Some problems associated with the inversion of polar magnetic substorm data recorded at the earth's surface

The major thrust of this dissertation was to test an original method for resolving the current system associated with polar magnetic substorms from ground based magnetic observations. This method is based on a general technique of inversion review by Wiggins in 1972 and appears to give quite satisfactory results, at least, when the current system considered is simulated by a three-dimensional current system consisting of field-aligned currents flowing down to the ionosphere westward in the ionosphere, and back again to the magnetosphere. Before attempting the inversion of actual polar magnetic substorm data, the problems arising from the fact that the Earth is an electrical conductor which modifies the ground based magnetic signature of any external current system had to be investigated. This study was pursued on a very simple approximation to the substorm current system, that is, the purely ionospheric, infinite band of current. Its conclusions were later shown to remain valid for a three-dimensional source, at least, as long as the magnetic data were roughly recorded along the central meridian of the system

Some problems associated with the inversion of polar magnetic substorm data recorded at the earth's surface

The major thrust of this dissertation was to test an original method for resolving the current system associated with polar magnetic substorms from ground based magnetic observations. This method is based on a general technique of inversion review by Wiggins in 1972 and appears to give quite satisfactory results, at least, when the current system considered is simulated by a three-dimensional current system consisting of field-aligned currents flowing down to the ionosphere westward in the ionosphere, and back again to the magnetosphere. Before attempting the inversion of actual polar magnetic substorm data, the problems arising from the fact that the Earth is an electrical conductor which modifies the ground based magnetic signature of any external current system had to be investigated. This study was pursued on a very simple approximation to the substorm current system, that is, the purely ionospheric, infinite band of current. Its conclusions were later shown to remain valid for a three-dimensional source, at least, as long as the magnetic data were roughly recorded along the central meridian of the system