The evolution and propagation of solar transients through the heliosphere

• Main Author: Prise, A. J.
• Published: University College London (University of London) 2015
• Subjects: 523.7
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.677684

There are several different transient structures that propagate in the solar wind, including Coronal Mass Ejections (CMEs), Solar Energetic Particles (SEPs) and Co-rotating Interaction Regions (CIRs). A CME is an explosion of plasma and magnetic field from the Sun’s corona. SEPs are high energy particles, produced directly by solar flares, or accelerated ahead of a shock associated with CMEs. CIRs are large scale structures in the solar wind, which arise from the interaction between fast solar wind as it catches up with slow solar wind. All these phenomena are capable of driving significant space weather effects on the Earth. This thesis studies the evolution and propagation of these different structures through the heliosphere, by making use of remote sensing, in-situ, and planetary data, as well as solar wind modelling. Widespread energetic particles associated with a CME were studied, and the longitudinal range of the particles connected with the lateral expansion of the CME. As the CME expands, it connects with more field lines on the Parker spiral, allowing the SEPs to propagate out across a wider range of longitudes. As CMEs are one of the most significant drivers of space weather, it is important to study how they evolve as they propagate. Multipoint observations and solar wind modelling of a CME and preceding CIR are used to study how both transients propagate and interact. The structures merge beyond the inner solar system and the impacts of the resulting structure are observed at Saturn. The ENLIL solar wind model is then analysed in more detail, by comparing the model outputs with multipoint in-situ data at 1 AU. Different initial conditions for the model were set up, including different magnetograms and coronal models. The variation of the model output with the addition of several CMEs were also studied.