Studies of the Solar Wind with Interplanetary Scintillation

  • Stuart Adam Hardwick

Student thesis: Doctoral ThesisDoctor of Philosophy


The Sun is at the centre of our solar system and it is constantly ejecting a flow of plasma outward into interplanetary space. This flow can take the form of two primary types; the fast solar wind; and the slow solar wind. The Sun may also eject plasma with more dynamic events which cause high density clouds of plasma to travel alongside the solar wind. In the modern world, a number of different techniques have been developed to study the solar wind from the Earth and also in interplanetary space. Interplanetary scintillation (IPS) is a technique that has been applied at Aberystwyth University to observe the continual density variations in the solar wind by observing a distant astronomical radio source and the scintillation of its radio waves as they pass through the solar wind. To perform this, a number of radio sites around the world have been used such as the European Incoherent SCATter radar (EISCAT) in northern Scandinavia, and the ever growing LOw Frequency ARray (LOFAR) based in the Netherlands. The IPS technique has also proved to be highly complementary with Heliospheric Imagers (HIs) onboard the Solar TErrestrial RElations Observatory (STEREO) spacecraft which detect the white light which has been scattered by the solar wind particles. This thesis investigates the solar wind using a wide variety of techniques to observe the small- and large-scale structures which form in the solar wind. A study of IPS in 2007 and 2008 detected numerous events of rapid velocity variations which occurred in the slow solar wind. This showed evidence that the slow solar wind may have a ‘blobular’ nature formed of many small-scale transients as well as the large-scale transients which are already well known to us. In November 2011 LOFAR observed its first coronal mass ejection (CME) while observing IPS. This event proved to become of interest as it was successfully detected by a number of different techniques and could modeled and tracked accurately as it propagated outward to Earth’s orbit and even interacted with the Earth’s magnetosphere. A technique which could be applied to coronagraph observation separated the dynamic and quiescent solar wind structures from the images. The quiescent component became the basis for the development of a new solar wind model which could quickly and accurately map the background quiescent solar wind free from any of the complexities cause by CMEs
Date of Award17 Feb 2016
Original languageEnglish
Awarding Institution
  • Aberystwyth University
SponsorsScience and Technology Facilities Council
SupervisorMario Mark Bisi (Supervisor) & Huw Morgan (Supervisor)

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