Unit:
Department of PhysicsLibrary of the School of Science
Supervisors info:
Επιβλέπων
Καθ. Ιωάννης Α. Δαγκλής
Καθηγητής, Τομέας Αστροφυσικής, Αστρονομίας Και Μηχανικής, Τμήμα Φυσικής, ΕΚΠΑ
Συνεπιβλέπων
Δρ. Γεώργιος Μπαλάσης
Διεθυντής Ερευνών, Ινστιτούτο Αστρονομίας, Αστροφυσικής, Διαστημικών Εφαρμογών και Τηλεπισκόπησης, Εθνικό Αστεροσκοπείο Αθηνών
Original Title:
Μελέτη της αναπαράστασης των ιονοσφαιρικών και μαγνητοσφαιρικών πηγών στα μοντέλα του μαγνητικού πεδίου της Γης, με χρήση μετρήσεων του επίγειου δικτύου μαγνητομέτρων ENIGMA
Translated title:
Study of the representation of ionospheric and magnetospheric sources, concerning the models of the geomagnetic field with the use of measurements taken by the enigma ground-based magnetometer network.
Summary:
The purpose of the thesis is the study of the representation of ionospheric and magnetospheric sources, concerning the models of the geomagnetic field with the use of measurements taken by the enigma ground-based magnetometer network. In order to compare the results, we also use measurements from two magnetometer ground-based stations outside of Greece, that are located in mid and high latitudes.
It should also be noted that the following project is the first attempt to process and apply models of the magnetic field on the ENIGMA data.
The magnetic field is being produced by the liquid and conductive core of the Earth. Magnetizing rocks and induced currents in the interior also contribute to the overall strength and changes of the field, while the Earth's interaction with the solar wind leads to additional components of the field. Additionally, the rotation of the earth as well as its movement in relation to the ones of the sun and moon create periodic fluctuations at the strength of the field.
The complicated nature of the magnetic field can be described by several models that focus on either all or individual contributing factors.
This thesis is focused on three fundamental components: The one of the core, the ionosphere and the one concerning external sources.
Two widespread models are used, namely IGRF 12 and CHAOS 6. The first one describes the field produced by the core and the crust of the earth, while the second one describes the field produced by the core and the field of three sources coming from the magnetosphere: the ring current, the magnetopause and the magnetotail. Additionally, a simple method is used with which we isolate and extract from the time series of the data the daily change caused by the Sq current of the ionosphere.
In chapter 1 certain basic theory aspects are presented to help the understanding of this thesis. The processes causing and maintaining the earth's magnetic field are being assessed, as well as the sources of its time variation.
Furthermore, the models used are thoroughly presented.
In chapter 2 the basic characteristics of the stations used are mentioned as well as the method of the initial data analysis. The method with which the errors of the enigma raw data were dealt with is also described.
In chapter 3 the further data analysis with the model use is explained, followed by chapter 4 describing the extraction of the daily variation caused by the Sq current.
At the end of chapters 2 3 and 4 respectively, a brief report of the conclusions reached for each process followed by commentary is presented.
Finally, at the end of chapter 5, the conclusions of the whole project are thoroughly apposed.
Main subject category:
Science
Keywords:
magnetic field, magnetosphere, ionosphere, secular variation, magnetic storms, solar quiet, models, temporal variation, CHAOS, IGRF, enigma
