No description available.

No description available.

Determination of Earth geomagnetic field parameters and research of their variation is an actual and complex problem of natural science. It is related to knowledge of the state of natural physical system outer parameters of present geophysical and geodynamical processes. Variation of geomagnetic field is continuous process evident in different Earth surface places but in different ways. It can be determined by precise measurements. Precise repeated observations of geomagnetic field parameters at repeat stations is one of basic methods. For determination of certain epoch geomagnetic field parameters, detailed information on geomagnetic field and its variations is necessary. Data of geomagnetic field research is used for solution of different theoretical and practical tasks. Data is important for solving tasks of navigation, geophysics, geodynamics, explorations of minerals. According requirements of NATO and ICAO (International Civil Aviation Organization) – parameters of geomagnetic field are presented on the topographic maps and navigation charts of the air ports. Compass or director is used in geodesy for orientation, when instrument arrow is oriented along lines of geomagnetic field. Information on geomagnetic declination is necessary for direction determination in this case. Value of declination and its annual change is presented on topographical maps. Geomagnetic and gravimetric data are useful for exploration of minerals. Gravity value and geomagnetic induction help us... [to full text]

Determination of Earth geomagnetic field parameters and research of their variation is an actual and complex problem of natural science. It is related to knowledge of the state of natural physical system outer parameters of present geophysical and geodynamical processes. Variation of geomagnetic field is continuous process evident in different Earth surface places but in different ways. It can be determined by precise measurements. Precise repeated observations of geomagnetic field parameters at repeat stations is one of basic methods. For determination of certain epoch geomagnetic field parameters, detailed information on geomagnetic field and its variations is necessary. Data of geomagnetic field research is used for solution of different theoretical and practical tasks. Data is important for solving tasks of navigation, geophysics, geodynamics, explorations of minerals. According requirements of NATO and ICAO (International Civil Aviation Organization) – parameters of geomagnetic field are presented on the topographic maps and navigation charts of the air ports. Compass or director is used in geodesy for orientation, when instrument arrow is oriented along lines of geomagnetic field. Information on geomagnetic declination is necessary for direction determination in this case. Value of declination and its annual change is presented on topographical maps. Geomagnetic and gravimetric data are useful for exploration of minerals. Gravity value and geomagnetic induction help us... [to full text]

No description available.

No description available.

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

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.

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.

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.