Coupling of upstream solar wind features to dayside auroral ionospheric events

Throp, Katie (2005) Coupling of upstream solar wind features to dayside auroral ionospheric events. University of Southampton, Doctoral Thesis.

Record type: Thesis (Doctoral)

Abstract

An multi-instrument investigation into the characterisation response of the global Magnetospheric-Ionospheric system to variations in upstream solar wind parameters. A method of determining the propagation time is developed to couple transient variations in solar wind pressure and IMF orientation to aurorol ionospheric signatures observed by a range of ground-based and satellite-borne instruments.

Three events are studied, chosen in order to examine the individual and combined impact of the two upstream features on the ionosphere. The first event is characterized by two brief swings of the interplanetary magnetic field (IMF) towards a southwind orientation. Modelling is used to fit observed variations in the peak proton emission intensity and reproduce the spatial distribution of the proton emission observed by a range of instruments. The second event sees a brief southward IMF turning accompanied by an increase in the solar wind dynamic pressure. Filtering is used as an effective method of separating the slow convection variations from the higher frequency pressure front effects, providing a way of interpreting both the ground-based data and model results. The third event is characterized by a rapid increase in the upstream solar wind pressure during a period of northward IMF. Filtering reveals pressure front signatures comparable to the second event and evidence of enhanced high-latitude convection effects.

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