Date of Award:

5-2013

Document Type:

Dissertation

Degree Name:

Doctor of Philosophy (PhD)

Department:

Electrical and Computer Engineering

Committee Chair(s)

Edmund A. Spencer

Committee

Edmund A. Spencer

Committee

Robert Schunk

Committee

Charles M. Swenson

Committee

Reyhan Bakhtur

Committee

Jacob Gunther

Abstract

A geomagnetic storm is a disturbance in the earth's space environment in response to a disturbance in the solar wind. The earth's ring current that is a toroidal current flowing roughly in the region also occupied by the Van-Allen radiation belt is energized during a geomagnetic storm. This leads to a decrease in the horizontal component of the geomagnetic field on the earth's surface. The Disturbance Storm Time (Dst) index, which is a measure of the intensity of the ring current, is calculated by taking the average of this decrease in the horizontal intensity across four low latitude magnetometer stations and removing the quiet time secular variations. The rate of decrease of the Dst index is an indicator of the deenergization of the ring current particles. But there are several issues with the Dst measurement as a proxy of the ring current energy. In particular, the percentage contribution of the tail current effect to the Dst index is still debated. In this work, an effort has been made to separate and quantify the possible contribution of the tail current to the Dst index. The relative contribution for a selected set of storms for which the interplanetary magnetic field turned northward abruptly after the peak in Dst was observed is estimated.

The results indicate the contribution from the tail current to the Dst is important. In addition, the reduction of the cross-tail current during substorm dipolarization is predicted by the measured isotropic boundary locations. Several well known phenomena are identified in the magnetometer movie maps. The improved space weather prediction capability obtained as a result of this work helps in protecting our space based assets. The auroral precipitation that affects airline traffic on polar routes and ground-induced currents that affect long pipe lines and electricity grids can now be better understood and protected.

Checksum

2d6c885f9a5d3d32ab7d3d043b6b0f4c

Download

Share

COinS

Copyright for this work is retained by the student. If you have any questions regarding the inclusion of this work in the Digital Commons, please email us at .