We present methods and algorithms that allow the Vlasiator code to run global, three-dimensional hybrid-Vlasov simulations of Earth's entire magnetosphere. The key ingredients that make Vlasov simulations at magnetospheric scales possible are the sparse velocity space implementation and spatial adaptive mesh refinement. We outline the algorithmic improvement of the semi-Lagrangian solver for six-dimensional phase space quantities, discuss the coupling of Vlasov and Maxwell equations' solvers in a refined mesh, and provide performance figures from simulation test runs that demonstrate the scalability of this simulation system to full magnetospheric runs.

The strongest event of geomagnetically induced currents (GIC) detected by the North‐West Russian GIC network occurred during the main phase of the magnetic storm on 28 and 29 June 2013. Extremely high value, 120 A, was recorded in the 330 kV transformers on Kola Peninsula in the 04–07 magnetic local time (MLT) sector. The Defense Meteorological Satellite Program (DMSP) spacecraft took a sequence of ultraviolet (UV) auroral images in the southern hemisphere and observed multiple omega bands. The ionospheric equivalent electric currents based on the International Monitor for Auroral Geomagnetic Effects (IMAGE) magnetometer network reveal a sequence of current vortex pairs moving eastward with the speed of 0.5–2.5 km/s that fits to the electrodynamics scheme of omega bands. Although the temporal variations of the associated current system are slow, the omega bands can be responsible for strong magnetic variations and GIC due to fast propagations of currents in the azimuthal direction.

Global magnetohydrodynamic (MHD) modeling is a powerful tool in space weather research and predictions. There are several advanced and still developing global MHD (GMHD) models that are publicly available via Community Coordinated Modeling Center's (CCMC) Run on Request system, which allows the users to simulate the magnetospheric response to different solar wind conditions including extraordinary events, like geomagnetic storms. Systematic validation of GMHD models against observations still continues to be a challenge, as well as comparative benchmarking of different models against each other. In this paper we describe and test a new approach in which (i) a set of critical large‐scale system parameters is explored/tested, which are produced by (ii) specially designed set of computer runs to simulate realistic statistical distributions of critical solar wind parameters and are compared to (iii) observation‐based empirical relationships for these parameters. Being tested in approximately similar conditions (similar inputs, comparable grid resolution, etc.), the four models publicly available at the CCMC predict rather well the absolute values and variations of those key parameters (magnetospheric size, magnetic field, and pressure) which are directly related to the large‐scale magnetospheric equilibrium in the outer magnetosphere, for which the MHD is supposed to be a valid approach. At the same time, the models have systematic differences in other parameters, being especially different in predicting the global convection rate, total field‐aligned current, and magnetic flux loading into the magnetotail after the north‐south interplanetary magnetic field turning. According to validation results, none of the models emerges as an absolute leader. The new approach suggested for the evaluation of the models performance against reality may be used by model users while planning their investigations, as well as by model developers and those interesting to quantitatively evaluate progress in magnetospheric modeling.

We compare predicted magnetopause positions at the subsolar point and four reference points in the terminator plane obtained from several empirical and numerical MHD models. Empirical models using various sets of magnetopause crossings and making different assumptions about the magnetopause shape predict significantly different magnetopause positions (with a scatter >1 R_E) even at the subsolar point. Axisymmetric magnetopause models cannot reproduce the cusp indentations or the changes related to the dipole tilt effect, and most of them predict the magnetopause closer to the Earth than nonaxisymmetric models for typical solar wind conditions and zero tilt angle. Predictions of two global nonaxisymmetric models do not match each other, and the models need additional verification. MHD models often predict the magnetopause closer to the Earth than the nonaxisymmetric empirical models, but the predictions of MHD simulations may need corrections for the ring current effect and decreases of the solar wind pressure that occur in the foreshock. Comparing MHD models in which the ring current magnetic field is taken into account with the empirical Lin et al. model, we find that the differences in the reference point positions predicted by these models are relatively small for B_z=0. Therefore, we assume that these predictions indicate the actual magnetopause position, but future investigations are still needed.

A new tomographic model (Vp, Vs, and Vp/Vs ratio) was built for two neighboring active volcanoes, Avacha and Koryaksky, which represent a serious hazard to the population and infrastructure of Petropavlovsk‐Kamchatsky, the main city of Kamchatka, Russia. Arrival times of seismic P and S waves from almost 5,000 local events, recorded by a permanent network of seismic stations during 2009–2018, were used for tomography. The resolution of the derived models was carefully tested by a series of synthetic simulations. Prominent anomalies with extremely high Vp/Vs ratios (up to 2.4) were retrieved directly beneath both volcanoes and interpreted as magma reservoirs containing high degrees of partial melt and/or fluids. Beneath Avacha, the upper limit of the anomaly is located at the depth of ~2 km below the surface. The reservoir appears to be connected to the surface by a neck‐shaped anomaly of high Vp/Vs ratio associated with active seismicity, which is interpreted as a magma and fluid conduit. Beneath Koryaksky, the magma related anomaly is deeper: Its upper limit is located at a depth of ~7 km below the surface. This anomaly is connected with the volcanic cone and is associated with a vertical seismicity cluster, which possibly marks the pathway of fluid ascent and degassing. Between the volcanoes, a 2‐ to 3‐km thick layer of very low Vp and Vs is interpreted as deposits of volcanoclastic sediments. Generally low Vp/Vs ratios in the area between the volcanoes show that the magma reservoirs in the upper crust are not interconnected.