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Littérature scientifique sur le sujet « Gravity variations »

Auteur : Grafiati
Publié le 10 mars 2023

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Articles de revues sur le sujet "Gravity variations"

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Kumari, Pooja, V. Raghunandan et P. Biswal. « Diurnal variation in aviation significant gravity-dependent and gravity-independent anthropometric parameters ». Indian Journal of Aerospace Medicine 65 (6 août 2021) : 5–9. http://dx.doi.org/10.25259/ijasm_61_2020.

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Introduction: Anthropometric parameters need to be accurately measured because of their direct implications in selection of aircrew, aircrew-cockpit compatibility, and cockpit workspace design. Some of these parameters have significant diurnal variation, hence, measurement of these parameters in particular time of day becomes important. Quantification of these diurnal variations among some of the aviation significant parameters was the desired objective of the study. Material and Methods: In a prospective repeated measure design, anthropometric parameters of a total of 35 volunteers were measured in the standard defined protocol from 0800h to 1600h, at an interval of every 2h, using Institute of Aerospace Medicine (IAM) Anthropometry Platform. The data were analyzed to observe and quantify changes in diurnal variations in both gravity-dependent and gravity-independent parameters. A maximum value of 0.4 cm was taken as intraobserver variations based on the results of a pilot study. Results: There was a statistically significant decrement in the values of gravity-dependent anthropometric parameters from morning to evening; the difference being more after 1200h. Most of the gravity-independent parameters did not show any significant changes from 0800h to 1600h, except leg length, which showed a decrement overtime, the difference being statistically significant after 1200h. Conclusion: The study revealed a statistically significant variation of gravity-dependent anthropometric parameters from the baseline which could be because of the effect of erect posture on the intervertebral disc height and axial compressive loads on the spine. This became practically significant after 1200h. However, most of the gravity-independent parameters did not show any significant variations. Based on the results of this study, anthropometric measurements should be done in the morning hours preferably before 1200h.
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LaFehr, T. R. « Standardization in gravity reduction ». GEOPHYSICS 56, no 8 (août 1991) : 1170–78. http://dx.doi.org/10.1190/1.1443137.

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Gravity reduction standards are needed to improve anomaly quality for interpretation and to facilitate the joining together of different data sets. To the extent possible, data reduction should be quantitative, objective, and comprehensive, leaving ambiguity only to the interpretation process that involves qualitative, subjective, and geological decisions. The term (Bouguer anomaly) describes a field intended to be free of all nongeologic effects—not modified by a partial geologic interpretation. Measured vertical gradients of gravity demonstrate considerable variation but do not suggest, as often reported, that the normal free‐air gradient is in error or needs to be locally adjusted. Such gradients are strongly influenced by terrain and, to a lesser extent, by the same geologic sources which produce Bouguer anomalies. A substantial body of existing literature facilitates the comprehensive treatment of terrain effects, which may be rigorously implemented with current computer technology. Although variations in topographic rock density are a major source of Bouguer anomalies, a constant density appropriate to the area under investigation is normally adopted as a data reduction standard, leaving a treatment of the density variations to the interpretation. A field example from British Columbia illustrates both the variations in vertical gravity gradients which can be encountered and the conclusion that the classical approach to data reduction is practically always suitable to account for the observed effects. Standard data reduction procedures do not (and should not) include reduction‐to‐datum. The interpreter must be aware, however, that otherwise “smooth” regional Bouguer anomalies caused by regional sources do contain high‐frequency components in areas of rugged topography.
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Dumberry, Mathieu. « Gravity variations induced by core flows ». Geophysical Journal International 180, no 2 (février 2010) : 635–50. http://dx.doi.org/10.1111/j.1365-246x.2009.04437.x.

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Kuo, John T., et Sun Yue-Feng. « Modeling gravity variations caused by dilatancies ». Tectonophysics 227, no 1-4 (novembre 1993) : 127–43. http://dx.doi.org/10.1016/0040-1951(93)90091-w.

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Clemesha, B. R., P. P. Batista, R. A. Buriti da Costa et N. Schuch. « Seasonal variations in gravity wave activity at three locations in Brazil ». Annales Geophysicae 27, no 3 (4 mars 2009) : 1059–65. http://dx.doi.org/10.5194/angeo-27-1059-2009.

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Abstract. Using the variance in meteor radar winds as a measure of gravity wave activity, we investigate the temporal variations in gravity waves at three locations in Brazil: São João do Cariri (7.3° S, 36.4° W), Cachoeira Paulista (22.7° S, 45.0° W) and Santa Maria (29.7° S, 53.7° W). The technique used is that of Hocking (2005) which makes it possible to separate the zonal and meridional components of the fluctuating wind velocity. We find that the seasonal variation of the fluctuating wind is similar to that of the amplitude of the diurnal tide, showing a predominantly semi-annual variation, stronger at Cachoeira Paulista and Santa Maria than at the quasi-equatorial station, Cariri. Both with respect to the seasonal trend and shorter term variations, strong coupling between gravity wave activity and tides is indicated by a remarkably close correlation between the fluctuating velocity and the vertical shear in the tidal winds. It is not clear as to whether this is caused by gravity wave forcing of the tides or whether it results from in situ generation of gravity waves by tidal wind shear.
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Journal, Baghdad Science. « Gravity Field Interpretation for Major Fault Depth Detection in a Region Located SW- Qa’im / Iraq ». Baghdad Science Journal 14, no 3 (3 septembre 2017) : 625–36. http://dx.doi.org/10.21123/bsj.14.3.625-636.

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This research deals with the qualitative and quantitative interpretation of Bouguer gravity anomaly data for a region located to the SW of Qa’im City within Anbar province by using 2D- mapping methods. The gravity residual field obtained graphically by subtracting the Regional Gravity values from the values of the total Bouguer anomaly. The residual gravity field processed in order to reduce noise by applying the gradient operator and 1st directional derivatives filtering. This was helpful in assigning the locations of sudden variation in Gravity values. Such variations may be produced by subsurface faults, fractures, cavities or subsurface facies lateral variations limits. A major fault was predicted to extend with the direction NE-SW. This fault is mentioned by previous studies as undefined subsurface fault depth within the sedimentary cover rocks. The results of this research that were obtained by gravity quantitative interpretation find that the depth to this major fault plane center is about 2.4 Km.
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Ruggiero, Matteo Luca. « Perturbations of Keplerian orbits in stationary spherically symmetric spacetimes ». International Journal of Modern Physics D 23, no 05 (30 avril 2014) : 1450049. http://dx.doi.org/10.1142/s0218271814500497.

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We study spherically symmetric perturbations determined by alternative theories of gravity to the gravitational field of a central mass in General Relativity (GR). In particular, we focus on perturbations in the form of power laws and calculate their effect on the secular variations of the orbital elements of a Keplerian orbit. We show that, to lowest approximation order, only the argument of pericenter and mean anomaly undergo secular variations; furthermore, we calculate the variation of the orbital period. We give analytic expressions for these variations which can be used to constrain the impact of alternative theories of gravity.
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Földváry, Lorant, Victor Statov et Nizamatdin Mamutov. « Applicability of GRACE and GRACE-FO for monitoring water mass changes of the Aral Sea and the Caspian Sea ». InterCarto. InterGIS 26, no 2 (2020) : 443–53. http://dx.doi.org/10.35595/2414-9179-2020-2-26-443-453.

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The GRACE gravity satellite mission has provided monthly gravity field solutions for about 15 years enabling a unique opportunity to monitor large scale mass variation processes. By the end of the GRACE, the GRACE-FO mission was launched in order to continue the time series of monthly gravity fields. The two missions are similar in most aspects apart from the improved intersatellite range rate measurements, which is performed with lasers in addition to microwaves. An obvious demand for the geoscientific applications of the monthly gravity field models is to understand the consistency of the models provided by the two missions. This study provides a case-study related consistency investigation of GRACE and GRACE-FO monthly solutions for the Aral Sea region. As the closeness of the Caspian Sea may influence the monthly mass variations of the Aral Sea, it has also been involved in the investigations. According to the results, GRACE-FO models seem to continue the mass variations of the GRACE period properly, therefore their use jointly with GRACE is suggested. Based on the justified characteristics of the gravity anomaly by water volume variations in the case of the Aral Sea, GRACE models for the period March–June 2017 are suggested to be neglected. Though the correlation between water volume and monthly gravity field variations is convincing in the case of the Aral Sea, no such a correlation for the Caspian Sea could have been detected, which suggests to be the consequence of other mass varying processes, may be related to the seismicity of the Caspian Sea area.
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Ridley, Kevin. « Modelling the Gravitational Effects of Random Underground Density Variations ». Mathematical Geosciences 52, no 6 (9 octobre 2019) : 759–81. http://dx.doi.org/10.1007/s11004-019-09827-3.

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Abstract A mathematical model for small-scale spatial variations in gravity above the Earth’s surface is presented. Gravity variations are treated as a Gaussian random process arising from underground density variations which are assumed to be a Gaussian random process. Expressions for two-point spatial statistics are calculated for both the vertical component of gravity and the vertical gradient of the vertical component. Results are given for two models of density variations: a delta-correlated model and a fractal model. The effect of an outer scale in the fractal model is investigated. It is shown how the results can be used to numerically generate realisations of gravity variations with fractal properties. Such numerical modelling could be useful for investigating the feasibility of using gravity surveys to locate and characterise underground structures; this is explored through the simple example of a tunnel detection scenario.
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Goodkind, John M. « Continuous measurement of nontidal variations of gravity ». Journal of Geophysical Research 91, B9 (1986) : 9125. http://dx.doi.org/10.1029/jb091ib09p09125.

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Thèses sur le sujet "Gravity variations"

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Alothman, Abdulaziz. « Temporal variations of the earth's gravity field from GPS and SLR ». Thesis, University of Newcastle Upon Tyne, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.405083.

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Berkel, Paula. « Multiscale methods for the combined inversion of normal mode and gravity variations ». Aachen Shaker, 2009. http://d-nb.info/997085304/04.

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Anjasmara, Ira Mutiara. « Spatio-temporal analysis of GRACE gravity field variations using the principal component analysis ». Thesis, Curtin University, 2008. http://hdl.handle.net/20.500.11937/957.

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Gravity Recovery and Climate Experiment (GRACE) mission has amplified the knowledge of both static and time-variable part of the Earth’s gravity field. Currently, GRACE maps the Earth’s gravity field with a near-global coverage and over a five year period, which makes it possible to apply statistical analysis techniques to the data. The objective of this study is to analyse the most dominant spatial and temporal variability of the Earth’s gravity field observed by GRACE using a combination of analytical and statistical methods such as Harmonic Analysis (HA) and Principal Component Analysis (PCA). The HA is used to gain general information of the variability whereas the PCA is used to find the most dominant spatial and temporal variability components without having to introduce any presetting. The latter is an important property that allows for the detection of anomalous or a-periodic behaviour that will be useful for the study of various geophysical processes such as the effect from earthquakes. The analyses are performed for the whole globe as well as for the regional areas of: Sumatra- Andaman, Australia, Africa, Antarctica, South America, Arctic, Greenland, South Asia, North America and Central Europe. On a global scale the most dominant temporal variation is an annual signal followed by a linear trend. Similar results mostly associated to changing land hydrology and/or snow cover are obtained for most regional areas except over the Arctic and Antarctic where the secular trend is the prevailing temporal variability.Apart from these well-known signals, this contribution also demonstrates that the PCA is able to reveal longer periodic and a-periodic signal. A prominent example for the latter is the gravity signal of the Sumatra-Andaman earthquake in late 2004. In an attempt to isolate these signals, linear trend and annual signal are removed from the original data and the PCA is once again applied to the reduced data. For a complete overview of these results the most dominant PCA modes for the global and regional gravity field solutions are presented and discussed.
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Anjasmara, Ira Mutiara. « Spatio-temporal analysis of GRACE gravity field variations using the principal component analysis ». Curtin University of Technology, Department of Spatial Sciences, 2008. http://espace.library.curtin.edu.au:80/R/?func=dbin-jump-full&object_id=18720.

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Gravity Recovery and Climate Experiment (GRACE) mission has amplified the knowledge of both static and time-variable part of the Earth’s gravity field. Currently, GRACE maps the Earth’s gravity field with a near-global coverage and over a five year period, which makes it possible to apply statistical analysis techniques to the data. The objective of this study is to analyse the most dominant spatial and temporal variability of the Earth’s gravity field observed by GRACE using a combination of analytical and statistical methods such as Harmonic Analysis (HA) and Principal Component Analysis (PCA). The HA is used to gain general information of the variability whereas the PCA is used to find the most dominant spatial and temporal variability components without having to introduce any presetting. The latter is an important property that allows for the detection of anomalous or a-periodic behaviour that will be useful for the study of various geophysical processes such as the effect from earthquakes. The analyses are performed for the whole globe as well as for the regional areas of: Sumatra- Andaman, Australia, Africa, Antarctica, South America, Arctic, Greenland, South Asia, North America and Central Europe. On a global scale the most dominant temporal variation is an annual signal followed by a linear trend. Similar results mostly associated to changing land hydrology and/or snow cover are obtained for most regional areas except over the Arctic and Antarctic where the secular trend is the prevailing temporal variability.
Apart from these well-known signals, this contribution also demonstrates that the PCA is able to reveal longer periodic and a-periodic signal. A prominent example for the latter is the gravity signal of the Sumatra-Andaman earthquake in late 2004. In an attempt to isolate these signals, linear trend and annual signal are removed from the original data and the PCA is once again applied to the reduced data. For a complete overview of these results the most dominant PCA modes for the global and regional gravity field solutions are presented and discussed.
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KARIYAWASAM, THARANGA MANOHARI. « Theoretical Analysis of the Temperature Variations and the Krassovsky Ratio for Long Period Gravity Waves ». University of Cincinnati / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1212176032.

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Berkel, Paula [Verfasser]. « Multiscale Methods for the Combined Inversion of Normal Mode and Gravity Variations / Paula Berkel ». Aachen : Shaker, 2009. http://d-nb.info/1159835357/34.

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Prevost, Paoline. « Extraction des variations spatio-temporelles du champ de gravité à partir des données de la mission spatiale GRACE : méthodes et applications géophysiques ». Thesis, Paris Sciences et Lettres (ComUE), 2019. http://www.theses.fr/2019PSLEE017.

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L’estimation des variations spatio-temporelles du champ de gravité terrestre à partir des mesures de la mission satellitaire Gravity Recovery and Climate Experiment (GRACE) ont permis de mieux comprendre les redistributions de masse à des échelles de temps mensuelle, saisonnière ou décennale. Les solutions GRACE produites par différents centres, adoptant des stratégies de traitement différentes, conduisent à des résultats cohérents. Cependant, ces solutions présentent aussi des erreurs aléatoires et systématiques, celles-ci pouvant avoir une structure spatio-temporelle spécifique. Afin de réduire le bruit et améliorer la qualité des signaux géophysiques présents dans les données GRACE, plusieurs méthodes ont été proposées mais nécessitent en général des informations a priori sur la structure spatio-temporelle du bruit pourtant mal connue. Malgré les efforts considérables effectués pour améliorer la qualité des données GRACE pour des applications géophysiques de plus en plus fines, le filtrage du bruit reste une question problématique comme exposé dans le Chapitre 1. Dans cette thèse, nous proposons une approche différente, utilisant une technique de filtrage spatio-temporel, la Multichannel Singular Spectrum Analysis (M-SSA) décrite dans le Chapitre 2. La M-SSA est une méthode s’adaptant aux données, à variables multiples et non-paramétrique, qui exploite simultanément les corrélations spatiales et temporelles d’un champ géophysique. Nous utilisons la M-SSA sur 13 ans de données GRACE en harmoniques sphériques distribuées par cinq centres de calculs. Nous montrons que cette méthode permet d’extraire les modes de variabilité communs aux différentes solutions, et de réduire significativement les erreurs spatio-temporelles spécifiques à chaque solution et liées aux différentes stratégies de calculs. En particulier, cette méthode filtre efficacement les stries Nord-Sud dues, entre autres, aux imperfections des modèles de corrections des phénomènes connus. Dans le Chapitre 3, nous comparons notre solution GRACE à d’autres solutions en harmoniques sphériques et à des solutions basées sur des blocs de concentration de masse (mascons) utilisant des a priori sur la structure spatio-temporelle du signal géophysique. Nous comparons également les performances de notre solution M-SSA GRACE par rapport à d’autres solutions en calculant la déformation de surface induite par les variations de masse déduites des mesures GRACE et en la comparant avec des mesures indépendantes de déplacement provenant des stations du Global Navigation Satellite System (GNSS). Enfin, nous discutons dans le Chapitre 4 d’une application possible d’une solution GRACE améliorée pour répondre à des questions encore débattues liées au rebond post-glaciaire. Plus précisément, nous nous intéressons à la séparation du signal du rebond post-glaciaire, lié à la fonte ancienne, du signal de fonte récente des glaces dans la région de la Géorgie du Sud
Measurements of the spatio-temporal variations of Earth’s gravity field recovered from the Gravity Recovery and Climate Experiment (GRACE) mission have led to unprecedented insights into large spatial mass redistribution at secular, seasonal, and sub-seasonal time scales. GRACE solutions from various processing centers, while adopting different processing strategies, result in rather coherent estimates. However, these solutions also exhibit random as well as systematic errors, with specific spatial and temporal patterns in the latter. In order to dampen the noise and enhance the geophysical signals in the GRACE data, several methods have been proposed. Among these, methods based on filtering techniques require a priori assumptions regarding the spatio-temporal structure of the errors. Despite the large effort to improve the quality of GRACE data for always finer geophysical applications, removing noise remains a problematic question as discussed in Chapter 1. In this thesis, we explore an alternative approach, using a spatio-temporal filter, namely the Multichannel Singular Spectrum Analysis (M-SSA) described in Chapter 2. M-SSA is a data-adaptive, multivariate, and non-parametric method that simultaneously exploits the spatial and temporal correlations of geophysical fields to extract common modes of variability. We perform an M-SSA simultaneously on 13 years of GRACE spherical harmonics solutions from five different processing centers. We show that the method allows for the extraction of common modes of variability between solutions, and removal of the solution-specific spatio-temporal errors arising from each processing strategies. In particular, the method filters out efficiently the spurious North-South stripes, most likely caused by aliasing of the imperfect geophysical correction models of known phenomena. In Chapter 3, we compare our GRACE solution to other spherical harmonics solutions and to mass concentration (mascon) solutions which use a priori information on the spatio-temporal pattern of geophysical signals. We also compare performance of our M-SSA GRACE solution with respect to others by predicting surface displacements induced by GRACE-derived mass loading and comparing results with independent displacement data from stations of the Global Navigation Satellite System (GNSS). Finally, in Chapter 4 we discuss the possible application of a refined GRACE solution to answer debated post-glacial rebound questions. More precisely, we focus on separating the post-glacial rebound signal related to past ice melting and the present ice melting in the region of South Georgia
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Werth, Susanna. « Calibration of the global hydrological model WGHM with water mass variations from GRACE gravity data ». Phd thesis, Universität Potsdam, 2010. http://opus.kobv.de/ubp/volltexte/2010/4173/.

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Since the start-up of the GRACE (Gravity Recovery And Climate Experiment) mission in 2002 time dependent global maps of the Earth's gravity field are available to study geophysical and climatologically-driven mass redistributions on the Earth's surface. In particular, GRACE observations of total water storage changes (TWSV) provide a comprehensive data set for analysing the water cycle on large scales. Therefore they are invaluable for validation and calibration of large-scale hydrological models as the WaterGAP Global Hydrology Model (WGHM) which simulates the continental water cycle including its most important components, such as soil, snow, canopy, surface- and groundwater. Hitherto, WGHM exhibits significant differences to GRACE, especially for the seasonal amplitude of TWSV. The need for a validation of hydrological models is further highlighted by large differences between several global models, e.g. WGHM, the Global Land Data Assimilation System (GLDAS) and the Land Dynamics model (LaD). For this purpose, GRACE links geodetic and hydrological research aspects. This link demands the development of adequate data integration methods on both sides, forming the main objectives of this work. They include the derivation of accurate GRACE-based water storage changes, the development of strategies to integrate GRACE data into a global hydrological model as well as a calibration method, followed by the re-calibration of WGHM in order to analyse process and model responses. To achieve these aims, GRACE filter tools for the derivation of regionally averaged TWSV were evaluated for specific river basins. Here, a decorrelation filter using GRACE orbits for its design is most efficient among the tested methods. Consistency in data and equal spatial resolution between observed and simulated TWSV were realised by the inclusion of all most important hydrological processes and an equal filtering of both data sets. Appropriate calibration parameters were derived by a WGHM sensitivity analysis against TWSV. Finally, a multi-objective calibration framework was developed to constrain model predictions by both river discharge and GRACE TWSV, realised with a respective evolutionary method, the ε-Non-dominated-Sorting-Genetic-Algorithm-II (ε-NSGAII). Model calibration was done for the 28 largest river basins worldwide and for most of them improved simulation results were achieved with regard to both objectives. From the multi-objective approach more reliable and consistent simulations of TWSV within the continental water cycle were gained and possible model structure errors or mis-modelled processes for specific river basins detected. For tropical regions as such, the seasonal amplitude of water mass variations has increased. The findings lead to an improved understanding of hydrological processes and their representation in the global model. Finally, the robustness of the results is analysed with respect to GRACE and runoff measurement errors. As a main conclusion obtained from the results, not only soil water and snow storage but also groundwater and surface water storage have to be included in the comparison of the modelled and GRACE-derived total water budged data. Regarding model calibration, the regional varying distribution of parameter sensitivity suggests to tune only parameter of important processes within each region. Furthermore, observations of single storage components beside runoff are necessary to improve signal amplitudes and timing of simulated TWSV as well as to evaluate them with higher accuracy. The results of this work highlight the valuable nature of GRACE data when merged into large-scale hydrological modelling and depict methods to improve large-scale hydrological models.
Das Schwerefeld der Erde spiegelt die Verteilung von Massen auf und unter der Erdoberfläche wieder. Umverteilungen von Erd-, Luft- oder Wassermassen auf unserem Planeten sind damit über eine kontinuierliche Vermessung des Erdschwerefeldes beobachtbar. Besonders Satellitenmissionen sind hierfür geeignet, da deren Umlaufbahn durch zeitliche und räumliche Veränderung der Schwerkraft beeinflusst wird. Seit dem Start der Satellitenmission GRACE (Gravity Recovery And Climate Experiment) im Jahr 2002 stellt die Geodäsie daher globale Daten von zeitlichen Veränderungen des Erdschwerefeldes mit hoher Genauigkeit zur Verfügung. Mit diesen Daten lassen sich geophysikalische und klimatologische Massenumverteilungen auf der Erdoberfläche studieren. GRACE liefert damit erstmals Beobachtungen von Variationen des gesamten kontinentalen Wasserspeichers, welche außerordentlich wertvoll für die Analyse des Wasserkreislaufes über große Regionen sind. Die Daten ermöglichen die Überprüfung von großräumigen mathematischen Modellen der Hydrologie, welche den natürlichen Kreislauf des Wassers auf den Kontinenten, vom Zeitpunkt des Niederschlags bis zum Abfluss in die Ozeane, nachvollziehbar machen. Das verbesserte Verständnis über Transport- und Speicherprozesse von Süßwasser ist für genauere Vorhersagen über zukünftige Wasserverfügbarkeit oder potentielle Naturkatastrophen, wie z.B. Überschwemmungen, von enormer Bedeutung. Ein globales Modell, welches die wichtigsten Komponenten des Wasserkreislaufes (Boden, Schnee, Interzeption, Oberflächen- und Grundwasser) berechnet, ist das "WaterGAP Global Hydrology Model" (WGHM). Vergleiche von berechneten und beobachteten Wassermassenvariationen weisen bisher insbesondere in der jährlichen Amplitude deutliche Differenzen auf. Sehr große Unterschiede zwischen verschiedenen hydrologischen Modellen betonen die Notwendigkeit, deren Berechnungen zu verbessern. Zu diesem Zweck verbindet GRACE die Wissenschaftsbereiche der Geodäsie und der Hydrologie. Diese Verknüpfung verlangt von beiden Seiten die Entwicklung geeigneter Methoden zur Datenintegration, welche die Hauptaufgaben dieser Arbeit darstellten. Dabei handelt es sich insbesondere um die Auswertung der GRACE-Daten mit möglichst hoher Genauigkeit sowie um die Entwicklung einer Strategie zur Integration von GRACE Daten in das hydrologische Modell. Mit Hilfe von GRACE wurde das Modell neu kalbriert, d.h. Parameter im Modell so verändert, dass die hydrologischen Berechnungen besser mit den GRACE Beobachtungen übereinstimmen. Dabei kam ein multikriterieller Kalibrieralgorithmus zur Anwendung mit dem neben GRACE-Daten auch Abflussmessungen einbezogen werden konnten. Die Modellkalibierung wurde weltweit für die 28 größten Flusseinzugsgebiete durchgeführt. In den meisten Fällen konnte eine verbesserte Berechnung von Wassermassenvariationen und Abflüssen erreicht werden. Hieraus ergeben sich, z.B. für tropische Regionen, größere saisonale Variationen. Die Ergebnisse führen zu einem verbesserten Verständnis hydrologischer Prozesse. Zum Schluss konnte die Robustheit der Ergebnisse gegenüber Fehlern in GRACE- und Abflussmessungen erfolgreich getestet werden. Nach den wichtigsten Schlussfolgerungen, die aus den Ergebnissen abgeleitet werden konnten, sind nicht nur Bodenfeuchte- und Schneespeicher, sondern auch Grundwasser- und Oberflächenwasserspeicher in Vergleiche von berechneten und GRACE-beobachteten Wassermassenvariationen einzubeziehen. Weiterhin sind neben Abflussmessungen zusätzlich Beobachtungen von weiteren hydrologischen Prozessen notwendig, um die Ergebnisse mit größerer Genauigkeit überprüfen zu können. Die Ergebnisse dieser Arbeit heben hervor, wie wertvoll GRACE-Daten für die großräumige Hydrologie sind und eröffnen eine Methode zur Verbesserung unseres Verständnisses des globalen Wasserkreislaufes.
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Lorant, Foldvary. « Geoid Height Variations Caused by Geophysical Fluids and Their Possible Recovery by Future Satellite Gravity Missions ». 京都大学 (Kyoto University), 2001. http://hdl.handle.net/2433/150837.

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Elsaka, Basem [Verfasser]. « Simulated satellite formation flights for detecting the temporal variations of the Earth's gravity field / Basem Elsaka ». Bonn : Universitäts- und Landesbibliothek Bonn, 2019. http://d-nb.info/1199005320/34.

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Livres sur le sujet "Gravity variations"

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Rapp, Richard H., Anny A. Cazenave et R. Steven Nerem, dir. Global Gravity Field and Its Temporal Variations. Berlin, Heidelberg : Springer Berlin Heidelberg, 1996. http://dx.doi.org/10.1007/978-3-642-61140-7.

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H, Rapp Richard, Cazenave Anny et Nerem R. Steven 1960-, dir. Global gravity field and its temporal variations : Symposium no. 116, Boulder, CO, USA, July 12, 1995. Berlin : Springer, 1996.

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Toh, Hiroaki. Anomalies of geomagnetic and geoelectric variations at the seafloor around the Izu-Ogasawara Arc. Nakano-ku, Tokyo : Ocean Research Institute, University of Tokyo, 1995.

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Langenheim, Victoria E. Gravity data collected along the Los Angeles Regional Seismic Experiment (LARSE) and preliminary model of regional density variations in basement rocks, southern California. [Menlo Park, CA] : U.S. Geological Survey, 1996.

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Solomon, Sean C. Inversion of gravity and bathymetry in oceanic regions for long-wavelength variations in upper mantle temperature and composition : Final report to the National Aeronautics and Space Administration on NASA grant NAGW-3036. [Washington, DC] : The Administration, 1993.

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Soveshchanie, Akademii͡a nauk SSSR Mezhduvedomstvennyĭ geofizicheskiĭ komitet Komissii͡a po izuchenii͡u sily ti͡azhesti. Povtornye gravimetricheskie nabli͡udenii͡a : Sbornik nauchnykh trudov soveshchanii͡a Komissii po izuchenii͡u sily ti͡azhesti (Moskva, mart 1986 g.). Moskva : Akademii͡a nauk SSSR, Mezhduvedomstvennyĭ geofizicheskiĭ kom-t pri Prezidiume AN SSSR, 1988.

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D, Bulanzhe I͡U, Veselov K. E, Faĭtelʹson A. Sh, Kriger E. P et Akademii͡a nauk SSSR. Mezhduvedomstvennyĭ geofizicheskiĭ komitet., dir. Povtornye gravimetricheskie nabli͡udenii͡a : Sbornik nauchnykh trudov. Moskva : Akademii͡a nauk SSSR, Mezhduvedomstvennyĭ geofizicheskiĭ kom-t pri Prezidiume AN SSSR, 1986.

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Vecchiato, Alberto. Variational Approach to Gravity Field Theories. Cham : Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-51211-2.

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Blaha, Stephen. The origin of the standard model : The genesis of four quark and lepton species, parity violation, the electro weak sector, color SU(3), three visible generations of fermions, and one generation of dark matter with dark energy ; Quantum theory of the third kind : a new type of divergence-free quantum field theory supporting a unified standard model of elementary particles and quantum gravity based on a new method in the calculus of variations. Auburn, NH : Pingree-Hill Publishing, 2006.

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Center, Lewis Research, dir. Convective instability of a gravity modulated fluid layer with surface tension variation. [Cleveland, Ohio] : National Aeronautics and Space Administration, Lewis Research Center, 1998.

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Chapitres de livres sur le sujet "Gravity variations"

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Kopaev, A. « Secular Gravity Variations ». Dans Geodesy and Physics of the Earth, 213–16. Berlin, Heidelberg : Springer Berlin Heidelberg, 1993. http://dx.doi.org/10.1007/978-3-642-78149-0_51.

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Wollard, George P. « Regional Variations in Gravity ». Dans The Earth's Crust and Upper Mantle, 320–41. Washington, D. C. : American Geophysical Union, 2013. http://dx.doi.org/10.1029/gm013p0320.

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Araneda, Manuel, et M. Soledad Avendaño. « Gravity Variations in Central Chile ». Dans Recent Geodetic and Gravimetric Research in Latin America, 176–83. Berlin, Heidelberg : Springer Berlin Heidelberg, 1993. http://dx.doi.org/10.1007/978-3-642-88055-1_14.

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Melchior, P., T. M. van Dam, O. Francis et N. d'Oreye. « About Time Variations of Gravity ». Dans Selected Papers From Volume 32 of Vychislitel'naya Seysmologiya, 198–207. Washington, D. C. : American Geophysical Union, 2013. http://dx.doi.org/10.1029/cs007p0198.

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Kuo, John T., et Maurice Ewing. « Spatial Variations of Tidal Gravity ». Dans The Earth Beneath the Continents, 595–610. Washington, D. C. : American Geophysical Union, 2013. http://dx.doi.org/10.1029/gm010p0595.

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Demirel, H., et C. Gerstenecker. « Secular Gravity Variations Along the North Anatolian Fault ». Dans Gravity, Gradiometry and Gravimetry, 163–69. New York, NY : Springer New York, 1990. http://dx.doi.org/10.1007/978-1-4612-3404-3_19.

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Dimitrijevic, Ivan, Branko Dragovich, Zoran Rakic et Jelena Stankovic. « Variations of Infinite Derivative Modified Gravity ». Dans Springer Proceedings in Mathematics & ; Statistics, 91–111. Singapore : Springer Singapore, 2018. http://dx.doi.org/10.1007/978-981-13-2715-5_5.

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Burša, M., Z. Martinec et K. Pěč. « Gravity Field of Phobos and its Long Term Variations ». Dans Gravity, Gradiometry and Gravimetry, 119–25. New York, NY : Springer New York, 1990. http://dx.doi.org/10.1007/978-1-4612-3404-3_14.

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Tiwari, Virendra M., et Jacques Hinderer. « Gravity Field, Time Variations from Surface Measurements ». Dans Encyclopedia of Solid Earth Geophysics, 1–8. Cham : Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-10475-7_236-1.

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Cazenave, A., J. L. Chen et G. Ramillien. « Gravity Field, Temporal Variations from Space Techniques ». Dans Encyclopedia of Solid Earth Geophysics, 1–6. Cham : Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-030-10475-7_96-1.

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Actes de conférences sur le sujet "Gravity variations"

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Bronnikova, K. A., et M. V. Skvortsova. « Variations of fundamental constants and multidimensional gravity ». Dans Twelfth Asia-Pacific International Conference on Gravitation, Astrophysics, and Cosmology. WORLD SCIENTIFIC, 2016. http://dx.doi.org/10.1142/9789814759816_0005.

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Cogbill, Allen H. « Gravity variations observed from a detailed gravity survey at the NTS cloud chamber ». Dans SEG Technical Program Expanded Abstracts 2002. Society of Exploration Geophysicists, 2002. http://dx.doi.org/10.1190/1.1817379.

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Rudenko, K. V., P. S. Solenov et V. N. Rudenko. « Detection of slow gravity field variations with GW-interferometers ». Dans Twelfth Asia-Pacific International Conference on Gravitation, Astrophysics, and Cosmology. WORLD SCIENTIFIC, 2016. http://dx.doi.org/10.1142/9789814759816_0021.

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Blecha, Vratislav. « Corrections for time variations of gravity in microgravity surveys ». Dans SEG Technical Program Expanded Abstracts 2002. Society of Exploration Geophysicists, 2002. http://dx.doi.org/10.1190/1.1817371.

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Preusse, Peter, Manfred Ern, Klaus U. Grossmann et John L. Mergenthaler. « Seasonal variations of gravity wave variance inferred from CLAES ». Dans Remote Sensing, sous la direction de Klaus Schaefer, Adolfo Comeron, Michel R. Carleer et Richard H. Picard. SPIE, 2004. http://dx.doi.org/10.1117/12.514171.

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Karmakar, D., J. Bhattacharjee et T. Sahoo. « Flexural Gravity Wave Scattering Due to Variations in Bottom Topography ». Dans ASME 2009 28th International Conference on Ocean, Offshore and Arctic Engineering. ASMEDC, 2009. http://dx.doi.org/10.1115/omae2009-79191.

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Résumé :
Oblique flexural gravity wave scattering due to abrupt change in bottom topography is investigated under the assumption of linearized theory of water waves. The problem is studied first for single step in case of finite water depth whose solution is obtained based on the expansion formulae for flexural gravity wavemaker problem and corresponding orthogonal mode-coupling relation. The results for the multiple step topography are obtained from the result of single step using the method of wide-spacing approximation. Energy relation for oblique flexural gravity wave scattering due to change in bottom topography is used to check the accuracy of the computation. Using shallow water approximation the wave scattering due to multiple step topography is derived considering the continuity of mass and energy flux. In this case also the result for single step topography is obtained and then using the wide-spacing approximation the result for multiple steps are derived. Numerical results for reflection and transmission coefficients and deflection of ice sheet are obtained to analyze the effect of multiple step topography on the propagation of flexural gravity waves.
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Lehn, Waldemar H., Wayne K. Silvester et David M. Fraser. « Mirages with Atmospheric Gravity Waves ». Dans Light and Color in the Open Air. Washington, D.C. : Optica Publishing Group, 1993. http://dx.doi.org/10.1364/lcoa.1993.thb.3.

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Jing Zhang, Lingyu Yang et Gongzhang Shen. « Modeling and attitude control of aircraft with center of gravity variations ». Dans 2009 IEEE Aerospace conference. IEEE, 2009. http://dx.doi.org/10.1109/aero.2009.4839615.

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Ander, Mark E., et Tom Summers. « LaCoste & ; Romberg gravity meter : Tares, drift, and temporal mass variations ». Dans SEG Technical Program Expanded Abstracts 1997. Society of Exploration Geophysicists, 1997. http://dx.doi.org/10.1190/1.1885943.

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Cherniakov, Sergei M., Valentin C. Roldugin et Alexey V. Roldugin. « Airglow intensity variations affected by acoustic-gravity waves at high latitudes ». Dans XXII International Symposium Atmospheric and Ocean Optics. Atmospheric Physics, sous la direction de Gennadii G. Matvienko et Oleg A. Romanovskii. SPIE, 2016. http://dx.doi.org/10.1117/12.2242778.

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Rapports d'organisations sur le sujet "Gravity variations"

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Harris, R. N., et D. A. Ponce. High-precision gravity network to monitor temporal variations in gravity across Yucca Mountain, Nevada. Office of Scientific and Technical Information (OSTI), décembre 1988. http://dx.doi.org/10.2172/60645.

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Lambert, A., J. Henton, S. Mazzotti, J. Huang, T S James, N. Courtier et G. van der Kamp. Postglacial rebound and total water storage variations in the Nelson River drainage basin : a gravity-GPS study. Natural Resources Canada/ESS/Scientific and Technical Publishing Services, 2013. http://dx.doi.org/10.4095/292189.

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Maceira, Monica, Robert D. van der Hilst et Haijiang Zhang. 3D Variations in Seismic Wavespeed and Mass Density in the Crust and Upper Mantle of SE Asia from Joint Inversion of Seismic and Gravity Data. Office of Scientific and Technical Information (OSTI), juin 2014. http://dx.doi.org/10.2172/1134770.

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Alpay, S., S. Day, R. McNeil, M. McCurdy et P. Gammon. Variations on a theme of gravity coring : K-B, Glew and TechOps corers with core extrusion and high-resolution vertical sectioning of shallow aquatic sediments. Natural Resources Canada/ESS/Scientific and Technical Publishing Services, 2011. http://dx.doi.org/10.4095/288037.

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Alpay, S., S. Day, R. McNeil, M. McCurdy et P. Gammon. Variations on a theme of gravity coring : K-B, Glew and TechOps corers with core extrusion and high-resolution vertical sectioning of shallow aquatic sediments. Natural Resources Canada/ESS/Scientific and Technical Publishing Services, 2011. http://dx.doi.org/10.4095/288046.

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Wiemann, Michael C., et G. Bruce Williamson. Wood Specific Gravity Variation with Height and Its Implications for Biomass Estimation. Madison, WI : U.S. Department of Agriculture, Forest Service, Forest Products Laboratory, 2014. http://dx.doi.org/10.2737/fpl-rp-677.

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Bundy, Mark L. Variation in Gravity Droop Due to Gun Elevation : A Small but Predictable Source of Aiming Inaccuracy. Fort Belvoir, VA : Defense Technical Information Center, février 1994. http://dx.doi.org/10.21236/ada276518.

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