This project will conduct a quantitative and systematic investigation of the processes controlling the inner magnetospheric magnetic topology during geomagnetic storms. Selected storm events will be simulated with several numerical models and the results will be compared with each other and with observations. The data and model comparisons will make it possible to estimate the storm-time distortion of the magnetic field in the inner magnetosphere and to determine what current systems are responsible for which aspects of this distortion. The codes include the following: the Hot Electron and Ion Drift Integrator (HEIDI), the Inner Magnetosphere Particle Transport and Acceleration Model (IMPTAM), and the Space Weather Modeling Framework (SWMF, and the models coupled therein). This study will include extensive data analysis, particularly of magnetospheric magnetic field measurements and near-Earth plasma data (especially from Polar, Geotail, FAST, GOES and LANL geosynchronous satellites, and IMAGE), and ground-based magnetic perturbation observations. The primary objective of the study is to quantify which of the major current systems cause what aspects of the inner magnetospheric field distortion during storms. The project will examine specific storm events with physics-based numerical models to understand the flow of plasma leading to the current systems that dominate the magnetic field distortions. The relative contributions to the inner magnetosphere by convective or inductive electric fields will also be examined. The role of the plasma sheet density, temperature, and structure will be assessed to determine the influence of localized injections on the magnetic field distortions. The project involves an international collaboration and promoting underrepresented groups by bringing a woman scientist, Dr. Ganushkina of the Finnish Meteorological Institute, to Michigan to work directly with the Principal Investigator (PI).
Near-Earth space is where we most care about space weather because it is where we fly communication, navigation, and other satellites upon which we rely for everyday life. This region, however, undergoes dramatic changes during geomagnetic storms. Electrically charged particles are injected into near-Earth space and energized to levels that create a significant pressure and currents that can distort the local magnetic field. This grant focused on the relationship between charged particle dynamics, electric currents, and magnetic field distortions, especially during geomagnetic storm intervals. We analyzed several large data sets, superposing together observations from many storm intervals to understand the general flow of particles and the typical field distortions during different types of geomagnetic activity. We learned that there are clear and distinct differences between the two main solar wind driving conditions that typically cause geomagnetic storms, and that there are distinct differences between moderate and intense space storms. We also used state-of-the-art numerical models to investigate this relationship. We quantified the progression of current system formation and evolution during several magnetic storms. We interesting similarities between the models as well as defining differences that highlight the strengths and weaknesses of each model. The three uploaded images are color plots from some of our peer-reviewed articles published from this project. They show that the near-Earth nightside has a zoo of current systems, each with their own typical location and intensity and relationship to the charged particle pressure peak. While we found that the tail current could easily encroach within geosynchronous orbit during the main phase of magnetic storms, this current system retreated to well beyond geosynchronous orbit late in the main phase and during the recovery phase. The uploaded plots show that most of the current during intense magnetic storms is carried by the partial and/or symmetric ring current and not the tail current.
