The primary objective of this research is to investigate the viability of magnetic anomaly localization with an autonomous underwater vehicle, using a genetic algorithm (GA). The localization method, first proposed by Sheinker. et al. 2008, is optimized here for the case of a moving platform. Extensive magnetic field modeling and algorithm simulation has been conducted and yields promising results. Field testing of the method is conducted with the use of the Ocean Floor Geophysics Self-Compensating Magnetometer (SCM). Extensive out-of-water field testing is conducted to validate the ability to measure a target signal in a uniform NED frame as well as to validate the effectiveness of the GA. The outcome of the simulation closely matches the results of the conducted field tests. Additionally, the SCM is fully integrated with FAU’s Remus 100 AUV and preliminary in-water testing of the system has been conducted. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2017. / FAU Electronic Theses and Dissertations Collection

Geomagnetic storms deposit energy and momentum into the Earth’s magnetosphere which in turn energizes the terrestrial atmosphere through Joule heating and particle precipitation. This storm energy predominantly converges at altitudes of 100 to 150 km, corresponding to the lower thermospheric region, which is then globally redistributed throughout the thermosphere. It is essential that we understand the times and magnitudes of this energy to understand the terrestrial atmospheric response to geomagnetic storms. However, our current knowledge is mostly limited to the studies of orbital altitudes of the thermosphere. We aim to fill this gap by conducting a statistical study of lower thermospheric response to geomagnetic storms. We use neutral temperature data from SABER (Sounding of the Atmosphere Using Broadband Emission Radiometry) instrument onboard the TIMED (Thermosphere, Ionosphere, and Mesosphere Energy Dynamics) satellite for this study. We devise a procedure to extract the storm response from SABER temperature measurements and deduce the magnitudes and times of the global storm energy redistribution in the 100 to 120 km altitude of the thermosphere. We use methods of inferential and descriptive statistics to investigate the lower thermospheric response for 145 storm intervals that occurred between 2002 and 2010. We also investigate the performance of the state-ofart physics and empirical models in replicating the lower thermosphere during geomagnetic storms.

Terrestrial auroras are visible-light events caused by charged particles trapped by the Earth's magnetic eld precipitating into the atmosphere along magnetic eld lines near the poles. Auroral events are very dynamic, changing rapidly in time and across large spatial scales. Better knowledge of the low of energy during an aurora will improve understanding of the heating processes in the atmosphere during geomagnetic and solar storms. The Auroral Spatial Structures Probe is a sounding rocket campaign to observe the middle-atmosphere plasma and electromagnetic environment during an auroral event with multipoint simultaneous measurements for fine temporal and spatial resolution. The auroral event in question occurred on January 28, 2015, with liftoff the rocket at 10:41:01 UTC. The goal of this thesis is to produce clear observations of the magnetic eld that may be used to model the current systems of the auroral event. To achieve this, the attitude of ASSP's 7 independent payloads must be estimated, and a new attitude determination method is attempted. The new solution uses nonlinear least-squares parameter estimation with a rigid-body dynamics simulation to determine attitude with an estimated accuracy of a few degrees. Observed magnetic eld perturbations found using the new attitude solution are presented, where structures of the perturbations are consistent with previous observations and electromagnetic theory.

ECRS is a program for the detailed simulation of extensive air shower initiated by high energy cosmic ray particles. In this dissertation work, a Geant4 based ECRS simulation was designed and developed to study secondary cosmic ray particle showers in the full range of Earth's atmosphere. A proper atmospheric air density and geomagnetic field are implemented in order to correctly simulate the charged particles interactions in the Earth's atmosphere. The initial simulation was done for the Atlanta (33.460 N , 84.250 W) region. Four different types of primary proton energies (109, 1010, 1011 and 1012 eV) were considered to determine the secondary particle distribution at the Earth's surface. The geomagnetic field and atmospheric air density have considerable effects on the muon particle distribution at the Earth's surface. The muon charge ratio at the Earth's surface was studied with ECRS simulation for two different geomagnetic locations: Atlanta, Georgia, USA and Lynn Lake, Manitoba, Canada. The simulation results are shown in excellent agreement with the data from NMSU-WIZARD/CAPRICE and BESS experiments at Lynn Lake. At low momentum, ground level muon charge ratios show latitude dependent geomagnetic effects for both Atlanta and Lynn Lake from the simulation. The simulated charge ratio is 1.20 ± 0.05 (without geomagnetic field), 1.12 ± 0.05 (with geomagnetic field) for Atlanta and 1.22 ± 0.04 (with geomagnetic field) for Lynn Lake. These types of studies are very important for analyzing secondary cosmic ray muon flux distribution at the Earth's surface and can be used to study the atmospheric neutrino oscillations.

Archaeomagnetism is an area of research that utilises the magnetic properties of archaeological materials to date past human activity. This research aimed to use the evidence of past geomagnetism, as recorded by archaeological and geological materials, to identify and characterise short timescale changes in the Earth¿s magnetic field. This contribution to the discipline focused on the first millennium BC, as there is evidence that during this time the Earth¿s magnetic field experienced rapid changes in direction. This work focused on an established weakness in archaeomagnetic studies, i.e. the application of archaeological information to assign a date range to the magnetic directions. The date ranges for 232 magnetic directions from 98 Iron Age sites were reviewed and a programme of fieldwork produced 25 new magnetic directions from 11 Iron Age sites across Britain. The approach developed in this thesis has made significant improvements to the data examined, which represent the prehistoric section of the British secular variation curve (SVC). These data have been incorporated into the British archaeomagnetic dataset that now comprises over 1000 magnetic directions and will be used to generate future British SVCs. The potential of the near continuous records of geomagnetic secular variation from British lake sediment sequences to SVCs was explored. This showed that these sediments have recorded the relative changes in the Earth¿s magnetic field but the dating and method of constructing the British master curve requires revision. As SVCs are predominately used as calibration curves for archaeomagnetic dating, this work provides a foundation for a revised and extended British SVC. This revision would be to the mutual benefit of studies in archaeology and archaeomagnetism, as the latter could potentially enable highresolution dating of Iron Age material, providing a viable alternative to radiocarbon dating.

No description available.

In this thesis we examine the generation mechanisms of Pc 5 ULF waves during geomagnetic storms. Also, we study the interaction between Pc 5 ULF waves and energetic particles in the radiation belts and the observed energetic particle flux modulation by Pc 5 ULF waves is verified using particle simulations. Firstly, we present case studies of Pc 5 pulsations using ground-based magnetometer and satellite data during geomagnetic storm times, specifically we selecting three storm time events which show a brief increase in Dst in the main phase of the storms. By studying these events, we attempt to identify the generation mechanisms responsible for the geomagnetic pulsations. The observed pulsations exhibit the characteristic features of a Field Line Resonance. Our results also show evidence for the penetration of ULF wave power in the Pc 5 band to much lower L-shells than normal, suggesting significant reduction of the local Alfven eigenfrequency continuum as compared to non-storm times. This may have considerable significance for the interaction between ULF waves and MeV electrons in the outer radiation belt during storms. Secondly, based on the hypothesis that Pc 5 ULF waves may play an important role in energetic particle dynamics in the radiation belt and ring current, we investigated the relationship between Pc 5 pulsations and energetic particle flux oscillations. We observed very strong Pc 5 oscillations during the great magnetic storm of March 24, 1991 [Lee et al., 2007] and electron flux simultaneously oscillating with the same frequencies in the time domain. We also characterize two more events and present an examination of the relationship between the electron flux modulation and Pc 5 ULF pulsations. Based on our observations, the modulation of energetic particles might be associated with a drift-resonance interaction, or the advection of an energetic particle density gradient. Finally, we numerically calculate the trajectories and energy change of charged particles under the influence of model ULF wave electric fields. This modeling work is used to help to explain the observations and provides evidence which supports the modulation mechanisms such as advection of a flux gradient and drift resonance.

Thesis (MEng)--Stellenbosch University, 2015. / ENGLISH ABSTRACT: In 2012, a three-axis HTS-SQUID magnetometer project for geomagnetic measurements has been started at SANSA Space Science in Hermanus, South Africa. The goal of this project was to replicate a three-axis SQUID magnetometer for geomagnetic field measurements at LSBB at Rustrel, France. This is to allow better characterizing of faint, low frequency geomagnetic and ionospheric phenomena. To record the output signals of the SQUID magnetometers, a measurement system had to be developed. To utilise the full sensitivity of the SQUID magnetometers, the output signals have to be recorded with high accuracy. A high-speed and high-accuracy data acquisition system was installed and software was developed to record data from it. The software is capable of sending the recorded data to a web server as it is being recorded. Basic hardware control of the SQUID magnetometers has also been implemented from this data acquisition system, by monitoring conditions with its software. Timing accuracy is an important aspect of this system, in order to enable comparisons with measurements from LSBB and from different locations in the world. A GPS receiver was used to obtain the current UTC time accurately in order to timestamp measurements. A software method was devised for timestamping, to improve accuracy by triggering measurements directly from the GPS receiver. A hardware real-time clock between the GPS receiver and the rest of the system has been avoided using this method. For research purposes, this measurement data must be available on the internet for the lifetime of the system. A data server was set up and a large database of recorded data has been generated over two years of this project. Long term implementation issues have also been addressed. A web interface was developed for the data server to enable live viewing of the recorded data. This web interface also facilitates access to the raw measurements for public use. Analysis of phenomena in the recorded data has been performed by other students from Stellenbosch University. / AFRIKAANSE OPSOMMING: In 2012 is daar by SANSA Space Science in Hermanus, Suid-Afrika begin met 'n drie-as HTS-SQUID magnetometerprojek vir die opneem van geomagnetiese metings. Die doel van hierdie projek was om die drie-as SQUID magnetometer vir geomagnetiese veldmetings by LSBB naby Rustrel in Frankryk te dupliseer. Dit sou dit moontlik maak om subtiele, laefrekwensie geomagnetiese en ionosferiese verskynsels beter te beskryf. Om die uittreeseine wat deur die SQUID magnetometers voortgebring word op te neem, moes n data-opnemerstelsel ontwikkel word. Ten einde die volle sensitiwiteit van die SQUID magnetometers te benut, moes die seine baie akkuraat gemeet word. 'n Hospoed- en ho-akkuraatheidsdata-opnemer is genstalleer en die nodige sagteware is ontwikkel om hierdie data op te neem. Die sagteware is in staat om die data, soos dit opgeneem word, na 'n webbediener te stuur. Basiese hardewarebeheer van die SQUID magnetometers is ook vanaf hierdie data-opnemerstelsel gemplementeer deur toestande met die sagteware te monitor. Akkurate tydmeting is 'n belangrike aspek van hierdie sisteem, sodat metings met die van LSBB en ander soortgelyke projekte in ander posisies op die aarde vergelyk kan word. 'n GPS-ontvanger is gebruik om die UTC-tyd akkuraat te ontvang, ten einde akkurate tydstempeling by metings te voeg. 'n Sagtewaremetode vir tydstempeling is ontwikkel om akkuraatheid te bevorder deur metings direk vanaf die GPS-ontvanger te sneller. Deur hierdie metode te gebruik, is dit onnodig om n intydse hardewaretydhouer tussen die GPS-ontvanger en die res van die sisteem te gebruik. Vir navorsingsdoeleindes moet hierdie metingsdata op die internet beskikbaar wees vir die duur van die stelsel se leeftyd. 'n Databediener is opgestel en 'n baie groot databasis van opgeneemde data is oor die twee jaar van hierdie projek gegenereer. Langtermynimplementeringskwessies het ook aandag geniet. 'n Webblad is vir die databediener ontwikkel sodat die data onmiddellik besigtig kan word soos dit opgeneem word. Hierdie webblad fasiliteer ook toegang tot die rou data-opnames vir openbare gebruik. Verskynsels in die data-opnames is by SANSA geanaliseer deur ander studente van die Universiteit van Stellenbosch.

Made available in DSpace on 2014-06-11T19:30:31Z (GMT). No. of bitstreams: 0 Previous issue date: 2007-02-28Bitstream added on 2014-06-13T21:01:19Z : No. of bitstreams: 1 matsuoka_mt_dr_prud.pdf: 13818049 bytes, checksum: ffbf4629b778855c81e385452f044bfb (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Após a desativação da técnica SA, a ionosfera tornou-se a principal fonte de erro no posicionamento com GPS. O erro associado à ionosfera é diretamente proporcional ao conteúdo total de elétrons (TEC - Total Electron Content) presente ao longo do caminho da trajetória percorrida pelo sinal na ionosfera e inversamente proporcional ao quadrado da freqüência do sinal. O TEC, e conseqüentemente o erro devido à ionosfera, variam no tempo e no espaço e é influenciado por diversas variáveis, tais como: ciclo solar, época do ano, hora do dia, localização geográfica, atividade geomagnética, entre outros. A região brasileira é um dos locais que apresenta os maiores valores e variações espaciais do TEC e onde estão presentes diversas particularidades da ionosfera, tais como, a anomalia equatorial e o efeito da cintilação ionosférica. Desta forma, é importante a realização de pesquisas que visam estudar o comportamento do TEC, e conseqüentemente do erro devido à ionosfera no Brasil, que é um trabalho complexo devido aos diversos fatores que influenciam a variação do TEC, além das particularidades presentes na região brasileira. Estudos desta natureza podem auxiliar a comunidade geodésica brasileira, e demais usuários do GPS, no entendimento das limitações impostas pela ionosfera nas regiões de interesse. Devido à natureza dispersiva da ionosfera, o estudo do comportamento do TEC no Brasil pode ser realizado utilizando os dados GPS de receptores de dupla freqüência pertencentes à RBMC (Rede Brasileira de Monitoramento Contínuo). Adicionalmente, para uma melhor análise, pode-se também utilizar dados das estações da rede IGS (International GNSS Service) da América do Sul. / In the SA absence, the ionosphere is the largest error source in GPS positioning. The error due to the ionosphere in the GPS observables depends on the signal frequency and Total Electron Content (TEC) in the ionospheric layer. The TEC varies regularly in time and space in relation to the sunspot number, the season, the local time, the geographic position, and others. The Brazilian region is one of the regions of the Earth that presents largest values and space variations of the TEC, being influenced by the equatorial anomaly of ionization and ionospheric scintillation. Therefore, it is important to study the TEC behavior in the Brazilian region. Due to the ionosphere dispersive nature, the TEC behavior in Brazil can be studied using GPS data from RBMC (Rede Brasileira de Monitoramento Contínuo - Brazilian Network for Continuous Monitoring of GPS). Additionally, GPS data from IGS (International GNSS Service) network of the South America can also be used in the experiments.

Ce travail porte sur l’anomalie de l’Atlantique Sud (SAA anglais). Nous avons étudié cette anomalie du champ magnétique principal à partir de données satellitaires afin de mieux connaître les différentes sources de ses variations temporelles. Nous avons appliqué l’analyse en composantes principales (PCA) à des données de flux de particules, de bruit d’un lidar embarqué et à des séries temporelles d’observatoires magnétiques virtuels - séries construites à partir de mesures satellitaires du champ géomagnétique. Les données de flux de particules proviennent de trois satellites de la série POES de la NOAA (POES 10, 12 et 15) ainsi que du satellite Jason-2 du CNES et de la NASA. Nous utilisons aussi le bruit affectant le lidar CALIOP du mini-satellite CALIPSO (CNES/NASA) comme substitut au flux de particules chargées heurtant ce satellite. Pour l’information géomagnétique, deux jeux de données d’observatoires virtuels construits à partir d’enregistrements des satellites CHAMP et Swarm ont été utilisés. Ces deux ensembles différents de données apportent des éclairages complémentaires sur l’anomalie de l’Atlantique Sud. L’analyse en composantes principales des données de flux de particules a permis de distinguer différents modes de variabilité, dus au soleil d’une part et au champ magnétique principal d’autre part. Le cycle solaire de 11 ans affecte à la fois le flux total de particules énergétiques à l’aplomb de l’anomalie de l’Atlantique Sud et leur distribution dans les différentes ceintures de radiation internes. Le champ magnétique principal, qui provient du noyau liquide de la Terre, est responsable d’une lente dérive de l’anomalie de l’Atlantique Sud et par ricochet de la région où il y a un flux intense de particules énergétiques. Une fois déconvolué le rôle du champ magnétique principal, on distingue deux composantes que l’on peut associer sans ambiguïté au cycle solaire. Sur des temps plus longs, nous avons finalement pu mettre en évidence une tendance dans le flux total de particules dans la région de l’Atlantique Sud. Peu d’analyses globales des modes de variabilité du champ interne ont été entreprises. Notre étude vise aussi à combler ce manque. L’analyse en composantes principales permet d’extraire jusqu’à trois modes d’origine interne et un mode annuel combinant contributions interne et externe. Ce dernier mode a une géométrie principalement quadrupolaire et zonale. Le premier des modes purement internes explique l’essentiel de la variabilité du champ et correspond à la variation séculaire moyenne au cours de l’intervalle de temps étudié. Il s’interprète principalement comme la variation de la partie du champ géomagnétique représentée par un dipôle qui serait de plus en plus décalé par rapport au centre de la Terre en direction de l’Asie du Sud-Est et qui serait aussi incliné par rapport à l’axe de rotation. Ainsi, ce simple modèle nous a été utile à la fois pour rendre compte du flux de particule au dessus de l’anomalie de l’Atlantique Sud et pour interpréter la variation du champ géomagnétique à l’échelle globale. / This work focus on the study of the South Atlantic Anomaly (SAA) of the main magnetic field from satellite data, aiming at identifying different sources of variability. This is done by first applying the Principal Component Analysis (PCA) method to particle flux and dark noise data and then to Virtual Observatories (VOs) time series constructed from satellite magnetic records. Particle flux data are provided by three POES NOAA satellites (10, 12 and 15) and the Jason-2 satellite. Dark noise data, which can be interpreted as a proxy to particle flux, are provided by the CALIOP lidar onboard the CALIPSO satellite. The magnetic field information is used in the form of time series for VOs, which were computed from both CHAMP and Swarm data as two separate datasets. The two different groups of data provide different views of the South Atlantic Anomaly. Applying PCA to particle flux data on the SAA produces interesting modes that can be related with specific physical processes involved with the anomaly. The main sources that drive these modes are the Earth’s magnetic field and the Sun. The Sun’s 11-year cycle is a well-known quasi-period of solar activity. This work shows how it clearly affects the evolution of the energetic particles trapped in the inner Van Allen belt, by modulating both their total number and their distribution among different L-shells. The way particles become trapped and move near-Earth is also dictated by the main magnetic field geometry and intensity and so a good understanding of its variation allows for a better description of the evolution of these particles. The main magnetic field, with origin in the Earth’s liquid core, is responsible for a slow drift of the anomaly, associated to the Westward drift of several features of the main field. Changing the frame of reference to that of the eccentric dipole, we were able to identify two separate modes associated with the variability of the solar activity. On longer time-scales, we also observed a linear trend in the spatial evolution of the particle flux. A global analysis of variability modes of the Earth’s magnetic field has not been often addressed. This study also contributes to fill this gap. By decomposing satellite records of the magnetic field into PCA modes, we retrieved modes of internal origin and modes with large external contributions, with no a-priori considerations. An annual signal has been identified and associated with mainly external sources. It exhibits an interesting geometry dominated by a zonal quadrupolar geometry. As for the internal source, three separate modes were obtained from the longest time series analysed. The first of these modes explains most of the variability of the field and represents the mean secular variation. It is closely modelled by an eccentric tilted dipole moving away from the Earth’s center and toward under East Asia. As this study shows, this simple model turns out to be a useful tool that can be used both on regional studies of the SAA and on global studies of the geomagnetic field.