Simulation studies of the Earth's radiation belts and ring current are very useful in understanding the acceleration, transport, and loss of energetic particles. Recently, the Comprehensive Ring Current Model (CRCM) and the Radiation Belt Environment (RBE) model were merged to form a Comprehensive Inner Magnetosphere-Ionosphere (CIMI) model. CIMI solves for many essential quantities in the inner magnetosphere, including ion and electron distributions in the ring current and radiation belts, plasmaspheric density, Region 2 currents, convection potential, and precipitation in the ionosphere. It incorporates whistler mode chorus and hiss wave diffusion of energetic electrons in energy, pitch angle, and cross terms. CIMI thus represents a comprehensive model that considers the effects of the ring current and plasmasphere on the radiation belts. We have performed a CIMI simulation for the storm on 5-9 April 2010 and then compared our results with data from the Two Wide-angle Imaging Neutral-atom Spectrometers and Akebono satellites. We identify the dominant energization and loss processes for the ring current and radiation belts. We find that the interactions with the whistler mode chorus waves are the main cause of the flux increase of MeV electrons during the recovery phase of this particular storm. When a self-consistent electric field from the CRCM is used, the enhancement of MeV electrons is higher than when an empirical convection model is applied. We also demonstrate how CIMI can be a powerful tool for analyzing and interpreting data from the new Van Allen Probes mission.

[1] We present full-particle simulations of 2-D magnetotail current sheet equilibria with open boundaries and zero driving. The simulations show that spontaneous formation of dipolarization fronts and subsequent formation of magnetic islands are possible in equilibria with an accumulation of magnetic flux at the tailward end of a sufficiently thin current sheet. These results confirm recent findings in the linear stability of the ion tearing mode, including the predicted dependence of the tail current sheet stability on the amount of accumulated magnetic flux expressed in terms of the specific destabilization parameter. The initial phase of reconnection onset associated with the front formation represents a process of slippage of magnetic field lines with frozen-in electrons relative to the ion plasma species. This non-MHD process characterized by different motions of ion and electron species generates a substantial charge separation electric field normal to the front. Citation: Sitnov, M. I., N. Buzulukova, M. Swisdak, V. G. Merkin, and T. E. Moore (2013), Spontaneous formation of dipolarization fronts and reconnection onset in the magnetotail,

A key process in the interaction of magnetospheres with the solar wind is the explosive release of energy stored in the magnetotail. Based on observational evidence, magnetic reconnection is widely believed to be responsible. However, the very possibility of spontaneous reconnection in collisionless magnetotail plasmas has been questioned in kinetic theory for more than three decades. In addition, in situ observations by multispacecraft missions (e.g., THEMIS) reveal the development of buoyancy and flapping motions coexisting with reconnection. Never before have kinetic simulations reproduced all three primary modes in realistic 2‐D configurations with a finite normal magnetic field. Moreover, 3‐D simulations with closed boundaries suggest that the tail activity is dominated by buoyancy‐driven instabilities, whereas reconnection is a secondary effect strongly localized in the dawn‐dusk direction. In this paper, we use massively parallel 3‐D fully kinetic simulations with open boundaries to show that sufficiently far from the planet explosive processes in the tail are dominated by reconnection motions. These motions occur in the form of spontaneously generated dipolarization fronts accompanied by changes in magnetic topology which extend in the dawn‐dusk direction over the size of the simulation box, suggesting that reconnection onset causes a macroscale reconfiguration of the real magnetotail. In our simulations, buoyancy and flapping motions significantly disturb the primary dipolarization front but neither destroy it nor change the near 2‐D picture of the front evolution critically. Consistent with recent multiprobe observations, dipolarization fronts are also found to be the main regions of energy conversion in the magnetotail.

[1] This study is the first to combine energetic neutral atom (ENA) observations from Two Wide-Angle Imaging Neutral-Atom Spectrometers (TWINS) and Interstellar Boundary Explorer (IBEX). Here we examine the arrival of an interplanetary shock and the subsequent geomagnetically effective substorm on 5 April 2010, which was associated with the Galaxy 15 communications satellite anomaly. IBEX shows sharply enhanced ENA emissions immediately upon compression of the dayside magnetosphere at 08:26:17+/À9 s UT. The compression drove a markedly different spectral shape for the dayside emissions, with a strong enhancement at energies >1 keV, which persisted for hours after the shock arrival, consistent with the higher solar wind speed, density, and dynamic pressure ($10 nPa) after the shock. TWINS ENA observations indicate a slower response of the ring current and precipitation of ring current ions as low-altitude emissions $15 min later, with the >50 keV ion precipitation leading the <10 keV precipitation by $20 min. These observations suggest internal magnetospheric processes are occurring after compression of the magnetosphere and before the ring current ions end up in the loss cone and precipitate into the ionosphere. We also compare MHD simulation results with both the TWINS and IBEX ENA observations; while the overall fluxes and distributions of emissions were generally similar, there were significant quantitative differences. Such differences emphasize the complexity of the magnetospheric system and importance of the global perspective for macroscopic magnetospheric studies. Finally, Appendix A documents important details of the TWINS data processing, including improved binning procedures, smoothing of images to a given level of statistical accuracy, and differential background subtraction.

[1] We present the coupling methodology and validation of a fully coupled inner and global magnetosphere code using the infrastructure provided by the Space Weather Modeling Framework (SWMF). In this model, the Comprehensive Ring Current Model (CRCM) represents the inner magnetosphere, while the Block-Adaptive-Tree Solar-Wind Roe-Type Upwind Scheme (BATS-R-US) represents the global magnetosphere. The combined model is a global magnetospheric code with a realistic ring current and consistent electric and magnetic fields. The computational performance of the model was improved to surpass real-time execution by the use of the Message Passing Interface (MPI) to parallelize the CRCM. Initial simulations under steady driving found that the coupled model resulted in a higher pressure in the inner magnetosphere and an inflated closed field-line region as compared to simulations without inner-magnetosphere coupling. Our validation effort was split into two studies. The first study examined the ability of the model to reproduce Dst for a range of events from the Geospace Environment Modeling (GEM) Dst Challenge. It also investigated the possibility of a baseline shift and compared two approaches to calculating Dst from the model. We found that the model did a reasonable job predicting Dst and Sym-H according to our two metrics of prediction efficiency and predicted yield. The second study focused on the specific case of the 22 July 2009 moderate geomagnetic storm. In this study, we directly compare model predictions and observations for Dst, THEMIS energy spectragrams, TWINS ENA images, and GOES 11 and 12 magnetometer data. The model did an adequate job reproducing trends in the data. Moreover, we found that composition can have a large effect on the result.

[1] The moderate storm of 22 July 2009 is the largest measured during the extended solar minimum between December 2006 and March 2010. We present observations of this storm made by the two wide-angle imaging neutral-atom spectrometers (TWINS) mission. The TWINS mission measures energetic neutral atoms (ENAs) using sensors mounted on two separate spacecrafts. Because the two spacecrafts' orbital planes are significantly offset, the pair provides a nearly optimal combination of continuous magnetospheric observations from at least one of the TWINS platforms with several hours of simultaneous, dual-platform viewing over each orbit. The ENA imaging study presented in this paper is the first reported magnetospheric storm for which both continuous coverage and stereoscopic imaging were available. Two populations of ENAs are observed during this storm. The first are emissions from the ring current and come from a parent population of trapped ions in the inner magnetosphere. The second, low-altitude emissions (LAEs), are the result of precipitating ions which undergo multiple charge exchange and stripping collisions with the oxygen exosphere. The temporal evolution of this storm shows that the LAEs begin earlier and are the brightest emissions seen during the main phase, while later, during the recovery, the LAE is only as bright as the bulk ring current emissions.

Impressive images from the Hubble Space Telescope not only help scientists understand our universe, but also enhance public interest in science, becoming a gateway for the youngest generation to enter Science, Technology, Engineering, and Mathematics (STEM) fields. Heliophysics observatories can also provide dramatic images of our space environment. The Solar and Heliospheric Observatory (SOHO; Domingo et al., 1995) images the dynamic activities of our Sun and its solar corona. Solar Terrestrial Relation Observatory (STEREO; Kaiser et al., 2008) monitors solar wind features propagating through interplanetary space. Imager for Magnetopause-to-Aurora Global Exploration (IMAGE; Burch, 2000) and Two Wide-Angle Imaging Neutral-Atom Spectrometers (TWINS; Goldstein & McComas, 2018) display the activities of the Earth's inner-magnetosphere in response to varying solar wind conditions. Time History of Events and Macroscale Interactions during Substorms (THEMIS) All Sky Imagers (ASI) distributed over the northern portions of North America (Mende et al., 2008) image aurora precipitation resulting from magnetospheric activities. The one missing image is the dayside magnetosphere, the starting point for the solar wind-magnetosphere interaction.

[1] We present simulation results from a one-way coupled global MHD model (Block-Adaptive-Tree Solar-Wind Roe-Type Upwind Scheme, BATS-R-US) and kinetic ring current models (Comprehensive Ring Current Model, CRCM, and Fok Ring Current, FokRC). The BATS-R-US provides the CRCM/FokRC with magnetic field information and plasma density/temperature at the polar CRCM/FokRC boundary. The CRCM uses an electric potential from the BATS-R-US ionospheric solver at the polar CRCM boundary in order to calculate the electric field pattern consistent with the CRCM pressure distribution. The FokRC electric field potential is taken from BATS-R-US ionospheric solver everywhere in the modeled region, and the effect of Region II currents is neglected. We show that for an idealized case with southward-northward-southward Bz IMF turning, CRCM-BATS-R-US reproduces well known features of inner magnetosphere electrodynamics: strong/weak convection under the southward/northward Bz; electric field shielding/overshielding/penetration effects; an injection during the substorm development; Subauroral Ion Drift or Polarization Jet (SAID/PJ) signature in the dusk sector. Furthermore, we find for the idealized case that SAID/PJ forms during the substorm growth phase, and that substorm injection has its own structure of field-aligned currents which resembles a substorm current wedge. For an actual event (12 August 2000 storm), we calculate ENA emissions and compare with Imager for Magnetopause-toAurora Global Exploration/High Energy Neutral Atom data. The CRCM-BATS-R-US reproduces both the global morphology of ring current and the fine structure of ring current injection. The FokRC-BATS-R-US shows the effect of a realistic description of Region II currents in ring current-MHD coupled models.Citation: Buzulukova, N., M.-C. Fok, A. Pulkkinen, M. Kuznetsova, T. E. Moore, A. Glocer, P. C. Brandt, G. Tóth, and L. Rastätter (2010), Dynamics of ring current and electric fields in the inner magnetosphere during disturbed periods: CRCM-BATS-R-US coupled model,