Interhemispheric Comparisons of Modeled Joule Heating During the 2013 and 2015 St. Patrick's Day Geomagnetic Storm

Geomagnetic storms can cause sudden changes in energy input from the magnetosphere, which can lead to extreme variability in the ionosphere-thermosphere system. This, in turn, can shorten the lifespan of satellite operations by increasing atmospheric drag and negatively affect modern technologies. It is crucial to improve our understanding and modeling of how the Earth's magnetosphere, ionosphere, and thermosphere interact during geomagnetic storms to protect our space- and ground-based infrastructure. The primary focus is on Joule heating, which is the most significant source of energy dissipation in the ionosphere-thermosphere system and can increase rapidly during geomagnetic storms. To investigate this, the University of Michigan Global Ionosphere-Thermosphere Model (GITM) is used to simulate the 2013 and 2015 St. Patrick's day geomagnetic storms with different electric field and auroral precipitation drivers. The study compares hemispheric variations in parameters, including Joule heating, neutral density, and electron density profiles obtained from GITM using an empirical versus a data-assimilative model. The study focuses on the potential causes of hemispheric Joule heating asymmetry, and the role of solar insolation in storm-time hemispheric energy input is explored. The study uses independent measures of total electron content and neutral density to compare data with models, and the consistency of these comparisons between the two simulations with different drivers is also discussed.