Date of Award


Document Type

Thesis campus only



First Advisor

Niescja Turner

Second Advisor

Orrin Shindell

Third Advisor

Nirav Mehta


Coronal mass ejections (CMEs) and co-rotating interaction regions (CIRs) are two common types of solar wind disturbances that can drive geomagnetic storms and create space weather hazards. It is known that geoefficiency, or the efficiency of energy coupling, is one of the key differences between CMEs and CIRs. Further, the polar cap potential scales approximately linearly with the solar wind parameters in general but saturates under special conditions, including some geomagnetic storms. To look for the relationship between geoefficiency and polar cap saturation, I study the energies involved in 12 CME-driven geomagnetic storms and 10 CIR-driven geomagnetic storms from solar cycle 23. The coupling efficiencies are calculated from the solar wind input energy and the energy dissipated through ring current injection, ionospheric Joule heating, and auroral particle precipitation. The results are used to investigate the effect polar cap saturation may have on regulating energy coupling during geomagnetic storms.