Knowledge of the ion composition in the near-Earth's magnetosphere and plasma sheet is essential for the understanding of magnetospheric processes and instabilities. The presence of heavy ions of ionospheric origin in the magnetosphere, in particular oxygen (O + ), influences the plasma sheet bulk properties, current sheet (CS) thickness and its structure. It affects reconnection rates and the formation of Kelvin-Helmholtz instabilities. This has profound consequences for the global magnetospheric dynamics, including geomagnetic storms and substorm-like events. The formation and demise of the ring current and the radiation belts are also dependent on the presence of heavy ions. In this review we cover recent advances in observations and models of the circulation of heavy ions in the magne- tosphere, considering sources, transport, acceleration, bulk properties, and the influence on the magnetospheric dynamics. We identify important open questions and promising avenues for future research.

Space science deals with the bodies within the solar system and the interplanetary medium; the primary focus is on atmospheres and above-at Earth the short timescale variation in the the geomagnetic field, the Van Allen radiation belts and the deposition of energy into the upper atmosphere are key areas of investigation. SpacePy is a package for Python, targeted at the space sciences, that aims to make basic data analysis, modeling and visualization easier. It builds on the capabilities of the well-known NumPy and matplotlib packages. Publication quality output direct from analyses is emphasized. The SpacePy project seeks to promote accurate and open research standards by providing an open environment for code development. In the space physics community there has long been a significant reliance on proprietary languages that restrict free transfer of data and reproducibility of results. By providing a comprehensive library of widely-used analysis and visualization tools in a free, modern and intuitive language, we hope that this reliance will be diminished for non-commercial users. SpacePy includes implementations of widely used empirical models, statistical techniques used frequently in space science (e.g. superposed epoch analysis), and interfaces to advanced tools such as electron drift shell calculations for radiation belt studies. SpacePy also provides analysis and visualization tools for components of the Space Weather Modeling Framework including streamline tracing in vector fields. Further development is currently underway. External libraries, which include well-known magnetic field models, high-precision time conversions and coordinate transformations are accessed from Python using ctypes and f2py. The rest of the tools have been implemented directly in Python. The provision of open-source tools to perform common tasks will provide openness in the analysis methods employed in scientific studies and will give access to advanced tools to all space scientists, currently distribution is limited to non-commercial use.

[1] The temporal and spatial development of the ring current is evaluated during the 23-26 October 2002 high-speed stream (HSS) storm, using a kinetic ring current-atmosphere interactions model with self-consistent magnetic field (RAM-SCB). The effects of nondipolar magnetic field configuration are investigated on both ring current ion and electron dynamics. As the self-consistent magnetic field is depressed at large (>4R E ) radial distances on the nightside during the storm main phase, the particles' drift velocities increase, the ion and electron fluxes are reduced and the ring current is confined closer to Earth. In contrast to ions, the electron fluxes increase closer to Earth and the fractional electron energy reaches $20% near storm peak due to better electron trapping in a nondipolar magnetic field. The ring current contribution to Dst calculated using BiotSavart integration differs little from the DPS relation except during quiet time. RAM-SCB simulations underestimate |SYM-H| minimum by $25% but reproduce very well the storm recovery phase. Increased anisotropies develop in the ion and electron velocity distributions in a self-consistent magnetic field due to energy dependent drifts, losses, and dispersed injections. There is sufficient free energy to excite whistler mode chorus, electromagnetic ion cyclotron (EMIC), and magnetosonic waves in the equatorial magnetosphere. The linear growth rate of whistler mode chorus intensifies in the postmidnight to noon sector, EMIC waves are predominantly excited in the afternoon to midnight sector, and magnetosonic waves are excited over a broad MLT range both inside and outside the plasmasphere. The wave growth rates in a dipolar magnetic field have significantly smaller magnitude and spatial extent.Citation: Jordanova, V. K., D. T. Welling, S. G. Zaharia, L. Chen, and R. M. Thorne (2012), Modeling ring current ion and electron dynamics and plasma instabilities during a high-speed stream driven storm,

[1] The importance of ionospheric O + on the development of the storm time ring current is recognized but not well understood. The addition of this outflow in global MHD models has the potential to change the magnetic field configuration, particle densities and temperatures, and the convection electric field. This makes including heavy ion outflow in ring current simulations difficult, as this addition cannot be easily decoupled from a host of other changes. This study attempts to overcome this problem by using three coupled models, PWOM, RIM, and BATS-R-US, to drive a ring current model, RAM-SCB. The differences in drivers when outflow is included and is not included are compared to see how outflow changes ring current input. It is found that including this outflow reduces the convection electric field, lowers the plasma sheet number density and temperature, and increases the complexity of the plasma sheet ion composition both temporally and spatially. These changes cause an overall reduction in ring current energy density. Further simulations that attempt to isolate these effects find that the most important change in terms of ring current development is the drop in convection electric field. Local time dependencies of O + injections are found to be nontrivial as well. Capturing all of these effects requires a whole system, first-principles approach.

[1] It is shown that the banana current, a current system in the inner magnetosphere closing entirely within the magnetosphere (i.e., not through the ionosphere or on the magnetopause) but not circumflowing around the Earth, is a regular feature of near-Earth space. Closure options for the eastward asymmetric current on the inside of a localized pressure peak were explored, with the conclusion that the current must close via westward current around the outside of the high pressure region. It is a current that encircles a pressure peak and, therefore, whenever there is a pressure peak in the inner magnetosphere, a banana current exists. If multiple pressure peaks exist in the inner magnetosphere, then multiple banana currents will also coexist. Its occurrence rate is equal to that of the partial ring current, defined here as westward magnetospheric current that closes through field-aligned currents into and out of the ionosphere. Its magnitude can reach a few mega-amps during the main phase of storms, but drops to <0.1 MA during extended quiet intervals. The magnetic perturbation related to this current is strong within the region of high plasma pressure that it encircles, but is otherwise very weak outside of the banana current loop because the oppositely-directed current flow on either side of the loop largely cancels each other. In general, its related magnetic field is a few nanotesla of northward perturbation for both ground-based and geosynchronous magnetometers, making it difficult to magnetically detect. The banana current is placed in the context of the other near-Earth nightside current systems.