Statistics of e-region backscatter and investigations of auroral convection signatures.
thesisposted on 19.11.2015, 09:17 by Brian A. Shand
In this thesis data from the Sweden And Britain Radar Experiment is examined in a statistical investigation of the variation of the radar backscatter amplitude due to variations in the ionospheric convection. The response of the radar backscatter is examined over an eight year interval from 1982 until 1989 and a strong dependence of the variation of the backscatter amplitude on flow direction and magnitude determined during the solar cycle. The results are discussed with reference to three geophysical parameters which control the relationship between the backscatter intensity and Doppler velocity, namely the ambient electron density, the electron density fluctuation amplitude and the dimensions of the scattering layer. Data from the SABRE system is further utilised in two studies involving three distinct types of transient perturbations of the ionospheric convection pattern. Substorm Associated Radar Auroral Surges (SARAS) are examined in a statistical manner to obtain a more complete description of the feature. The results of this examination are utilised in a discussion of a possible magnetospheric source and generation mechanism for SARAS. The auroral radar signature of an o band is characterised with the aid of the complementary and coincident information provided by Viking UV images. Characterisation of the VHF radar signature resulting from the passage of this o band structure allows a link between a second o band and a radar flow burst signature to be made. It is suggested that a flow burst signature is observed coincident with the western (trailing edge) of the luminous region of an eastward drifting o band. A preliminary investigation of the field aligned current systems associated with the o band structure is also presented, the results of which compared favourably with models pertaining to the electrodynamics of an o band system.