Characterization of GPS Total Electron Content Signatures during Sudden Magnetospheric Compression Events

Abstract:

Interplanetary (IP) shock events are categorized by their velocity and impact angle, defined as the angle between the shock normal vector and the Sun-Earth line. Previous work has shown that shocks with lower impact angles tend to be more geoeffective because a more frontal shock will compress the magnetosphere more uniformly and evenly than an oblique shock event. This study seeks to verify this result using total electron content (TEC) measurements. TEC data provides high time resolution global coverage, suitable for studying the detailed latitudinal and local time characteristics of the magnetosphere-ionosphere response to an IP shock event. In auroral regions, dayside TEC enhancements in response to an IP shock are generally associated with shock aurora while at lower latitudes they are thought to be caused by compression of the dayside magnetosphere. By choosing two IP shock events with similar solar wind velocities, yet different impact angles, we can examine the role impact angle plays in controlling the global evolution of TEC signatures. Furthermore, by using TEC in addition to more traditional datasets, such as in situ measurements and ground magnetometers, we can gain further valuable insights into how IP shocks perturb the Earth’s space environment. Preliminary results from case studies of two events with similar velocities, yet different impact angles suggest that lower shock impact angles do indeed cause a larger TEC response.