One of the prominent effects of space weather is the variation of electric currents in the magnetosphere and ionosphere, which give rise to rapid geomagnetic field variations on the surface of the Earth. These Geomagnetic Disturbances (GMDs) can be highly localized and large amplitude. Because the causes of localized GMDs are unresolved, we seek to identify the physical drivers of these localized dB/dt spikes measured by ground magnetometers. We use the Space Weather Modeling Framework (SWMF) models to simulate the magnetosphere and reproduce these small-scale spikes. We use the operational Geospace configuration, which couples a global magnetohydrodynamic model to a height-integrated ionospheric electrodynamics solver and a kinetic ring current model. We run a series of simulations with increasingly higher spatial resolution to resolve small scale dB/dt dynamics. We quantify the success of the model against observation using Regional Station Difference (RSD), a metric calculated using dB/dt or geoelectric field to pinpoint when a single magnetometer station records a significantly different value than others within a given radius. We discuss future work to improve the model’s accuracy and our understanding of these small-scale structures.
We present latest results from the Conductance Model for Extreme Events (CMEE) and the Magnetosphere-Ionosphere-Thermosphere (MAGNIT) Conductance Model. Both models have been integrated into the Space Weather Modeling Framework (SWMF) to couple dynamically with the BATS-R-US MHD model, the Rice Convection Model (RCM) of the ring current & the Ridley Ionosphere Model (RIM) to simulate the April 2010 “Galaxy15” Event. The model is used with three grid configurations: the low-resolution configuration currently employed by NOAA’s Space Weather Prediction Center and two additional configurations that decrease the minimum grid resolution from ¼ RE to ⅛ and 1/16 RE. In addition, the simulation is driven with and without the dynamic coupling with RCM to study the impact of the ring current’s pressure correction in the inner magnetospheric domain. Using this model setup for a Maxwellian distribution, aforementioned precipitation sources are progressively applied and compared against the DMSP SSUSI observations. Finally, data-model comparisons against AMPERE Field-Aligned Currents, geomagnetic indices & magnetometer measurements are shown, with additional comparison against the existing conductance model in RIM. Results show remarkable progress in auroral precipitation modeling & MI coupling layouts in global models.
The fate of Plasmasphere material once it is drained out of the plasmasphere through a plume is unknown. One of two things may happen to the vented plasmasphere material. It can be either swept away with the solar wind, lost to the earth system, or it may be recirculated into the magnetosphere system, either through the low latitude boundary layer or over the poles and through the mantle. Recirculating plasmasphere material could plausibly enter the central plasma sheet and contribute to the ring current. Using observations to study the fate of the plasmasphere material is difficult as it is mostly hydrogen and becomes homogenized with solar wind hydrogen once it passes through the day side magnetopause. Numerical models, however, can keep the material distinct, opening the possibility of resolving the question using simulations. This work seeks to answer the question, does any plasmasphere material recirculate back into the magnetosphere? This is done by studying simulations produced by the Space Weather Modeling Framework (SWMF) configured to couple three models: the Block Adaptive Tree Solar Roe Up Wind Scheme (BATS-R-US) model, the Dynamic Global Core Plasma Model (DGCPM) plasmasphere model, and the Ridley Ionosphere Model (RIM). For this simulation BATS-R-US is configured to use two fluids. The first fluid represents currently accepted sources of ring current material, namely the solar wind and high latitude ionospheric outflow. The second fluid represents the plasmasphere. Within 10 Earth Radii (RE) the dynamics in BATS-R-US on closed field lines are dictated by coupling with the DGCPM. DGCPM passes the density of material in the plasmasphere to BATS-R-US. In addition to this coupling, RIM passes electric field information to both BATS-R-US and DGPCM while receiving current density form BATS-R-US. The outputs of the simulation are examined to evaluate plume recirculation. The fate of the plasmasphere material is then studied in an idealized.