Multiple coronal and heliospheric models have been recently upgraded at the Community Coordinated Modeling Center (CCMC), including the Wang-Sheeley-Arge (WSA)-Enlil model, MHD-Around-a-Sphere (MAS)-Enlil model, Space Weather Modeling Framework (SWMF), and heliospheric tomography using interplanetary scintillation data. To investigate the effects of photospheric magnetograms from different sources, different coronal models, and different model versions on the model performance, we run these models in 10 combinations. Choosing seven Carrington rotations in 2007 as the time window, we compare the modeling results with the Operating Mission as Nodes on the Internet data for near-Earth space environment during the late declining phase of solar cycle 23. Visual comparison is proved to be a necessary addition to the quantitative assessment of the models' capabilities in reproducing the time series and statistics of solar wind parameters. The MAS-Enlil model captures the time patterns of solar wind parameters better, while the WSA-Enlil model matches with the time series of normalized solar wind parameters better. Models generally overestimate slow wind temperature and underestimate fast wind temperature and magnetic field. Using improved algorithms, we have identified magnetic field sector boundaries (SBs) and slow-to-fast stream interaction regions (SIRs) as focused structures. The success rate of capturing them and the time offset vary largely with models. For this quiet period, the new version of MAS-Enlil model works best for SBs, while heliospheric tomography works best for SIRs. The new version of SWMF with more physics added needs more development. General strengths and weaknesses for each model are diagnosed to provide an unbiased reference to model developers and users. MotivationWe are motivated to validate the coronal and heliospheric models for the quasi-steady solar wind from the following three respects. First, a stream interaction region (SIR) forms when fast wind overtakes and interacts with the proceeding slow wind. It is in nature the same as the commonly known corotating interaction region [e.g., Smith and Wolfe, 1976;Gosling and Pizzo, 1999]. However, we use SIRs to emphasize that when the solar background changes within one Carrington rotation (CR), the resultant SIRs are short lived and do not corotate with the Sun to recur. In fact, Jian et al. [2006, 2011a] find 51% of SIRs near solar maximum and 10% at solar minimum do not recur at Earth. Large-amplitude Alfvén waves [Belcher and Davis, 1971] in SIRs and the following fast wind can drive a series of particle injections and affect the evolution of outer radiation belt (centered at about 4 R E ), as demonstrated in Miyoshi and Kataoka [2005]. Additionally, in geomagnetic storms, a large amount of energy is transferred from the solar wind into the magnetosphere and eventually dissipated in the thermosphere (about 90-600 km aboveground) and ionosphere (about 60-1000 km aboveground) by Joule heating and auroral precipitation [e.g., Gonzal...

Abstract. The ion dynamics in the distant Earth's magnetotail is studied in the case that a cross tail electric field E0 and reconnection-driven magnetic turbulence are present in the neutral sheet. The magnetic turbulence observed by the Geotail spacecraft is modeled numerically by a power law magnetic fluctuation spectrum. The magnetic fluctuations have the tearing mode parity with respect to the neutral sheet and are superimposed on a modified Harris sheet. A test particle simulation is performed for the ions, and the particle density, current density, bulk velocity, temperature, pressure, and heat flux are obtained for every point in the distant tail and as a function of the magnetic fluctuation level, 5B/Bo. It appears that the magnetic turbulence is very effective in maintaining the stationary structure of the current sheet and in changing the ion acceleration due to the electric field to thermal motion. Also, magnetic turbulence can inflate the current carrying region up to a thick current sheet, in contrast with the often assumed thin current sheet.

[1] The influence on ion motion of magnetic turbulence observed in the near-Earth magnetotail is investigated by numerical simulation. The magnetotail current sheet is modeled as a magnetic field reversal with a normal magnetic field component B n , plus a three-dimensional spectrum of magnetic fluctuations dB, which represents the observed magnetic turbulence. A cross tail electric field E y is included. A test particle simulation is performed assuming an anisotropic plasma source at the magnetospheric lobes, and using different values of B n and of the fluctuation level dB/B 0 . In the relevant range of parameters, B n and dB/B 0 have opposite effects on the current structure and on the ion heating. In particular, for a substantial level of fluctuations, dB/B 0^0 .2, the current splits into two sheets for B n $ 0, but increasing B n requires a higher dB/B 0 in order to have the current splitting. In addition, ion heating increases with the increase of dB/B 0 and with the decrease of B n , as these changes favor motion perpendicular to the average magnetic field and along the potential drop. When the magnetic fluctuations are small, the diamagnetic current wings and the magnetic field overshoots at the boundary of the current sheet are recovered for weakly anisotropic plasma distributions. Implications for the substorm growth phase and onset are discussed.

[1] In our efforts to bridge the gap between small-scale kinetic modeling and global simulations, we introduced an approach that allows to quantify the interaction between large-scale global magnetospheric dynamics and microphysical processes in diffusion regions near reconnection sites. We use the global MHD code BATS-R-US and replace an ad hoc anomalous resistivity often employed by global MHD models with a physically motivated dissipation model. The primary kinetic mechanism controlling the dissipation in the diffusion region in the vicinity of the reconnection site is incorporated into the MHD description in terms of nongyrotropic corrections to the induction equation. We developed an algorithm to search for reconnection sites in north-south symmetric magnetotail. Spatial scales of the diffusion region and magnitude of the reconnection electric field are calculated consistently using local MHD plasma and field parameters. The locations of the reconnection sites are constantly updated during the simulations. To clarify the role of nongyrotropic effects in the diffusion region on the global magnetospheric dynamics, we perform simulations with steady southward interplanetary magnetic field driving of the magnetosphere. Ideal MHD simulations with magnetic reconnection supported by numerical resistivity often produce quasi-steady configuration with almost stationary near-Earth neutral line (NENL). Simulations with nongyrotropic corrections demonstrate dynamic quasi-periodic response to the steady driving conditions. Fast magnetotail reconnection supported by nongyrotropic effects results in tailward retreat of the reconnection site with average speed of the order of 100 km/s followed by a formation of a new NENL in the near-Earth thin current sheet. This approach allowed to model for the first time loading/unloading cycle frequently observed during extended periods of steady low-mach-number solar wind with southward interplanetary magnetic field.

The paper deals with the unified model of particle acceleration (both electrons and protons) in the planetary magnetotaft due to explosive spontaneous reconnection. It is shown that the inductive electric field is able to generate energetic particle bursts. The proposed mechanism accelerates both species up to MeV energies in the Earth's magnetosphere (but with the electron flux much lower than the proton flux) and vice versa (practically only electrons) in the case of the compact magnetosphere of Mercury. The theory conforms with the experimental data obtained thus far in the terrestrial and Hermean magnetotails. Ambrosiano et al. [1988] the authors have made the numerical simulation at the particle acceleration in the course of the turbulent resistive MHD reconnection. Recently, in the papers by Eraker and Simpson [1986] and magnetosphere usually is accomplished by separate "quanta" of Baker et al. [1985], observations of energetic particle bursts in the magnetosphere of Mercury have been reported. The spacecraft Mariner 10 registered accelerated electron bursts with

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[1] During prolonged intervals of negative interplanetary magnetic field (IMF) B z the magnetosphere often enters a state in which quasi-periodic, large-amplitude oscillations of energetic particle fluxes are observed at the geosynchronous orbit. We use the global magnetosphere MHD code BATS-R-US output during a long period of steady southward IMF B z to drive the Fok Ring Current Model. Previous simulations of such events demonstrated flat behavior of the energetic particle fluxes after the initial injection. Periodical north/south IMF turning was required to reproduce oscillations in particle fluxes at geosynchronous orbit. In the present study we use a global magnetosphere MHD code that reproduces fast magnetotail reconnection rates observed in kinetic simulations. This results in periodical loading-unloading cycles in the magnetotail even for steady southward B z and can explain quasi-periodic oscillations of geosynchronous energetic particle fluxes. The total proton energy within geosynchronous orbit exhibits overall growth in time due to quasi-steady convection and oscillates due to injection through inductive electric field caused by multiple dipolarization. The flux oscillation amplitude is stronger in the outer regions of the ring current although the regions close to the geosynchronous orbit experience substantial perturbations as well.

In this paper, a novel approach that uses remote solar observations to forecast geomagnetically induced currents (GIC) is introduced. The approach utilizes first‐principles‐based propagation of the observed coronal mass ejections in the heliosphere and uses the modeled transient properties at the Earth to make site‐specific statistical estimates of GIC. The approach provides unprecedented forecast lead time of 1–2 days. The approach is validated for two nodes of the North American power transmission system by means of 14 coronal mass ejection events for which GIC observations are available. It is shown that the mean of the absolute value of the error in the GIC event start time prediction is about 5 h while the length of the events is underestimated on average by 17 h. The success rate, i.e., hits versus the total number of events, of the predictions are 12/14 and 7/14 for the two GIC stations, respectively. The implications of the new approach and the accuracy of the approach are discussed and possible avenues for future improvements are outlined.