Дисертації з теми "Geophysics Observations"
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Shcherbenko, Gina Nicole. "Post-Seismic Strain and Stress Evolution from Continuous GPS Observations." Thesis, State University of New York at Stony Brook, 2014. http://pqdtopen.proquest.com/#viewpdf?dispub=1567846.
Повний текст джерелаStrain evolution and stress evolution following the 4 April 2010 M7.2 El Mayor-Cucapah earthquake are modeled using an adaptation of the strain transient detection tool developed by Holt and Shcherbenko 2013. The evolution of stress is calculated from postseismic strains, which are modeled from continuous GPS horizontal displacements. Strain fields are modeled in 2 ways; the total strain field based on total observed cGPS displacements, and the residual strain field, which subtracts a reference field from the total model. The residual shows anomalous strains resulting from the postseismic relaxation of the 2010 event. Anomalous and total strains are modeled in 0.1 year epochs for 2.4 years following the event. Both total and anomalous strains are converted into stress changes over time, assuming elastic incompressible behavior. Following the El Mayor event, the GPS constrained strain evolution shows the following: (1) The Southern San Andreas experiences a reduced rate of right-lateral strike slip strain accumulation between 3 July 2010 and 7 August 2012 (Figure 16a-d). (2) The San Jacinto Fault has normal rate of right-lateral strike-slip strain accumulation during this time. (3) Before the Brawley swarm of 26 August 2012, the state of strain evolves to enable unclamping of a left-lateral fault zone in the Brawley Seismic Zone (Figure 16a-d). (4) Large shear strains accumulate on the Laguna Salada Fault (northernmost segment)/southern Elsinore FZ (Figure 16a-d). We converted the strain changes into Coulomb stress changes on existing faults (both right-lateral and left-lateral). Several regions show increased Coulomb stress changes throughout the postseismic process. Furthermore, the Coulomb stress changes on the faults in the region progressively increase toward failure up to the time of the Brawley swarm.
De, Michele Marcello. "Observations seismo-tectoniques par télédétection satellitaire." Phd thesis, Université Pierre et Marie Curie - Paris VI, 2010. http://tel.archives-ouvertes.fr/tel-00656931.
Повний текст джерелаO'Toole, Thomas Bartholomew. "Studies of earthquakes and microearthquakes using near-field seismic and geodetic observations." Thesis, University of Oxford, 2013. http://ora.ox.ac.uk/objects/uuid:9dcaca2e-c141-4e8a-94f6-34a9ff50d061.
Повний текст джерелаMorrow, Eric. "Estimates of Land Ice Changes from Sea Level and Gravity Observations." Thesis, Harvard University, 2014. http://dissertations.umi.com/gsas.harvard:11385.
Повний текст джерелаEarth and Planetary Sciences
Enderlin, Ellyn Mary. "Observations and Modeling of Greenland Outlet Glacier Dynamics." The Ohio State University, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=osu1372609057.
Повний текст джерелаDardel, Cécile. "Entre désertification et reverdissement du Sahel : Diagnostic des observations spatiales et in situ." Phd thesis, Université Paul Sabatier - Toulouse III, 2014. http://tel.archives-ouvertes.fr/tel-00944267.
Повний текст джерелаGonzález-Caneda, María. "Investigation Of Source Parameters Of Earthquakes In Northern Sweden." Thesis, Uppsala universitet, Geofysik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-380133.
Повний текст джерелаCotton, Julien. "Analyse et traitement de données sismiques 4D en continu et en temps réel pour la surveillance du sous-sol." Electronic Thesis or Diss., Paris Sciences et Lettres (ComUE), 2019. http://www.theses.fr/2019PSLEM023.
Повний текст джерела3D seismic reflection is widely used in the oil industry. This standard subsoil auscultation method provides information on geological structures and can be used to build reservoir models. However, the properties derived from3D (and 2D) seismic data are only static: 3D does not allow to evaluate the changes with calendar time. The addition of a temporal dimension to 3D data is obtained by repeating the measurements at several dates separated by several months or even several years. Thus, 4D seismic (time-lapse) makes it possible to measure and to analyze the changes of the subsoil in the long term. Since the 90s, this method is used worldwide at sea and on land. To carry out a much more frequent monitoring (daily), even continuous (a few hours) of the subsoil, CGG developed, in collaboration with Gazde France (now ENGIE) and Institut Français du Pétrole (now IFPEN), a solution based on buried sources and receptors: SeisMovie. SeisMovie was originally designed to monitor and map the gas front in real time during geological disposal operations. It is also used to observe the steam injection required for heavy oil production. In this thesis, we bring contributions to three challenges arising in the processing of seismic data from this system. The first one concerns the attenuation of near-surface variations caused by "ghost" waves that interfere with primary waves. The second one concerns the quantification of subsurface changes in terms of propagation velocity variation and acoustic impedance.The third one concerns real-time: the data processing must be at least as fast as the acquisition cycle (a few hours). Infact, the analysis of the data must enable the reservoir engineers to make quick decisions (stop of the injection, decreaseof the production). In a more general context, there are conceptual similarities between 3D and 4D. In 4D, the repeated acquisitions are compared with each other (or with a reference). In 3D, during acquisition, field geophysicists compare unitary shot points with each other to assess the quality of the data for decision-making (reshooting, skipping orcontinuing). Therefore, some 4D real-time tools developed during this thesis can be applied. A new approach called TeraMig for automated quality control in the field will also be presented
Cordisco, Emmanuel. "Etude de la synergie des observations satellites pour la caractérisation du manteau neigeux." Phd thesis, Université Pierre et Marie Curie - Paris VI, 2005. http://tel.archives-ouvertes.fr/tel-00089376.
Повний текст джерелаCes travaux visent ainsi à étudier le contenu en information sur le manteau neigeux à l'échelle globale des observations satellites réalisées à partir de différents instruments couvrant différents domaines du spectre électromagnétique (visible, infrarouge et micro-ondes). Des paramètres autres que la neige interférant dans la problématique, il est nécessaire de les déterminer afin d'encadrer leurs influences. Ensuite, on cherchera comment limiter la pollution qu'engendre ces paramètres sur l'information accessible du manteau neigeux, on aura alors recours à ce que l'on appelera des statistiques locales.
Hélas ces statistiques locales ne sont pas disponibles sur l'ensemble du globe. Il est donc inévitable d'utiliser la modélisation pour permettre l'interpolation. Toutefois, une méthode originale d'ajustement de modèle par analyse en composantes principales sera présentée. Au final, la synergie entre les observations satellites, la modélisation et les mesures in situ devra être utilisée pour extraire de façon optimale l'information contenu dans les données et permettre l'inversion de l'épaisseur de neige à grande échelle.
D'autre part, il sera intéressant de caractériser les différents types de neiges existants selon une classification non-supervisée des observations satellites afin d'extraire les similitudes et les spécificités de chacun de ces types.
Eymin, Céline. "Etude des mouvements à la surface du noyau terrestre : du 17ème au 21ème siècle." Phd thesis, Université Pierre et Marie Curie - Paris VI, 2004. http://tel.archives-ouvertes.fr/tel-00007173.
Повний текст джерелаhistoriques et un modèle détaillé des mouvements actuels sont obtenus. L'estimation des marges d'erreurs associées permet d'identifier les structures fiables. Nos reconstructions sont en accord avec différents phénomènes mis en évidence par des modélisations 3D du noyau. Nous montrons aussi que les jerks géomagnétiques ont une signature dynamique très nette. Enfin, nous posons les bases d'une méthode d'assimilation variationnelle de données adaptée à l'étude du noyau.
Horgan, Huw J. Anandakrishnan Sridhar. "Geophysical observations of polar ice sheets and ice shelves." [University Park, Pa.] : Pennsylvania State University, 2009. http://etda.libraries.psu.edu/theses/approved/WorldWideIndex/ETD-4587/index.html.
Повний текст джерелаIto, Garrett Tetsuo. "Mantle plume-midocean ridge interaction : geophysical observations and mantle dynamics." Thesis, Massachusetts Institute of Technology, 1996. http://hdl.handle.net/1721.1/59638.
Повний текст джерелаFerenc, Marcell. "GPS observation of geophysical deformations induced by non tidal loading." Thesis, Paris, CNAM, 2014. http://www.theses.fr/2014CNAM0977/document.
Повний текст джерелаThe temporal and spatial redistribution of the environmental masses deform the surface of the Earth. These deformations are observable by space geodetic techniques such as GNSS. Since highly accurate IGS satellite and clock data are available and sophisticated algorithms have been developped, the integer fixed ambiguity Precise Point Positioning (iPPP) method opened a new era for the Global Navigation Satellite System (GNSS) analysis and its application in geophysical studies. This work is among the first studies to investigate the different loading effects using iPPP time series, particularly using the GINS-PC software and the new, reprocessed REPRO2 orbit and clock products of GRGS (GR2). We aim to exploit the sub-daily iPPP time series to study various Earth deformation effects at different time scales, from sub-daily to seasonal and annual periods. Our goal is to contribute to the validation of geophysical models, to the observation of the various non-tidal phenomena, as well as the presentation of the performance of the iPPP mode and the GINS-PC package that is a powerful tool for geodynamical applications, and to investigate the influence of the loading effects on geodetic time series interpretation. After an overview of the main deformations of the Earth's surface, we present the geodetic techniques that already demonstrated their potential in deformation analysis, in particular in loading deformation studies. We then review the GNSS technique and the iPPP processing mode as it was our choice for the data analysis. We then demonstrate two regional studies. The first one investigates the influence of the loading effects on GNSS campaign to determine tectonic velocities in the Pyrenees mountain chain. The second case study attempts to track the spatial and temporal evolution of an extreme storm event, the Xynthia windstorm that occured in France, in 2010. This study also tries to identify the ocean's response to the fast moving low pressure system using sub-daily iPPP time series. Finally we go towards a global study which gives base for future research
Sansom, Victoria. "Crustal structure of the NE Seychelles rifted continental margin from geophysical observations." Thesis, Imperial College London, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.497263.
Повний текст джерелаRussell, Frances Marion. "Semi-permanent zones of radar radial shear within the planetary boundary layer : observations and effects on high intensity precipitation in the wider Auckland region, New Zealand : a thesis submitted to the Victoria University of Wellington in partial fulfilment of the requirements for the degree of Master of Science in Geophysics /." ResearchArchive@Victoria e-Thesis, 2009. http://hdl.handle.net/10063/1215.
Повний текст джерелаWang, Caixia. "Geophysical observations of nonlinear internal solitary-like waves in the Strait of Georgia." Thesis, University of British Columbia, 2009. http://hdl.handle.net/2429/17468.
Повний текст джерелаGresse, Marceau. "Imagerie géophysique (électrique et sismique) haute résolution et modélisation du système hydrothermal superficiel de la Solfatare de Pouzzoles, Italie du Sud. Application à l’étude des processus hydrothermaux." Thesis, Université Grenoble Alpes (ComUE), 2017. http://www.theses.fr/2017GREAU035/document.
Повний текст джерелаThe Campi Flegrei caldera is located in the metropolitan area of Naples (Italy), and it is one of the largest volcanic systems on Earth. Since 1950, this volcanic complex shows significant unrest, which accelerated over the last decade with a rise in the seismic activity, ground deformation, and the extent of the degassing area. Recent studies indicate that the volcanic system is potentially moving toward a critical state, although their authors remain unable to point out when and where a possible eruption could take place. The difficulty of predicting the real volcanic state is here mainly related to the hydrothermal system. Indeed, at the Campi Flegrei, it is difficult to separate the magmatic input signal from the hydrothermal response. Hence, the aim of this thesis is to improve our knowledge on the shallow hydrothermal system of the Solfatara volcano, where most of the renewal activity takes place. A multidisciplinary approach has been performed in two steps: first a geophysical imagery of the volcano and second the modeling of its hydrothermal system.The 3-D electrical resistivity tomography of the crater allows to recognize the main geological units, and their connection with hydrothermal fluid flow features. The interpretation of the resistivity model has been realized thanks to numerous soil complementary measurements: CO2 flux, temperature, self-potential, Cation Exchange Capacity and pH. We identify two liquid-dominated plumes: the Fangaia mud pool and the Pisciarelli fumarole. In the Fangaia area, the comparison between electrical resistivity and velocity models reveals strong gradients related to a sharp transition at the border between the hydrothermal plume and the high diffuse degassing region. Combining electrical resistivity model with hydrothermal tremor sources localization reveal the anatomy of the main fumarolic area. Two separated conduits, gas-saturated, feed the two fumaroles Bocca Grande and Bocca Nuova. These conduits originate from the same gas reservoir located 60 m below the surface. The intense degassing activity, produced in the vicinity of fumaroles, creates large amounts of vapor condensation. The resistivity model reveals this condensate circulation, within a fractured area.All these results are incorporated into a multiphase flow model of the main fumarolic area. The simulation accurately reproduces the fumaroles observables: temperature, flux and CO2/H2O ratio. The model validates the geophysical imagery and confirms the interaction between Bocca Nuova fumarolic conduit and the condensate flow. Hence, this simulation explains for the first time the distinct geochemical signature of the two fumaroles due to a shallow water-interaction. The multidisciplinary approach performed in this thesis constitutes a new step toward a better understanding of hydrothermal interactions. Those phenomena have to be taken into account in order to perform dynamic modelling, and thus apprehend the real state of the volcanic system
Rickert, Eric Andrew. "Hydrologica and Borehole Geophysical Investigation of Bedrock Observation Wells at the University of Maine." Fogler Library, University of Maine, 2005. http://www.library.umaine.edu/theses/pdf/RickertEA2005.pdf.
Повний текст джерелаGilbert, Lisa A. "Shallow crustal structure of Axial Seamount : geophysical inversion of sea surface and near seafloor gravity observations /." Thesis, Connect to this title online; UW restricted, 2004. http://hdl.handle.net/1773/11025.
Повний текст джерелаWalters, Richard John. "Geodetic observation and modelling of continental deformation in Iran and Turkey." Thesis, University of Oxford, 2012. http://ora.ox.ac.uk/objects/uuid:39c0e88a-4f45-483a-b8e1-6a7dc3e9d41b.
Повний текст джерелаPeruzzo, Luca. "Geoelectrical approaches for characterizing soil geochemical processes and soil-root interactions." Thesis, Bordeaux 3, 2019. http://www.theses.fr/2019BOR30015.
Повний текст джерелаIn this thesis I investigate some of the possibilities offered by the use of geoelectrical methods for characterizing soil geochemical processes and root-soil interactions. The motivation for this thesis arises from the pivotal role of soil quality and root-soil interactions in manifold environmental issues. In addition, there is growing evidence of the importance of mutual interactions between roots and soil, for this reason this thesis explores the use of geoelectrical methods for more comprehensive approaches. Both soil physicochemical processes and root-soil interactions involve, among others, the movement of water and solutes, altercations of the soil structure, and biological feedbacks. Geoelectrical methods are potentially sensitivity to these hydrogeological and biogeochemical modifications. The Spectral Induced Polarization (SIP) method was combined with geochemical analyses and modeling in order to investigate its sensitivity to pore fluid composition, pH, and ionic strength. In particular, the SIP signature of Na+/Cu2+ substitution was investigated because of their worldwide relevance for soil quality. The SIP investigation focused on saturated silica, and explored concentrations of Na+ and Cu2+ that are typical to agricultural soils exposed to the use of Cu pesticides. The results showed how pH and ionic strength were the main variables controlling the SIP signals, while negligible effects were related to the Cu/Na substitution. The concurrent use of chemical and geophysical laboratory experiments allowed a better characterization of the investigated complexation processes and significantly supported the interpretation of the SIP signals. The Electrical Resistivity Tomography and the Mise-A-La-Masse methods were combined to develop a novel approach for imaging the electric current pathways in the root-soil system. Since the current conduction in soil and roots is mostly electrolytic, the proposed approach relates to the movement of water and solutes within the root-soil system. The potential of the method for field investigations was explored with a set of experiments on a grapevine. In light of the promising results, the method was further developed and applied to rhizotron laboratory experiments on cotton and maize plants. The method proved to be sensitive to inter-species physiological differences and possibly to the plant response to environmental stressors. New experiments with physiological analyses of root tissues are needed to elucidate these aspects. Emerging technologies are strongly supporting to the diffusion of imaging and monitoring geoelectrical applications at the field-scale. In this promising context, the results of this thesis contribute to the development of geoelectrical approaches for studying soil and its mutual interactions with plant roots over relevant spatiotemporal scales
Lawrence, Heather. "MODÉLISATION DE L'EFFET DE LA RUGOSITÉ DE SURFACE ET DE LA LITIÈRE DES COUVERTS NATURELS SUR LES OBSERVATIONS MICRO-ONDES PASSIVES - APPLICATION AU SUIVI GLOBAL DE L'HUMIDITÉ DU SOL PAR LA MISSION SMOS." Phd thesis, Université Sciences et Technologies - Bordeaux I, 2010. http://tel.archives-ouvertes.fr/tel-01024075.
Повний текст джерелаUtom, Ahamefula Udume [Verfasser], and Peter [Akademischer Betreuer] Grathwohl. "Observation-Based Conceptual Site Modeling Framework Combining Surface Geophysical, Direct Push-Based, Hydrogeochemical and Stable Isotope Methods / Ahamefula Udume Utom ; Betreuer: Peter Grathwohl." Tübingen : Universitätsbibliothek Tübingen, 2019. http://d-nb.info/1187724505/34.
Повний текст джерелаTravelletti, Julien. "Imagerie multi-paramètres et multi-résolutions pour l'observation et la caractérisation des mécanismes de glissements-coulées." Phd thesis, Université de Caen, 2011. http://tel.archives-ouvertes.fr/tel-00806806.
Повний текст джерелаLévy, Léa. "Propriétés électriques des roches volcaniques altérées : observations et interprétations basées sur des mesures en laboratoire, terrain et forage au volcan Krafla, Islande." Thesis, Paris Sciences et Lettres (ComUE), 2019. http://www.theses.fr/2019PSLEE002/document.
Повний текст джерелаElectromagnetic soundings are widely used to image the underground structure of volcanoes and look for hightemperature geothermal resources. The electrical resistivity of volcanoes is affected by several characteristics of rocks: volume and salinity of pore fluid, abundance of conductive minerals, rock temperature and presence of magma. This thesis aims at improving the interpretation of electrical resistivity structures around active volcanoes, in order to develop innovative tools for the assessment of geothermal resources. I focus on conductive minerals, which can either be solid ionic conductors (clay minerals, in particular smectite) or electronic semi-conductors (pyrite and iron-oxides), but I also investigate the effects of porosity, salinity, temperature and presence of magma. I use Krafla volcano as a laboratory area, where extensive literature, borehole data, core samples, surface soundings and infrastructures are available. Smectite and pyrite are formed upon hydrothermal alteration of volcanic rocks and thus witness hydrothermal convection. On the other hand, iron-oxides are mostly formed during the primary crystallization of magma and dissolved by hydrothermal fluids. The contribution of smectite to the electrical conductivity of volcanic rocks saturated with pore water at different salinity is first investigated in the laboratory (room temperature) by electrical impedance spectroscopy “complex resistivity”. Non-linear variations of the conductivity at 1 kHz with salinity are observed and discussed. Interfoliar conduction is suggested as an important mechanism by which smectite conducts electrical current. The influence of pyrite and iron-oxides on induced polarization effects is then analyzed, using the frequency-dependent phase-angle of the impedance. A maximum phase-angle higher than 20 mrad is attributed to pyrite if the rock is conductive and to ironoxides if the rock is resistive. The maximum phase-angle increases by about 22 mrad for each additional per cent of pyrite or iron-oxide. These laboratory frequency-domain findings are partly upscaled to interpret field time-domain complex resistivity tomography at Krafla: smectite, pyrite and iron-oxides can be identified down to 200 m. The in-situ temperature, higher than in laboratory conditions, appears to significantly increase the conductivity associated to smectite. In general, time-domain complex resistivity measurements are recommended as a complementary method to electromagnetic soundings for geothermal exploration
Багрій, С. М. "Геофізичний моніторинг геологічного середовища в межах родовищ калійної солі (на прикладі Калуш - Голинського родовища)". Thesis, Івано-Франківський національний технічний університет нафти і газу, 2016. http://elar.nung.edu.ua/handle/123456789/31.
Повний текст джерелаThe thesis is devoted to ecological and geological problems that have arisen in the area of waste mine mines of Kalush-Holyn potassium salt deposit. The aim of the paper is using geophysical methods to detect failure-subsidence processes on mine fields and contamination of the aquifer with the waste materials from mining enterprises. The monitoring of Kalush-Holyn potassium salt deposit mine fields were conducted using geophysical methods. The author shows that NPEMFE method is the most convenient to implement such researches. For the first time the classification characteristics of NPEMFE anomalies were formed and agreed with the causes and characteristics of deformation processes. The author formed the criteria for qualitative interpretation for specific geological situations and demonstrated effectiveness of the method for the prediction of subsidence at the stage of rapid information. Author offers the method of calculating the quantitative characteristics of surface subsidence based on analysis of decompacted rocks recorded by gravimetry in monitoring mode. Options for calculating for both discrete and gradient environments are represented. The results are necessary with regard to their informativity for further substantiation of managerial decisions on further exploitation of research areas. Integrated interpretive model of VES and SFF methods was substantiated in this paper. The author has built general electric section for the separate mine fields of Kalush- Holyn deposit taking into account the development of karst processes. This enabled the correction of geological sections in the specification of the lithological composition of rocks of individual layers that allowed the opportunity to outline the area of distribution of fluid clay and establish the degree of erosion of salt mirror regardless of the filling chambers, namely, to get independent information about subsidence and landslides. The paper presents a comprehensive approach of geophysical methods for detailed mapping of the surface subsidence zones, failure-subsidence processes and contaminated zones of the aquifer. Spatial models and criterion failure maps of failure-subsidence danger were built for the mine fields "Kalush” and "Novo Holyn", contaminated zones of the aquifer were delineated and defined with the determination of velocity toward the river Limnytsya.
Chawah, Patrick. "DÉVELOPPEMENT D'UN CAPTEUR DE DÉPLACEMENT À FIBRE OPTIQUE APPLIQUÉ À L'INCLINOMÉTRIE ET À LA SISMOLOGIE." Phd thesis, Université Montpellier II - Sciences et Techniques du Languedoc, 2012. http://tel.archives-ouvertes.fr/tel-00779335.
Повний текст джерелаEissa, Leila. "Utilisation de méthodes de l'astrogéodésie et de la géodésie spatiale pour des études de déformations de l’écorce terrestre : représentations de déformations et de leur degré de signification par des tenseurs régulièrement répartis." Thesis, Paris Est, 2011. http://www.theses.fr/2011PEST1018/document.
Повний текст джерелаSpace geodesy tools are now strongly involved in geophysical studies. The horizontal deformation field for a region of interest is provided by two main methods : a velocity field and a strain tensor field. A strain tensors field solution has the advantage of being independent of the reference frame in which the velocities are expressed. Nevertheless, the current methods of calculation of a strain tensors field depend on the positioning of geodetic points. Furthermore, the current mapping method of tensors by their mains axis is not easy to read and to interpret, needing some training. This thesis is devoted to the problem of calculating a continuous field of regularly spaced strain tensors, and providing an intuitive mapping method of these tensors with a simultaneous representation of their significance level on the same map. The estimation of uncertainties related to the deformation field is made in two steps : firstly, a Monte Carlo method is applied for the calculation of uncertainties related to the measurements, its results allow to define the significance level of tensors by normalizing tensor's values with respect to their related uncertainties, then, the constraints coming from the distribution of the network of measurement points are calculated and combined with the first source of error. The new approach of mapping tensors was analyzed through an opinion survey by providing several possibilities of representation. The results of this opinion survey allowed us to validate this new mapping method by geophysicists for representing a deformation field, because it allows highlighting some aspects not well illustrated by the classical mapping method of tensors, and therefore choosing the graphical elements of the map which provide the best intuitive method of mapping a strain tensors field
Budi, Wibowo Sandy. "Approches multiscalaires de l'érosion du volcan Merapi, Indonésie : contribution à la compréhension du déclenchement et de la dynamique des lahars." Thesis, Paris 1, 2016. http://www.theses.fr/2016PA01H044/document.
Повний текст джерелаThe erosion of volcanic edifices is a series of geomorphological processes that occurs during, before or without eruption. This process also involves the term "lahar" which is characterized by dense mixtures of volcanic materials and water, rapidly flowing from a volcano with important spatio-temporal rheological changes. The erosion of volcanic edifices is still poorly understood, particularly because data collection in the field is difficult. However, lahars have caused at least 44,250 deaths from 1600 to 2010 of which 52%due to a single event in 1985 (Nevado del Ruiz, Colombia).This study proposes a multi-scalar approach to better understand the nature of the erosion of volcanic edifices, especially on lahar initiation process and dynamics. The eruption of the Merapi volcano(Indonesia) in 2010 was an opportunity to produce new data. The first part of this thesis focused on the lahar initiation process, was based on field data and laboratory experiments. The field work was intended to compare a volcanically disturbed watershed by the eruption of 2010 and an undisturbed watershed, by conducting in-situ observations and field instrumentation. In the laboratory, an experimental approach was performed using 8 different scenarios on a flume. The second part of the thesis related to the dynamics of two lahars in motion was conducted using coupling between video footage and seismic signal. Lahar deposits were also analyzed based on the chronology of the flows. Three years after the eruption of Merapi in 2010, the frequency of lahar occurrence decreased. However, juvenile ash fall deposits (volcanic ash) from another eruption of a nearby volcano (Kelud in East Java) in February 2014 resulted a significant increase of lahars occurrence. Lahars triggering process was also favored by a landslides occurring in the night of 6 to 7 December 2012, of which the deposit was connected to the thalweg. The dynamics of the two lahars were observed and filmed on 28 February and18 March 2014. Those lahars were divided into four phases: (1) hyperconcentrated flow, (2) the peak of debris flow, (3) lahar body, and (4) lahar tail. Video analysis and in-situ observation on active lahars allowed us to create detailed hydrographs indicating flow depth, velocity, discharge and the number of floated boulders. Lahar dynamics on different topography of the channel caused a very different seismic frequency. The formation of lahar deposits was correlated with the flow dynamics and required an in-situ observation for the validation of the interpretation
Erosi kerucut vulkanik merupakan hasil dari serangkaian proses geomorfologi yang terjadi baik selama,sebelum atau tanpa erupsi. Proses ini juga melibatkan "lahar" yang didefinisikan sebagai aliran cepat daridaerah puncak gunung menuju hilir dengan membawa material vulkanik yang bercampur dengan airdimana dinamika alirannya terus berubah secara spasial dan temporal. Erosi struktur vulkanik masihsedikit ditelaah, terutama karena sulitnya pengumpulan data di lapangan. Padahal, lahar telahmenyebabkan setidaknya 44.250 kematian dari tahun 1600 sampai 2010, dimana 52% -nya terkait denganbencana pada tahun 1985 di gunung Nevado del Ruiz (Kolombia).Penelitian ini mengusulkan pendekatan multi-skalar untuk lebih memahami karakteristik erosi kerucutvulkanik terutama yang terkait dengan pemicu dan dinamika aliran lahar. Letusan Gunung Merapi(Indonesia) pada tahun 2010 memberikan kesempatan untuk menghasilkan data lapangan baru. Bagianpertama dari disertasi ini, mengenai pemicu lahar, dilakukan berdasarkan data lapangan dan experimenlaboratorium. Kegiatan lapangan dimaksudkan untuk membandingkan DAS yang terdampak oleh letusan2010 dan DAS alami, melalui pengamatan in-situ dan instrumentasi lapangan. Di laboratorium,pendekatan eksperimental dilakukan dengan menggunakan 8 skenario yang berbeda pada flume. Bagiankedua dari disertasi ini berkaitan dengan dinamika aliran lahar aktif yang dipelajari dari perpaduanrekaman video dan sinyal seismik. Proses sedimentasi juga dianalisis dengan dipertimbangkan kronologialiran lahar.Tiga tahun setelah letusan Merapi pada tahun 2010, frekuensi kejadian lahar berkurang. Namun,sedimentasi abu vulkanik yang berasal dari gunung api lain (Kelud di Jawa Timur) telah mengakibatkanpeningkatan jumlah lahar yang signifikan sejak Februari 2014. Pembentukan lahar juga dipicu oleh tanahlongsor yang terjadi pada pada malam 6 menuju 7 Desember 2012 dimana materialnya terhubunglangsung ke thalweg. Dinamika dua aliran lahar diamati dan difilmkan pada tanggal 28 Februari dan 18Maret 2014. Lahar tersebut dibagi menjadi empat fase: (1) aliran hyperconcentrated, (2) puncak alirandebris, (3) tubuh lahar, (4) ekor lahar. Analisis video dan pengamatan in-situ pada lahar aktif sangatmembantu pembuatan hidrograf secara rinci terkait dengan kedalaman aliran, kecepatan, debit dan jumlahbatu yang terapung. Dinamika lahar pada topografi sungai yang berbeda menimbulkan frekuensi seismikyang sangat berbeda. Proses sedimentasi lahar sangat berkaitan dengan dinamika aliran lahar dandiperlukan pengamatan in-situ untuk memvalidasi interpretasi yang dibuat
La erosión de los edificios volcánicos es el resultado de una serie de procesos geomorfológicos que ocurre durante, antes o sin erupción. Este proceso también involucra el término "lahar", un flujo rápido de la cumbre de volcán hacia el rio que contiene una mezcla de materiales volcánicos y agua con cambio espacial y temporal. La erosión de los edificios volcánicos aún es poco estudiado debido a las dificultades para la obtención de los datos en el campo y además es peligroso. Mientras, los lahares han causado 44 250 muertos desde 1600 a 2010, en el cual de 52% ha sido causado por un evento único en 1985 (Nevado del Ruiz, Colombia). Esta investigación propone un acercamiento multiescalar para entender mejor las características de erosión de los edificios volcánicos, en particular el proceso de descenso y la dinámica de lahares. La erupción del volcán Merapi (Indonesia) en 2010 fue una oportunidad para generar nuevos datos. La primera parte de esta tesis enfocada al proceso de iniciación de descenso de lahares, que fue basada en la obtención de los datos de campo y experimentos en el laboratorio. El trabajo de campo fue realizado con el objetivo de comparar una cuenca hidrográfica afectada por la erupción de 2010 y una otra cuenca natural, a través de la observación in-situ y la instrumentación geofísica en el campo. En el laboratorio, el trabajo fue realizado con 8 escenarios diferentes usando un canal artificial. La segunda parte de esta tesis fue relacionada a la dinámica de movimiento de lahares que se realizó a través del acoplamiento de vídeos y señales sísmicas. Se analizó también el proceso de sedimentación basado en la cronología de los flujos de lahares. Tres años después de la erupción del Merapi en 2010, la frecuencia de ocurrencia de lahares se disminuye. Sin embargo, la sedimentación de ceniza volcánica de otra erupción de un volcán cercano (Kelud en Java Oriental) causó un aumento significativo de la ocurrencia de lahares desde febrero de 2014. La formación de lahares también se provocó por deslizamiento de tierra que se ocurrió en la noche de 6 a 7 de diciembre de 2012, en la que los materiales se juntaron directamente a la vaguada. La dinámica de dos flujos de lahares fue observada y grabada en video el 28 de febrero y 18 de marzo 2014. Estos dos lahares se dividieron en cuatro fases: (1) flujo hiperconcentrado, (2) el pico de flujo de escombros, (3) cuerpo de lahar, (4) cola de lahar. El análisis de video y la observación in-situ de lahares activos nos han ayudado a crear los hidrogramas en detalle que muestran la profundidad del flujo, la velocidad, la descarga y el número de rocas flotadas. La dinámica de lahares en diferentes topografías del canal causó una frecuencia sísmica muy diferente. El proceso de sedimentación de lahares se correlacionó con la dinámica de flujo y se requiere una observación in-situ para validar la interpretación
Mutnuri, Kartik. "Diffuse oceanic plate boundaries: Kinematic observations and rheological constraints." Thesis, 2006. http://hdl.handle.net/1911/17900.
Повний текст джерелаFoster, Anna. "Surface-wave propagation and phase-velocity structure from observations on the USArray Transportable Array." Thesis, 2014. https://doi.org/10.7916/D8959FQR.
Повний текст джерела(8817314), Grant Bonnette. "Characterizing Deformation Along an Early-Stage Rift: GPS Observations from the Northern Lake Malawi (Nyasa) Rift." Thesis, 2020.
Знайти повний текст джерелаMoulik, Pritwiraj. "Earth's Elastic and Density Structure from Diverse Seismological Observations." Thesis, 2016. https://doi.org/10.7916/D85X28V5.
Повний текст джерела"Using Micro-Scale Observations to Understand Large-Scale Geophysical Phenomena: Examples from Seismology and Mineral Physics." Doctoral diss., 2015. http://hdl.handle.net/2286/R.I.36416.
Повний текст джерелаDissertation/Thesis
Great Basin Seismicity from 2004 to 2013 (event data)
Great Basin Seismicity from 2004 to 2013 (Google Earth)
Doctoral Dissertation Geological Sciences 2015
Howe, Michael Joseph. "Improving Estimates of Seismic Source Parameters Using Surface-Wave Observations: Applications to Earthquakes and Underground Nuclear Explosions." Thesis, 2019. https://doi.org/10.7916/d8-28rw-kz47.
Повний текст джерелаHatam, Yaghoub. "Etablissement des nouveaux réseaux multi-observations géodésiques et gravimétriques et détermination du géoïde en Iran." Phd thesis, 2010. http://tel.archives-ouvertes.fr/tel-00627614.
Повний текст джерелаBlatter, Daniel. "Constraining fluid properties in the mantle and crust using Bayesian inversion of electromagnetic data." Thesis, 2020. https://doi.org/10.7916/d8-b6nw-b545.
Повний текст джерелаDella, Ceca Lara Sofía. "Análisis espacio-temporal de la distribución de aerosoles atmosféricos en la ciudad de Córdoba (Argentina) y desarrollo de un modelo predictivo de los niveles de material particulado." Master's thesis, 2018. http://hdl.handle.net/11086/6009.
Повний текст джерелаMaestría conjunta con el Instituto de Altos Estudios Espaciales "Mario Gulich"-CONAE.
En esta tesis se estudia la variabilidad espacio-temporal de los aerosoles atmosféricos en la ciudad de Córdoba (Argentina) y sus alrededores para un período mayor a 10 años (2003-2013), mediante el uso del producto satelital espesor óptico de aerosoles (o AOD por Aerosol Optical Depth, en inglés) de frecuencia diaria obtenido con el algoritmo denominado implementación de corrección atmosférica multi-ángulo (MAIAC) que ha sido recientemente desarrollado para los datos obtenidos con el sensor MODIS (a bordo de los satélites Terra y Aqua/NASA). Hasta el momento; los productos de AOD disponibles presentaban resoluciones espaciales mayores a 3 km, adecuados para estudios a escala regional. Sin embargo no proveían suficiente detalle para el estudio de áreas urbanas o para estudios epidemiológicos. Con este objetivo se desarrolló este nuevo algoritmo, aún en fase de prueba, que mejora sensiblemente la resolución espacial a 1 km, con lo cual resulta más apropiado para el estudio de los aerosoles atmosféricos a escala urbana. En este trabajo, en una primera instancia se evaluó la performance del producto AOD-MAIAC mediante la comparación con valores de AOD obtenidos desde superficie en la estación Córdoba-CETT de la red AERONET. Se analizó la concentración y variación anual de los aerosoles, así como su variación mensual y estacional. Por último, se estudió la relación entre los valores satelitales de AOD-MAIAC y valores de material particulado (PM) obtenidos desde la superficie por una estación de monitoreo de la Municipalidad de Córdoba que funcionó en el centro de la ciudad durante enero-agosto de 2009. En general, el algoritmo MAIAC presentó una buena performance en el área de estudio. Los resultados reflejaron que, a pesar de que los valores de AOD son bajos respecto a otros sitios del mundo muy contaminados, existe una tendencia de incremento de AOD a lo largo del tiempo particularmente en algunas zonas de la ciudad (como por ejemplo el acceso a Sierras Chicas y la zona norte de la ciudad) que podría estar vinculado al aumento de la densidad poblacional en esa área y el consecuente incremento del tránsito vehicular. Además se observó un patrón de incremento o disminución en los niveles de AOD en determinados momentos del año. Durante los meses de verano (diciembre-febrero) se observaron valores relativamente altos concentrados en la ciudad de Córdoba, en las principales vías de acceso hacia las zonas turísticas así como en el anillo de circunvalación de la ciudad Hacia el otoño los valores de AOD comienzan a disminuir hasta alcanzar los valores más bajos durante los meses de invierno. A partir de agosto se observa un gran incremento del AOD que tiene su pico máximo durante septiembre y se mantiene elevado durante el resto de la primavera. Este incremento de AOD coincide con 2la estación de quema de biomasa en la provincia de Córdoba, el norte argentino y otras regiones de Sudamérica (Bolivia, Paraguay, Amazonia y Cerrado en Brasil) y evidencia la importancia del transporte atmosférico a escala regional pero también continental de material particulado que es liberado a la atmósfera durante los incendios. Los modelos de regresión lineal desarrollados en este estudio para evaluar la relación entre AOD-PM y variables meteorológicas no son suficientes para explicar la variabilidad de los datos de PM medidos en superficie a partir de los valores satelitales de AOD y las variables meteorológicas. Sin embargo, los resultados presentados constituyen un primer estudio exploratorio para la ciudad de Córdoba. Dada la falta de estaciones superficiales de monitoreo de material particulado en Argentina, y en particular en la ciudad de Córdoba, este estudio intentó ser una línea de base para el estudio de la dinámica de los aerosoles atmosféricos a escala urbana a partir de información satelital y constituye una primera aproximación a la problemática.
Fil: Della Ceca, Lara Sofía. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía, Física y Computación; Argentina.
Fil: Della Ceca, Lara Sofía. Universidad Nacional de Córdoba. Instituto de Altos Estudios Espaciales Mario Gulich; Argentina.
Legaz, Aurélie. "Imagerie et identification des signaux géophysiques distinctifs induits en surface par l'activité hydrothermale." Phd thesis, 2008. http://tel.archives-ouvertes.fr/tel-00813307.
Повний текст джерелаHowell, James F. 1965. "Sudden changes in local mean values demarcate geophysical regimes." Thesis, 1995. http://hdl.handle.net/1957/29063.
Повний текст джерелаGraduation date: 1996
Gowan, Evan James. "Glacio-isostatic adjustment modelling of improved relative sea-level observations in southwestern British Columbia, Canada." Thesis, 2007. http://hdl.handle.net/1828/263.
Повний текст джерелаWang, Hailong. "Modeling and observational studies of shallow cumulus convection over the Indian Ocean : aerosol and meteorological effects on diurnal cycles /." 2007. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3290419.
Повний текст джерелаSource: Dissertation Abstracts International, Volume: 68-11, Section: B, page: 7387. Adviser: Greg M. McFarquhar. Includes bibliographical references (leaves 178-192) Available on microfilm from Pro Quest Information and Learning.
Hanekop, Ole. "Large scale resistivity surveys combining magnetic and magnetotelluric observations." Doctoral thesis, 2006. http://hdl.handle.net/11858/00-1735-0000-0006-B43F-B.
Повний текст джерелаLachet, Corinne. "Observation des séismes en milieux urbains : méthodes simples d'étude des effets de site et de simulation des mouvements forts." Phd thesis, 1996. http://tel.archives-ouvertes.fr/tel-00744999.
Повний текст джерелаWartenberg, Wolfram [Verfasser]. "The concealed Tamworth Belt (New England Orogen) - stratigraphic and geophysical observations depicting a thrust-related geometry in southern Queensland, Australia / vorgelegt von Wolfram Wartenberg." 2005. http://d-nb.info/975270400/34.
Повний текст джерелаOmpré, Oscar Franco. "Estudio del efecto de Sunglint en las señales captadas por sensores satelitales en el rango espectral de visible a infrarrojo cercano mediante simulación numérico." Bachelor's thesis, 2018. http://hdl.handle.net/11086/6547.
Повний текст джерелаEn la actualidad es de suma importancia la obtención de parámetros de ocean color, es decir, datos que nos aportes información sobre el contenido de los océanos y mares como por ejemplo los niveles de fitoplancton que componen un aspecto fundamental en las cadenas de producción pesquera y la forma en la cual evolucionan los ecosistemas dentro de los océanos. Mediante el uso de satélites con sensores a bordo capaces de obtener estas variables es posible llevar a cabo un monitoreo constante, pero en determinadas situaciones es de extrema dificultad la obtención de las variables de ocean color. En este trabajo se estudia y caracteriza el fenómeno de sunglint , es decir la reflexión especular del sol en la superficie del agua de mar, para conocer de que forma se comporta y cuales son los parámetros mas sensibles utilizando un modelo de trasferencia radiativa. La radiación que llega al satélite debido a este efecto termina por cubrir completamente las radiancias que tienen directa relación con los componentes del agua, como el la Water Leaving Radiance(WLR). Si se pudiera caracterizar de forma univoca esta radiación y conocer los parámetros por los cuales esta es producida se podría diseñar una corrección que sumada a la corrección atmosférica permita obtener las variables de ocean color deseadas.
At present it is very important to obtain parameters of textit ocean color, that is, data that provide us with information about the content of the oceans and seas, such as the phytoplankton levels that make up a fundamental aspect in the chains of fishing production and the way in which the ecosystems evolve within the oceans. By using satellites with on-board sensors capable of obtaining these variables it is possible to carry out constant monitoring, but in certain situations it is extremely difficult to obtain the ocean color variables. In this work we study and characterize the phenomenon of textit sunglint, that is to say, the specular reflection of the sun on the surface of seawater, in order to know which way it behaves and what are the more sensitive parameters using a radiative transfer model. The radiation that reaches the satellite due to this effect ends up completely covering the radiances that have a direct relation with the water components, such as the Water Leaving Radiance (WLR). If this radiation could be characterized univocally and know the parameters by which it is produced, a correction could be designed that, added to the atmospheric correction, allows to obtain the desired ocean color variables.
Castillo, Rosales Yvelice Soraya. "Global and mid-latitude impact of ten years of solar activity using observational data of the geophysical and astronomical observatory of the University of Coimbra." Doctoral thesis, 2018. http://hdl.handle.net/10316/79592.
Повний текст джерелаThe focus of this thesis is to identify the role and dynamics of different current systems for storm-time activity at mid-latitude ground level and their relation with other solar, interplanetary and geomagnetic parameters, in the 2007-2016 time interval. For this purpose, I compared the synthetic series of six magnetospheric current systems computed with the data-based semi-empirical model of Tsyganenko and Sitnov 2005 (TS05), with the measurements of four mid-latitude geomagnetic stations at very near geomagnetic latitudes, but well apart in longitude (Coimbra (COI), Portu- gal; Panagyurishte (PAG), Bulgary; Novosibirsk (NVS), Russia; Boulder (BOU), USA), and with other ground and satellite-based solar, interplanetary and geomagnetic parameters obtained from the OMNI/NASA database. An evaluation of TS05 model is presented, in order to determine the model ability to reproduce both the total magnetospheric transient signal and to explain this signal through the contribution of each TS05 magnetospheric current system at ground level, comparing them with hourly data of the four geomagnetic stations selected. It was found that TS05 model is a useful tool to explain ground-based North-South (or X) component of geomagnetic activity at mid-latitudes, in terms of main current sources. It was verified that TS05 is efficient to reproduce the X component of terrestrial magnetospheric field at mid-latitudes during high geomagnetic activity time, with correlations r ≥ 0.7 in ∼50% of compared data, presenting a lower efficiency during calm time, with correlations r ≥ 0.7 only in ∼30% of data compared. Results are less favourable for the East-West (or Y ) component, probably due to the fact that TS05 model closes Birkeland (or field-aligned, FAC) currents through the Earth’s centre instead of through the ionosphere. It was found that currents that contribute most to the X component during geomagnetic active periods are the cross-tail (TAIL), the symmetric ring (SRC) and the partial ring (PRC) currents. The currents that contribute most to Y component are FAC and PRC currents. For all stations the highest correlations among observations and TS05 simulations are obtained for stronger geomagnetic activity. The results in this study indicate that the implementation of TAIL and SRC currents in TS05 model is more successful than that for the FAC current. The quiet daily (QD) variation has a main contribution from ionospheric currents, which are not considered in TS05 model. For observatories at Northern Hemisphere’s mid-latitudes that are localized close to the ionospheric current vortex center (COI and PAG), it was possible to separate efficiently the QD ionospheric contribution using Principal Component Analysis (PCA). For the other two stations (NVS and BOU) It was found a relatively higher contribution of magnetospheric signal in the QD variation. After removing the QD variation from data, COI and PAG are better correlated with TS05 series than BOU and NVS. However, BOU and NVS are better correlated with geomagnetic indices Dst (disturbance storm-time) and RC (ring current), with RC showing a slightly less good performance with respect to Dst. Correlations between 33 solar, interplanetary magnetic field (IMF) and geomagnetic activity proxies where analysed for the 2009-2016 time interval. It was found that series of 27-day averages (Bartels’ rotation) give higher correlations than daily or annual series. Parameters that show higher cross-correlations among different groups are the Sun’s northern and southern facular areas (FA-N and FA-S), two geomagnetic indices derived from TS05 model (T-SRC and T-PRC), the total IMF intensity (B), the percentage of IMF southward component (B ZS GSM) and the interplanetary coupling Newell’s function. We propose that these parameters are the best candidates to use if we want to relate meaningfully the solar surface events to geomagnetic activity felt on the Earth’s surface. Two new proxies were tested, 1) TI-indices, calculated from the X TS05-derived series of TAIL, SRC, PRC and FAC contributions for the four observatories and 2) B ZS GSM, calculated as the daily percentage of IMF southward component along the GSM Z-axis. Helio-magnetic asymmetries were calculated for the 33 parameters, as the difference between their averaged values in the towards and away magnetic sectors of the interplanetary medium. Improvement in 27-day correlations with respect to annual correlations is the result of an annual oscillation in this asymmetry, which is present in most studied proxies and is probably due to the Russell-McPherron effect. Due to this effect, B ZS GSM and B Z GSM have a well-defined annual modulation, and GAI proxies also have annual oscillation and good correlations with B_ZS GSM and B_Z GSM. TI-indices have annual oscillation at declining phase of the cycle, but insignificant oscillation near the minimum. Major percentage of towards days in negative polarity epoch and of away days in positive polarity epoch means that the Earth has been mostly at the northern magnetic hemisphere during the solar cycle 24. In conclusion, the main part of this Ph.D. thesis was dedicated to the design and implementation of a statistical approach that was applied to test the performance of the TS05 model in explaining geomagnetic activity observed at Earth’s Northern Hemisphere mid-latitudes. This approach can be applied to test any other magnetospheric model. At the end of this work, a prospective study was made using different proxies that describe the Sun surface, the interplanetary medium and geomagnetic activity, to identify those parameters that should be more meaningfully used to relate the Sun to the geomagnetic activity observed on Earth.
Esta tese estuda os processos físicos relacionados com a atividade eomagnética detetada em observatórios magnéticos à superfície da Terra em locais de latitudes intermédias, ou seja, afastados do pólos e do equador, bem como a sua relação com a atividade solar e o meio interplanetário durante o período temporal 2007-2016. Para isto, numa primeira parte do trabalho são comparadas séries temporais simuladas, obtidas através do modelo semi-empírico de Tsyganenko and Sitnov 2005 (TS05), com as séries de dados obtidas em quatro observatórios (de latitude geomagnética próxima e espaçados em longitude) a saber: Coimbra (COI), Portugal; Panagyurishte (PAG), Bulgaria; Novosibirsk (NVS), Rússia e Boulder (BOU), USA. São ainda incluídos no estudo dados observacionais de instrumentos em Terra e no Espaço compilados na base de dados OMNI/NASA. Este estudo permite, assim, testar o modelo TS05 no que concerne a modelação das observações geomagnéticas à superfície da Terra. Os resultados apontam para que o modelo TS05 reproduz bem a componente geomagnética Norte-Sul durante os dias ativos mas é menos eficiente nos dias calmos. Por outro lado, este estudo mostra que o modelo TS05 não reproduz bem a componente Este-Oeste sendo que a causa para isso deverá ser o facto do modelo forçar o fecho das correntes Birkeland no centro da Terra e não na ionosfera. Mostra-se ainda que a componente geomagnética Norte-Sul, durante os dias ativos, é, essencialmente, influenciada pelas correntes de cauda (TAIL), a corrente de anel simétrico (SRC) e a corrente de anel parcial (PRC). Em contrapartida, a componente Este-Oeste é determinada pelas correntes FAC e PRC. As correlações entre os registos e o modelo TS05 melhoram consideravelmente nos dias geomagneticamente ativos, para qualquer um dos observatórios. Este resultado pode explicar-se pelo facto da variação magnética diurna (QD, de ‘quiet daily’) ter uma contribuição principal das correntes ionosféricas e estas não serem incluídas no modelo TS05. No caso dos observatórios localizados próximo do centro do vórtice de correntes ionosféricas (a saber COI e PAG), foi possível separar com sucesso a contribuição QD. Assim, naturalmente, após a remoção da variação QD dos dados do modelo TS05, a correlação entre o modelo e as séries de COI e PAG melhora em relação ao que ocorre em BOU e NVS. Em contrapartida os registos destes dois observatórios aparecem bem correlacionados com os índices geomagnéticos Dst (‘disturbance storm-time’) e RC (‘ring current’). Posteriormente foi feito um estudo correlacionando 33 parâmetros representativos da interação Sol-Terra no período 2009 a 2016: parâmetros solares, parâmetros do campo magnético interplanetário (IMF) e índices geomagnéticos (GAI). Mostra-se que as correlações são melhores usando médias sobre o período de rotação solar (27 dias) do que usando médias diurnas, o que sugere a necessidade de tomar em conta atrasos de propagação e efeitos cumulativos no estudo da interação Sol-Terra. A partir das médias de 27 dias, mostra-se que as correlações globais (a 33 parâmetros) são melhores para os seguintes parâmetros: áreas das regiões faculares, T-SRC e T-PRC (onde "T" indica que a grandeza foi determinada pelo modelo TS05 - índices TI), o módulo do vector do campo IMF, a percentagem sul de IMF (BZS GSM) e a função de Newell, de acoplamento vento solar/magnetosfera. Por outro lado, foram calculadas as assimetrias helio-magnéticas decorrentes da diferença entre os valores médios dos parâmetros durante o trânsito através dos setores de polaridade solar positiva e negativa do meio interplanetário. Da análise das referidas assimetrias constata-se que a Terra esteve, durante o ciclo 24, mais tempo a norte do que a sul do equador solar. Além disso, as assimetrias põem em evidência uma oscilação anual presente nas séries de BZS GSM, BZ GSM e nos índices GAI e explicada em princípio pelo efeito de Russell-McPherron. Nota-se ainda uma variação anual dos índices TI durante a fase descendente do ciclo solar. Em conclusão, a maior parte do trabalho desta tese foi ocupada com a implementação de uma série de testes estatísticos aplicados ao estudo do desempenho do modelo TS05 na simulação da atividade geomagnética observada a latitudes intermédias do Hemisfério Norte. O esquema de testes aqui proposto pode no futuro ser aplicado a qualquer outro modelo da magnetosfera. No final deste trabalho, realizou-se ainda uma pesquisa envolvendo diferentes parâmetros que caraterizam a superfície do Sol, o meio interplanetário e a atividade geomagnética, com o intuito de identificar os mais adequados a ser utilizados para relacionar fenómenos à superfície do Sol com a atividade geomagnética observada na Terra.
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Becker, Jens Karl. "The emplacement of the Chinamora Batholith (Zimbabwe) inferred from field observations, magnetic- and microfabrics." Doctoral thesis, 2000. http://hdl.handle.net/11858/00-1735-0000-0006-B35F-B.
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