Multi-instrument and modelling studies of ionospheres at Earth and Mars

• Main Author: Grandin, Maxime
• Other Authors: Institut de recherche en astrophysique et planétologie (IRAP), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales Toulouse (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales Toulouse (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France-Centre National de la Recherche Scientifique (CNRS), Université Toulouse 3 Paul Sabatier (UT3 Paul Sabatier), Alexander Kozlovsky, Aurélie Marchaudon, Anita Aikio, Thomas Ulich
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: HAL CCSD 2017
• Subjects: auroral ionosphere; ionosphere–magnetosphere coupling; solar wind high-speed streams; Martian atmosphere and ionosphere; radio-occultation; ionosphère aurorale; couplages ionosphère–magnétosphère; courants de vent solaire rapide; atmosphère et ionosphère martiennes; [SDU.ASTR.EP]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP]; [SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph]; Ionosphère; Sodankylä
• Online Access: https://theses.hal.science/tel-01636840; https://theses.hal.science/tel-01636840/document; https://theses.hal.science/tel-01636840/file/Grandin_PhDthesis.pdf

This thesis is based on five publications studying the terrestrial and Martian ionospheres by making use of versatile instruments and of modelling techniques. The terrestrial ionosphere is a complex system strongly coupled to the magnetosphere and hence very sensitive to solar wind driving. Various kinds of instruments may be used to study the ionosphere, from ground-based instruments to satellite-borne systems. Two papers study the response of the auroral and subauroral ionosphere to solar wind high-speed streams, which originate from coronal holes at the surface of the Sun. These two studies make use of the superposed epoch analysis method, which enables to derive the statistical behaviour of the studied parameters. For the first study, which focuses on the F-region peak electron density measured by the Sodankylä ionosonde (at L = 5.2), the superposed epoch method has been modified so that a study of the effects of high-speed streams in the F region in different magnetic local time sectors becomes possible. The modified method is called phase-locked superposed epoch analysis. The second paper focuses on energetic (>30 keV) electron precipitation during high-speed streams by making use of cosmic noise absorption measurements from a chain of riometers located between L = 3.8 and L = 5.7. A third study reveals for the first time pulsation signatures in cosmic noise absorption data during a pulsating aurora event. This indicates that the electron precipitation flux is modulated simultaneously over a broad range of energies (from a few keV to several tens of keV) in relation to pulsating aurora. The fourth and fifth articles study the Martian ionosphere. They present a novel analysis method for Mars Express radio-occultation data. Contrary to the classical inversion approach, this new method is based on a direct simulation of the radio wave propagation between the ground-based station at Earth and the Mars Express spacecraft, in a modelled Martian environment. The parameters determining the properties of the ...