GOCE gravitational gradiometry   总被引：16，自引：6，他引：10  

Reiner Rummel  Weiyong Yi  Claudia Stummer 《Journal of Geodesy》2011,85(11):777-790

GOCE is the first gravitational gradiometry satellite mission. Gravitational gradiometry is the measurement of the second derivatives of the gravitational potential. The nine derivatives form a 3 × 3 matrix, which in geodesy is referred to as Marussi tensor. From the basic properties of the gravitational field, it follows that the matrix is symmetric and trace free. The latter property corresponds to Laplace equation, which gives the theoretical foundation of its representation in terms of spherical harmonic or Fourier series. At the same time, it provides the most powerful quality check of the actual measured gradients. GOCE gradiometry is based on the principle of differential accelerometry. As the satellite carries out a rotational motion in space, the accelerometer differences contain angular effects that must be removed. The GOCE gradiometer provides the components V _xx , V _yy , V _zz and V _xz with high precision, while the components V _xy and V _yz are of low precision, all expressed in the gradiometer reference frame. The best performance is achieved inside the measurement band from 5 × 10^–3 to 0.1 Hz. At lower frequencies, the noise increases with 1/f and is superimposed by cyclic distortions, which are modulated from the orbit and attitude motion into the gradient measurements. Global maps with the individual components show typical patterns related to topographic and tectonic features. The maps are separated into those for ascending and those for descending tracks as the components are expressed in the instrument frame. All results are derived from the measurements of the period from November to December 2009. While the components V _xx and V _yy reach a noise level of about \({10\;\rm{\frac{mE}{\sqrt{Hz}}}}\), that of V _zz and V _xz is about \({20\; \rm{\frac{mE}{\sqrt{Hz}}}}\). The cause of the latter’s higher noise is not yet understood. This is also the reason why the deviation from the Laplace condition is at the \({20 \;\rm{\frac{mE}{\sqrt{Hz}}}}\) level instead of the originally planned \({11\;\rm{\frac{mE}{\sqrt{Hz}}}}\). Each additional measurement cycle will improve the accuracy and to a smaller extent also the resolution of the spherical harmonic coefficients derived from the measured gradients.  相似文献   

Nb–Ta fractionation by partial melting at the titanite–rutile transition     

Timm John  Reiner Klemd  Stephan Klemme  Jörg A. Pfänder  J. Elis Hoffmann  Jun Gao 《Contributions to Mineralogy and Petrology》2011,161(1):35-45

During the evolution of the Earth, distinct geochemical reservoirs with different Nb/Ta ratios have developed. Archean granitoids of the tonalite–trondhjemite–granodiorite (TTG) suite, which represent the Earth’s early continental crust, show larger Nb/Ta variations than any other Earth reservoir. This implies that significant Nb–Ta fractionation must have occurred during early crust formation, while the underlying mechanism behind is still unclear. Here, we present a new model on how Nb may be fractionated from Ta during partial melting of subducted oceanic crust. Our data show that Nb/Ta ratios in melts derived from rutile- and titanite-bearing eclogite are largely controlled by the modal relative abundances of rutile and titanite in the source. High modal ratios of titanite over rutile generate melts with very high Nb/Ta (>60), whereas low modal titanite/rutile produces melts with much lower Nb/Ta (≤30). Very low Nb/Ta (<16) occur when all Ti-phases are consumed at very high degrees of melting. As the modal ratio of titanite to rutile is a function of pressure, the Nb/Ta of melts is a function of melting depth. Our new model helps to explain the extreme variation of Nb/Ta observed in many TTGs and thus how Nb and Ta were fractionated during the early evolution of the Earth. Furthermore, the model also indicates that simple one-stage melting models for mafic crust are not sufficient to explain the formation of TTGs.  相似文献   

Weathering of Fruchtschiefer building stones: mineral dissolution or rock disaggregation?     

Cornelius Fischer  Stephan Kaufhold  Wanja Wedekind  Reiner Dohrmann  Volker Karius  Siegfried Siegesmund 《Environmental Earth Sciences》2011,63(7-8):1665-1676

Building stones manufactured from contact metamorphic slates (Fruchtschiefer slate) from Theuma (Sachsen, Germany) were investigated for mineralogical alterations as well as for changes in porosity and surface roughness due to weathering. After weathering periods of several years to decades, the originally dark gray-colored slates show pale spots of several centimeters in size at the surface of building stones. The dark-colored and light-colored sections of the slate show no differences in mineralogy. Surface weathering did not result in newly precipitated minerals. It was also found that the observed differences in color are not caused by variations in sedimentary organic carbon concentration or in sulfide/sulfate concentrations. Obtained results instead indicate that dark surface sections may show a thin cover of recent organic matter (OM), e.g., living OM, soot, dirt, etc. Microscopic investigations suggested that this cover was exfoliated at light-colored surface sections. The observed disaggregation of the upper 2 mm of the building block material results in an increase in porosity. Porosity of black (unweathered) slate is <2 vol.%. Due to weathering, the slate’s pores with diameters >1 μm show a significant increase in frequency compared to the original pore size distribution. Porosity of weathered rock volumes increased to approx. 8 vol.%. Discolored surface sections show a higher surface roughness (root-mean-square roughness, Rq ~ 1 μm) compared to dark-colored slate surfaces (Rq ~ 200 nm), both data are for cleavage planes. Preferentially, the discolored surface sections are located close to the edges of cut stones. This and the alteration in porosity, pore size, and surface roughness indicate that color changes of the slate are largely influenced by rock disaggregation proceeding from the edges into the center rather than by mineral dissolution/precipitation processes.  相似文献   

On the spectral consistency of the altimetric ocean and geoid surface: a one-dimensional example     

Alberta Albertella  Reiner Rummel 《Journal of Geodesy》2009,83(9):805-815

Geoid models from the new generation of satellite gravity missions, such as GRACE and GOCE, in combination with sea surface from satellite altimetry allow to obtain absolute dynamic ocean topography with rather high spatial resolution and accuracy. However, this implies combination of data with fundamentally different characteristics and different spatial resolutions. Spectral consistency would imply the removal of the short-scale features of the altimetric sea surface height by filtering, to provide altimetric data consistent with the resolution of the geoid field. The goal must be to lose as little as possible from the high precision of the altimetric signal. Using a one-dimensional example we show how the spectrum is changing when a function defined only on a limited domain (ocean in the real case) is extended or not as to cover the complete domain (the whole sphere in the real case). The results depend on the spectral characteristics of the altimetric signal and of the applied filter. Referring to the periodicity condition, as it is requested in the case of Fourier analysis, the action of the two classical filters (Ideal Low Pass and Gauss filter) and of two alternative procedures (wavelets and Slepian) is studied.  相似文献   

The evolution of stars and gas in starburst galaxies     

Roberto Cid Fernandes  João R. S. Leão  Reiner Rodrigues Lacerda 《Monthly notices of the Royal Astronomical Society》2003,340(1):29-42

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A combined IR and XRD study of natural well crystalline goethites (α-FeOOH)     

Kaufhold  Stephan  Ufer  Kristian  Hein  Melanie  Götze  Niko  Dohrmann  Reiner 《中国地球化学学报》2022,41(5):794-810

Acta Geochimica - Goethite (α-FeOOH) is one of the most abundant minerals on the Earth surface, occurring in temperate, tropical and equatorial climates. Fe in goethite can be substituted by...  相似文献   

德国4站点极端降水频数和强度趋势变化分析   总被引：1，自引：0，他引：1  

杨靖文  孙即霖  Reiner Schlitzer 《中国海洋大学学报(自然科学版)》2010,(Z1)

根据不莱梅、波茨坦、卡尔斯鲁厄和楚格峰1901—2007年逐日降水量分析了各站极端降水的频数和强度趋势变化。结果表明:山区(楚格峰)出现的极端降水数量呈上升趋势,且强度显著增强,在冬、夏2季亦如此。这与全球变暖背景下,山区的积雪融化导致对流活动增强以及大气环流影响水汽输送增强有关;在超过绝对阈值的极端降水方面,北方地区(不莱梅和波茨坦)发生频数保持稳定,无显著趋势变化,南方地区(卡尔斯鲁厄)有显著减少的趋势,且不莱梅的频数变化趋势与波茨坦相似,具有强正相关,而此2站与卡尔斯鲁厄的频数变化趋势呈反位相,有较强的负相关;除楚格峰外,极端降水强度变化无显著趋势。低海拔地区在冬季极端降水的频数和强度上,大部分有显著上升的趋势,而夏季,在2方面均出现不同程度的下降;极端降水频数和强度呈强正相关。  相似文献   

The Moho Structure in The Western Eger Rift: A Receiver Function Experiment     

Geissler  Wolfram  Plenefisch  Thomas  Kind  Reiner  Klinge  Klaus  Kämpf  Horst  Boušková  Alena  Nehybka  Vladimír  Skácelová  Zuzana  Jacob  Brian 《Studia Geophysica et Geodaetica》2000,44(2):188-194

We used teleseismic recordings of a temporary deployment of seismic stations and of permanent short period stations in the western Eger Rift system to study the lithosphere with the help of Receiver Functions. The crust-mantle boundary (Moho) is observed at almost all stations by strong P-to-S converted phases. The Moho is basically flat between about 26 – 30 km depth in the entire region. At one station in the Eger Rift (BOH-1, Loket castle) no Moho is observed. We interpret this with the existence of a broad gradient zone there, instead of a sharp discontinuity. This observation, however, needs to be confirmed by more data.  相似文献   

Stef Proost and John B. Braden (eds.), Climate Change, Transport and Environmental Policy     

David Reiner  Andreas Schafer 《Climatic change》2000,47(1-2):217-224

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Stabilization and global climate policy   总被引：1，自引：0，他引：1  

Marcus C. Sarofim  Chris E. Forest  David M. Reiner  John M. Reilly 《Global and Planetary Change》2005,47(2-4):266

Academic and political debates over long-run climate policy often invoke “stabilization” of atmospheric concentrations of greenhouse gases (GHGs), but only rarely are non-CO₂ greenhouse gases addressed explicitly. Even though the majority of short-term climate policies propose trading between gases on a global warming potential (GWP) basis, discussions of whether CO₂ concentrations should be 450, 550, 650 or perhaps as much as 750 ppm leave unstated whether there should be no additional forcing from other GHGs beyond current levels or whether separate concentration targets should be established for each GHG. Here, we use an integrated modeling framework to examine multi-gas stabilization in terms of temperature, economic costs, carbon uptake and other important consequences. We show that there are significant differences in both costs and climate impacts between different “GWP equivalent” policies and demonstrate the importance of non-CO₂ GHG reduction on timescales of up to several centuries.  相似文献