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University of Oulu

1. Ruopsa, M. (Miro). Connection of energetic electron precipitation to solar wind and geomagnetic activity.

Degree: 2018, University of Oulu

Abstract The subject of the thesis was the analysis of energetic electron precipitation (EEP) using principal component analysis (PCA) as well as how the EEP connects to geomagnetic activity and solar wind parameters. Electrons which cause the electron precipitation end up in the Earth's magnetosphere mainly from the solar wind. Due to different mechanisms they can drift into a so called loss cone and follow the magnetic field lines close enough to Earth's atmosphere to collide with the atmospheric particles and cause the precipitation. The effect of EEP to geomagnetic activity is important to understand to be able to model the long term evolution of the EEP from the 19th century to present. EEP has also been shown to have an effect on the weather of Earth's polar regions and thus the results could also be used in climate studies. The EEP data used in thesis are from the Polar-orbiting Operation Environmental Satellites (POES) of the National Oceanic and Atmospheric Administration (NOAA). The data have been corrected of several issues including, e.g., detector degradation, proton contamination, magnetic local time (MLT) drift, cosmic ray contamination and satellite telescope orientation difference induced. The total latitudinal range covered in the analysis goes from 40 degrees to 88 degrees within each of the hemispheres. Three different integral energy channels were analyzed separately, which were E1 (E > 30 keV), E2 (E > 100 keV) and E3 (E > 300 keV). The solar wind and geomagnetic data (except aa index) were provided by NASA’s OMNIweb online interface. British Geological Survey provided the aa index and a catalog of solar wind flow types were provided by Ian Richardson and Hilary Cane (2012). PCA reveals at least 5 underlying modes (factor loadings) from the EEP data. The modes seem to represent the geomagnetic variations, solar energetic proton event (SEP) related variations and/or CME-related variations, modes that follow the CME and HSS fractions in the solar wind, annual variations and semi-annual variations. Furthermore, a minor variation mode that might correspond to the remnants of the SEM-1 and SEM-2 detector difference induced data inhomogeneity was found. The results improve the understanding of the connection between EEP and solar wind and geomagnetic activity. The results could be used, e.g., to help estimating the evolution of the EEP in the past.

Tiivistelmä Opinnäytetyön tarkoitus oli analysoida energeettistä elektronisadantaa (Energetic electron precipitation, EEP) hyödyntäen pääkomponenttianalyysia (PCA). Elektronit, jotka aiheuttavat lopulta elektronisadannan päätyvät Maan magnetosfääriin pääosin aurinkotuulesta. Hiukkaset voivat eri mekanismien seurauksena…

Subjects/Keywords: Physics

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APA (6th Edition):

Ruopsa, M. (. (2018). Connection of energetic electron precipitation to solar wind and geomagnetic activity. (Masters Thesis). University of Oulu. Retrieved from http://urn.fi/URN:NBN:fi:oulu-201805312357

Chicago Manual of Style (16th Edition):

Ruopsa, M (Miro). “Connection of energetic electron precipitation to solar wind and geomagnetic activity.” 2018. Masters Thesis, University of Oulu. Accessed June 23, 2018. http://urn.fi/URN:NBN:fi:oulu-201805312357.

MLA Handbook (7th Edition):

Ruopsa, M (Miro). “Connection of energetic electron precipitation to solar wind and geomagnetic activity.” 2018. Web. 23 Jun 2018.

Vancouver:

Ruopsa M(. Connection of energetic electron precipitation to solar wind and geomagnetic activity. [Internet] [Masters thesis]. University of Oulu; 2018. [cited 2018 Jun 23]. Available from: http://urn.fi/URN:NBN:fi:oulu-201805312357.

Council of Science Editors:

Ruopsa M(. Connection of energetic electron precipitation to solar wind and geomagnetic activity. [Masters Thesis]. University of Oulu; 2018. Available from: http://urn.fi/URN:NBN:fi:oulu-201805312357

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