GEM: The Role of Heavy Ion Outflow in Driving Sawtooth Oscillations

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The Geospace Environment Modeling (GEM) Program is a broad-based, community-initiated research program on the physics of the Earth's magnetosphere and the coupling of the magnetosphere to the atmosphere and to the solar wind. The work of GEM is accomplished in a series of campaigns and focus groups that solve specific problems leading to the construction of a global Geospace General Circulation Model (GGCM) with predictive capability. This project will contribute essential results to this goal pertaining to understanding a fundamental and mysterious mode of magnetic storms termed Sawtooth oscillations. Particularly, the project will investigate the potential role that heavy Oxygen ions escaping from the upper atmosphere may play in this. In addition, the project will support a graduate student participating in the research effort at University of New Hampshire. The specific goal of this investigation is to perform a superposed epoch analysis of ion outflow observed by the FAST spacecraft on the nightside during sawtooth events. The study will utilize a publicized database of 122 sawtooth events, comprising nearly 500 individual oscillations, which occurred during the FAST era (October 1996 to April 2009). About two thirds of these have coverage of the nightside aurora. This constitutes a sufficiently large set of events to allow for a comparison between the two main solar-wind drivers of Sawtooth events (SIR-driven and ICME-driven events, respectively) and to be able to compare these with the outflow from non-sawtooth events. Specifically, the superposed epoch analysis of the FAST data will be used to determine whether the observed outflow increases after each "tooth," driving the next tooth.