheres and magnetospheres of the planets were the subject of a joint RAS–G/MIST discussion meeting hosted by the RAS on 10 January 2003, organized by Ingo Mueller-Wodarg and Emma Bunce . The scientific programme consisted of 10 presentations by speakers from the UK, France, USA and Australia.  相似文献   

The influence of cosmic-ray production on extinct nuclide systems   总被引：1，自引：0，他引：1  

Ingo Leya  Rainer Wieler 《Geochimica et cosmochimica acta》2003,67(3):529-541

Variations in the atomic abundances of ⁵³Cr, ⁹²Zr, ⁹⁸Ru, ⁹⁹Ru, and ¹⁸²W in meteorites and lunar samples relative to terrestrial values may imply the early decay of radioactive ⁵³Mn, ⁹²Nb, ⁹⁸Tc, ⁹⁹Tc and ¹⁸²Hf, respectively. From this one can deduce nucleosynthetic sites and early solar system timescales. Because these effects are very small, production and consumption of the respective isotopes by cosmic-ray interactions is a concern. It has recently been demonstrated that ¹⁸²W production by neutron capture reactions on ¹⁸¹Ta is crucial for most lunar samples (Leya et al., 2000a). In this study the neutron fluence of each sample was estimated from its nominal cosmic-ray exposure age as deduced from noble gas data. This approach overestimates the true cosmogenic isotopic shift for samples that might have been irradiated very close to the regolith surface. Here we therefore combine our model calculations with the neutron dose proxies ¹⁵⁷Gd/¹⁵⁸Gd and ¹⁴⁹Sm/¹⁵⁰Sm. This allows us to accurately correct the measured W isotopic data for cosmic-ray induced shifts without the explicit knowledge of the exposure age or the shielding depth of the sample simply by measuring ¹⁵⁷Gd/¹⁵⁸Gd and/or ¹⁴⁹Sm/¹⁵⁰Sm in an aliquot. In addition we present new model results for the GCR-induced effects on ⁵³Mn-⁵³Cr, ⁹²Nb-⁹²Zr and ⁹⁸Tc-⁹⁹Tc-⁹⁸Ru-⁹⁹Ru. For each of these systems, except Tc-Ru, a proper cosmic-ray dose proxy is given, permitting the accurate correction of measured isotopic ratios for cosmogenic contributions.  相似文献   

Synthesis, properties and stability of end member boromuscovite, KAl2[BSi3O10](OH)2     

Ingo Jung  Werner Schreyer 《Contributions to Mineralogy and Petrology》2002,143(6):684-693

End member boromuscovite, with nearly the ideal composition, was synthesized as a single phase from mixtures of its own composition, or with excess boron and water, at high pressures of between 15 and 30 kbar at 700 °C. The mica synthesized consists of a mixture of 2M₁ and 1M polytypes with the cell dimensions of 2M₁: a=5.071(4), b=8.786(4), c=19.830(89) Å, #=95.84(12)°, V=878.5(1.4) ų; and 1M: a=5.059(5), b=8.819(6), c=10.025(17) Å, #=101.39(57)°, V=438.4(1.3) Å. The IR spectrum shows characteristic differences relative to that of muscovite. DTA registers an endothermic peak due to dehydration breakdown above 680 °C. Seeded experiments indicate that boromuscovite is a high-pressure phase requiring minimum pressures of 3 to 10 kbar at temperatures that concomitantly increase from 300 to 750 °C. At lower pressures, the anhydrous solid assemblage K-feldspar + Al-borate (probably Al₄B₂O₉) coexists with a vapor rich in boric acid. The conversion of this assemblage to boromuscovite is connected with increases in the coordination number of B from [3] to [4], and of Al from [4] to [6]. Above 10 kbar, the boromuscovite stability field is limited along its high-temperature side by congruent (or incongruent?) melting of the mica, starting near 750 °C and 10 kbar and increasing to about 900 °C at 50 kbar, although, at such very high pressures a supercritical fluid may be present. Because, even in the presence of excess-boron fluid, the synthetic mica shows invariable X-ray properties, it is concluded that one B atom per formula unit represents the maximum, and - contrary to olenitic tourmalines - no further substitution of Si by B linked with addition of hydrogen takes place. In contrast to muscovite, KAl₂[AlSi₃O₁₀](OH)₂, end member boromuscovite is not stable under normal P-T conditions of the Continental Crust along a 30 °C/km geotherm, and especially not during the intrusion of acidic igneous rocks including their pegmatites, which may explain its scarcity in nature. However, it may form in the waning hydrothermal stages of deep-seated (>10.5 km) pegmatites and - providing sufficient boron is available - in HP/LT subduction zone environments, where it may carry boron to considerable depths.  相似文献   

Phytoplankton und Primärproduktion einiger ostschweizerischer Seen und des Bodensees     

Ingo Findenegg 《Aquatic Sciences - Research Across Boundaries》1966,28(2):148-172

Ohne Zusammenfassung  相似文献   

Dust on the Outskirts of the Jovian System     

Alexander V. Krivov  Ingo WardinskiFrank Spahn  Harald KrügerEberhard Grün 《Icarus》2002,157(2):436-455

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.  相似文献   

Petrologic and geochemical investigation of carbonates in peridotite xenoliths from northeastern Tanzania   总被引：5，自引：1，他引：4  

Cin-Ty Lee  Roberta L. Rudnick  William F. McDonough  Ingo Horn 《Contributions to Mineralogy and Petrology》2000,139(4):470-484

Primary carbonates in peridotite xenoliths from the East African Rift in northeastern Tanzania occur as intergranular patches with accessory minerals (olivine and spinel), as patches with accessory magmatic minerals (nepheline), and as round monomineralic inclusions in primary olivine grains. All are characterized by calcitic compositions (Ca/Ca + Mg + Fe from 0.83 to 0.99), extremely low SiO₂ + Al₂O₃ + Na₂O + K₂O, low trace element abundance [total rare-earth element (REE) abundance <25 ppm], uniform extinction, and lack of reaction textures with the host xenolith. Calculated Fe–Mg exchange coefficients between carbonate and primary olivine indicate disequilibrium in most samples. Combined with the lack of significant reaction textures, this suggests that the carbonates were introduced shortly before or during eruption of the host magma. A global compilation of electron microprobe analyses of mantle-derived carbonates (in xenoliths, xenocrysts, and megacrysts) reveals compositional clusters near end member calcite, end member magnesite, and stoichiometric dolomite. Eutectic liquid compositions are less common, suggesting that many carbonate inclusions reported worldwide may be crystalline precipitates. Likewise, the calcites in this study are not interpreted to represent quenched carbonatitic melts, but are interpreted instead to be crystalline cumulates from such melts. These inferences are consistent with recent experiments, which show that carbonatitic melts cannot become more calcitic than CaCO₃∼80 wt%. Low trace element abundance may be a diagnostic feature of cumulate carbonate, and in combination with petrography and major element composition, serve to distinguish it from quenched carbonated liquid. Received: 30 July 1999 / Accepted: 5 February 2000  相似文献   

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

Rainer Wieler  Anselmo Pedroni  Ingo Leya 《Meteoritics & planetary science》2000,35(2):251-257

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.  相似文献   

What controls equatorial Atlantic winds in boreal spring?     

Ingo Richter  Swadhin K. Behera  Takeshi Doi  Bunmei Taguchi  Yukio Masumoto  Shang-Ping Xie 《Climate Dynamics》2014,43(11):3091-3104

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.  相似文献