Comparison of Satellite-Only Gravity Field Models Constructed with All and Parts of the GOCE Gravity Gradient Dataset     

Sean L. Bruinsma  Christoph Förste  Sandrine Mulet  Marie-Hélène Rio  Oleg Abrikosov  Jean-Charles Marty 《Marine Geodesy》2016,39(3-4):238-255

The impact of GOCE Satellite Gravity Gradiometer data on gravity field models was tested. All models were constructed with the same Laser Geodynamics Satellite (LAGEOS) and Gravity Recovery and Climate Experiment (GRACE) data, which were combined with one or two of the diagonal gravity gradient components for the entire GOCE mission (November 2009 to October 2013). The Stokes coefficients were estimated by solving large normal equation (NE) systems (i.e., the direct numerical approach). The models were evaluated through comparisons with the European Space Agency's (ESA) gravity field model DIR-R5, by GPS/Leveling, GOCE orbit determination, and geostrophic current evaluations. Among the single gradient models, only the model constructed with the vertical ZZ gradients gave good results that were in agreement with the formal errors. The model based only on XX gradients is the least accurate. The orbit results for all models are very close and confirm this finding. All models constructed with two diagonal gradient components are more accurate than the ZZ-only model due to doubling the amount of data and having two complementary observation directions. This translates also to a slower increase of model errors with spatial resolution. The different evaluation methods cannot unambiguously identify the most accurate two-component model. They do not always agree, emphasizing the importance of evaluating models using many different methods. The XZ gravity gradient gives a small positive contribution to model accuracy.  相似文献   

Editorial     

T. L. Grove  J. Hoefs 《Contributions to Mineralogy and Petrology》2006,151(4):371-371

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Données cytologiques sur deux Cyanophycées:Spirulina platensis (Gom.) Geitler etSpirulina geitleri J. de Toni     

F. Marty  F. Busson 《Aquatic Sciences - Research Across Boundaries》1970,32(2):559-565

The interest of many research specialists is, at present, focused on twoSpirulina, which can be cultivated for alimentary purposes. Optimum conditions for industrial cultivation are known, but far more must be found out about the systematic position of the two microorganisms as well as their structural and metabolic biochemistry, since these facts are essential for more rational industrial use. This paper marks the beginning of a cytological and cytochemical research program.  相似文献   

Experimental investigations of the role of H2O in calc-alkaline differentiation and subduction zone magmatism   总被引：6，自引：3，他引：6  

T. W. Sisson  T. L. Grove 《Contributions to Mineralogy and Petrology》1993,113(2):143-166

Phase relations of natural aphyric high-alumina basalts and their intrusive equivalents were determined through rock-melting experiments at 2 kb, H₂O-saturated with fO₂ buffered at NNO. Experimental liquids are low-MgO high-alumina basalt or basaltic andesite, and most are saturated with olivine, calcic plagioclase, and either high-calcium pyroxene or hornblende (±magnetite). Cr-spinel or magnetite appear near the liquidus of wet high-alumina basalts because H₂O lowers the appearance temperature of crystalline silicates but has a lesser effect on spinel. As a consequence, experimental liquids follow calcalkaline differentiation trends. Hornblende stability is sensitive to the Na₂O content of the bulk composition as well as to H₂O content, with the result that hornblende can form as a near liquidus mineral in wet sodic basalts, but does not appear until liquids reach andesitic compositions in moderate Na₂O basalts. Therefore, the absence of hornblende in basalts with low-to-moderate Na₂O contents is not evidence that those basalts are nearly dry. Very calcic plagioclase (>An₉₀) forms from basaltic melts with high H₂O contents but cannot form from dry melts with normal are Na₂O and CaO abundances. The presence of anorthite-rich plagioclase in high-alumina basalts indicates high magmatic H₂O contents. In sum, moderate pressure H₂O-saturated phase relations show that magmatic H₂O leads to the early crystallization of spinel, produces calcic plagioclase, and reduces the total proportion of plagioclase in the crystallizing assemblage, thereby promoting the development of the calc-alkaline differentiation trend.  相似文献   

Corrections to expressions for calculating mineral components in “Origin of calc-alkaline series lavas at medicine lake volcano by fractionation,assimilation and mixing” and “Experimental petrology of normal MORB near the kane fracture zone: 22°-25°N,mid-atlantic ridge”     

Timothy L. Grove 《Contributions to Mineralogy and Petrology》1993,114(3):422-424

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Temperatures and H2O contents of low-MgO high-alumina basalts   总被引：1，自引：1，他引：1  

T. W. Sisson  T. L. Grove 《Contributions to Mineralogy and Petrology》1993,113(2):167-184

Experimental evidence is used to estimate H₂O contents in low-MgO high-alumina basalts (HABs) (<6 wt.% MgO) and basaltic andesites (BAs) (<5 wt.% MgO) that occur worldwide in magmatic arcs. Wholerock compositions of low-MgO HABs and BAs, phenocryst assemblages, and mineral chemistry match the compositions of liquids, phase assemblages, and mineral-compositions produced in H₂O-saturated melting experiments on HABs at moderate pressure (1–2 kb). Low-MgO HABs and BAs therefore could have existed as H₂O-rich multiply-saturated liquids within the crust. Results are presented for melting experiments on two HABs and an andesite at 1 kb pressure, H₂O-saturated, with fO₂ at the NNO buffer. These data and other experimental results on HABs are used to develop a method to estimate the temperature and H₂O content of HAB or BA liquids saturated with olivine, plagioclase, and either high-Ca pyroxene or hornblende. Estimated H₂O contents of HAB liquids are variable and range from 1 to 8 wt.%. High-MgO HABs (>8wt.% MgO) could have H₂O contents reaching no more than 1–2wt.%. The more common low-MgO HABs could have existed as liquids within the crust with H₂O contents of 4 wt.% or higher at temperatures<1100°C. Magmas with these high H₂O contents will saturate with and exsolve aqueous fluid upon approaching the surface. They cannot erupt as liquids and must grow crystals at shallow depths, thus accounting for the abundant phenocrysts in low-MgO HABs and BAs.  相似文献   

Methane sources,sinks and fluxes in a temperate tidal Lagoon: The Arcachon lagoon (SW France)     

Jonathan Deborde  Pierre Anschutz  Frédéric Guérin  Dominique Poirier  Danielle Marty  Guy Boucher  Gérard Thouzeau  Mathieu Canton  Gwenaël Abril 《Estuarine, Coastal and Shelf Science》2010

The Arcachon lagoon is a 156 km² temperate mesotidal lagoon dominated by tidal flats (66% of the surface area). The methane (CH₄) sources, sinks and fluxes were estimated from water and pore water concentrations, from chamber flux measurements at the sediment–air (low tide), sediment–water and water–air (high tide) interfaces, and from potential oxidation and production rate measurements in sediments. CH₄ concentrations in waters were maximal (500–1000 nmol l⁻¹) in river waters and in tidal creeks at low tide, and minimal in the lagoon at high tide (<50 nmol l⁻¹). The major CH₄ sources are continental waters and the tidal pumping of sediment pore waters at low tide. Methanogenesis occurred in the tidal flat sediments, in which pore water concentrations were relatively high (2.5–8.0 μmol l⁻¹). Nevertheless, the sediment was a minor CH₄ source for the water column and the atmosphere because of a high degree of anaerobic and aerobic CH₄ oxidation in sediments. Atmospheric CH₄ fluxes at high and low tide were low compared to freshwater wetlands. Temperate tidal lagoons appear to be very minor contributor of CH₄ to global atmosphere and to open ocean.  相似文献   

Incremental melting in the ureilite parent body: Initial composition,melting temperatures,and melt compositions     

Max Collinet  Timothy L. Grove 《Meteoritics & planetary science》2020,55(4):832-856

Ureilites are carbon‐rich ultramafic achondrites that have been heated above the silicate solidus, do not contain plagioclase, and represent the melting residues of an unknown planetesimal (i.e., the ureilite parent body, UPB). Melting residues identical to pigeonite‐olivine ureilites (representing 80% of ureilites) have been produced in batch melting experiments of chondritic materials not depleted in alkali elements relative to the Sun’s photosphere (e.g., CI, H, LL chondrites), but only in a relatively narrow range of temperature (1120 ºC–1180 ºC). However, many ureilites are thought to have formed at higher temperature (1200 ºC–1280 ºC). New experiments, described in this study, show that pigeonite can persist at higher temperature (up to 1280 ºC) when CI and LL chondrites are melted incrementally and while partial melts are progressively extracted. The melt productivity decreases dramatically after the exhaustion of plagioclase with only 5–9 wt% melt being generated between 1120 ºC and 1280 ºC. The relative proportion of pyroxene and olivine in experiments is compared to 12 ureilites, analyzed for this study, together with ureilites described in the literature to constrain the initial Mg/Si ratio of the UPB (0.98–1.05). Experiments are also used to develop a new thermometer based on the partitioning of Cr between olivine and low‐Ca pyroxene that is applicable to all ureilites. The equilibration temperature of ureilites increases with decreasing Al₂O₃ and Wo contents of pyroxene and decreasing bulk REE concentrations. The UPB melted incrementally, at different fO₂, and did not cool significantly (0 ºC–30 ºC) prior to its disruption. It remained isotopically heterogenous, but the initial concentration of major elements (SiO₂, MgO, CaO, Al₂O₃, alkali elements) was similar in the different mantle reservoirs.  相似文献   

Zero-difference GPS ambiguity resolution at CNES–CLS IGS Analysis Center     

Sylvain Loyer  Félix Perosanz  Flavien Mercier  Hugues Capdeville  Jean-Charles Marty 《Journal of Geodesy》2012,86(11):991-1003

CNES (Centre National d’Etudes Spatiales) and CLS (Collecte Localisation Satellites) became an International GNSS Service (IGS) Analysis Center (AC) the 20th of May 2010. Since 2009, we are using the integer ambiguity fixing at the zero-difference level strategy in our software package (GINS/Dynamo) as an alternative to classical differential approaches. This method played a key role among all the improvements in the GPS processing we made during this period. This paper provides to the users the theoretical background, the strategies and the models used to compute the products (GPS orbits and clocks, weekly station coordinate estimates and Earth orientation parameters) that are submitted weekly to the IGS. The practical realization of the two-step, ambiguity-fixing scheme (wide-lane and narrow-lane) is described in detail. The ambiguity fixing improved our orbit overlaps from 6 to 3?cm WRMS in the tangential and normal directions. Since 2008, our products have been also regularly compared to the IGS final solutions by the IGS Analysis Center Coordinator. The joint effects of ambiguity fixing and dynamical model changes (satellite solar radiation pressure and albedo force) improved the consistency with IGS orbits from 35 to 18?mm 3D-WRMS. Our innovative strategy also gives additional powerful properties to the GPS satellite phase clock solutions. Single receiver (zero-difference) ambiguity resolution becomes possible. An overview of the applications is given.  相似文献   

High Resolution DEM Generation in High‐Alpine Terrain Using Airborne Remote Sensing Techniques     

Yves Bühler  Mauro Marty  Christian Ginzler 《Transactions in GIS》2012,16(5):635-647

Up‐to‐date and accurate digital elevation models (DEMs) are essential for many applications such as numerical modeling of mass movements or mapping of terrain changes. Today the Federal Department of Topography, swisstopo, provides Digital Terrain Models (DTMs) and Digital Surface Models (DSMs) derived from airborne LiDAR data with a high spatial resolution of 2 m covering the entire area of Switzerland below an elevation of 2000 m a.s.l.. However, above an elevation of 2000 m a.s.l., which is typical for high‐alpine terrain, the best product available is the a DTM with a spatial resolution of 25 m. This spatial resolution is insufficient for many applications in complex terrain. In this study, we investigate the quality of DSMs derived from opto‐electronic scanner data (ADS80; acquired in autumn 2010) using photogrammetric image correlation techniques based on the multispectral nadir and backward looking sensor data. As reference, we take a high precision airborne LiDAR data set with a spatial resolution of ca. 0.5 m, acquired in late summer 2010, covering the Grabengufer/Dorfbach catchment near Randa, VS. We find the deviations between the two datasets are surprisingly low. In terrain with inclination angles of less than 30° the RMSE is below 0.5 m. In extremely steep terrain of more than 50° the RMSE goes up to 2 m and outliers increase significantly. We also find dependencies of the deviations on illumination conditions and ground cover classes. Finally we discuss advantages and disadvantages of the different data acquisition methods.  相似文献