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The geospace plume, referring to the combined processes of the plasmaspheric and the ionospheric storm‐enhanced density (SED)/total electron content (TEC) plumes, is one of the unique features of geomagnetic storms. The apparent spatial overlap and joint temporal evolution between the plasmaspheric plume and the equatorial mapping of the SED/TEC plume indicate strong magnetospheric‐ionospheric coupling. However, a systematic modeling study of the factors contributing to geospace plume development has not yet been performed due to the lack of a sufficiently comprehensive model including all the relevant physical processes. In this paper, we present a numerical simulation of the geospace plume in the 31 March 2001 storm using the Multiscale Atmosphere‐Geospace Environment model. The simulation reproduces the observed linkage of the two plumes, which, we interpret as a result of both being driven by the electric field that maps between the magnetosphere and the ionosphere. The model predicts two velocity channels of sunward plasma drift at different latitudes in the dusk sector during the storm main phase, which are identified as the sub‐auroral polarization stream (subauroral polarization streams (SAPS)) and the convection return flow, respectively. The SAPS is responsible for the erosion of the plasmasphere plume and contributes to the ionospheric TEC depletion in the midlatitude trough region. We further find the spatial distributions of the magnetospheric ring current ions and electrons, determined by a delicate balance of the energy‐dependent gradient/curvature drifts and the E × B drifts, are crucial to sustain the SAPS electric field that shapes the geospace plume throughout the storm main phase. Key Points: The first whole geospace simulation to demonstrate coherent storm‐time evolution of plasmaspheric and total electron content (TEC) plumesThe model demonstrates plasmasphere erosion and TEC depletion by the subauroral polarization streams (SAPS)SAPS is sustained by magnetospheric ion and electron distributions formed by a delicate balance of energy‐dependent and E × B drifts [ABSTRACT FROM AUTHOR]

The role of diffuse electron precipitation in the formation of subauroral polarization streams (SAPS) is investigated with the Multiscale Atmosphere‐Geospace Environment (MAGE) model. Diffuse precipitation is derived from the distribution of drifting electrons. SAPS manifest themselves as a separate mesoscale flow channel in the duskside ionosphere, which gradually merges with the primary auroral convection toward dayside as the equatorward auroral boundary approaches the poleward Region‐2 field‐aligned currents (FACs) boundary. SAPS expand to lower latitudes and toward the nightside during the main phase of a geomagnetic storm, associated with magnetotail earthward plasma flows building up the ring current and intensifying Region‐2 FACs and electron precipitation. SAPS shrink poleward and sunward as the interplanetary magnetic field turns northward. When diffuse precipitation is turned off in a controlled MAGE simulation, ring current and duskside Region‐2 FACs become weaker, but subauroral zonal ion drifts are still comparable to auroral convection. However, subauroral and auroral convection manifest as a single broad flow channel without showing any mesoscale structure. SAPS overlap with the downward Region‐2 FACs equatorward of diffuse precipitation, where poleward electric fields are strong due to a low conductance in the subauroral ionosphere. The Region‐2 FACs extend to latitudes lower than the diffuse precipitation because the ring current protons penetrate closer to the Earth than the electrons do. This study reproduces the key physics of SAPS formation and their evolution in the coupled magnetosphere‐ionosphere during a geomagnetic storm. Diffuse electron precipitation is demonstrated to play a critical role in determining SAPS location and structure. Plain Language Summary: Subauroral polarization streams (SAPS) are a mesoscale (∼100–500 km) plasma flow channel frequently observed in the duskside subauroral ionosphere. This study investigates how diffuse electron precipitation affects the location and structure of SAPS, using the newly developed, state‐of‐the‐art geospace model of Multiscale Atmosphere‐Geospace Environment (MAGE). The MAGE model has the capability to directly simulate diffuse precipitation using particle drift physics. MAGE numerical experiments show that SAPS exhibit as a separate flow channel when diffuse precipitation is included in the simulation, but subauroral and auroral convections become one broad channel when diffuse precipitation is turned off. SAPS are produced in the gap region between the low latitude boundaries of electron aurora and downward field‐aligned current (FAC) on the duskside, where the ionospheric conductance is low due to lack of ionization while downward region‐2 FAC closes through this low conductance region. Strong poleward electric fields are generated to drive large westward ion drifts in the SAPS channel. Tracing back to the magnetosphere, the gap between the inner boundaries is formed because the ring current protons, whose distribution primarily determines the downward FAC, penetrate deeper than the electrons. Thus diffuse aurora, with plasma sheet as the source population, occurs poleward of the lower boundary of the downward Region‐2 current. This study demonstrates the importance of including diffuse precipitation in coupled geospace models to understand the dynamics of SAPS. Key Points: A fully coupled geospace model captures the key physical mechanism and distinct spatial structure of subauroral polarization streamsThe separation of the flow channel from the main auroral convection is determined by diffuse electron precipitation boundaryThe evolution of the SAPS in the ionosphere and magnetosphere is reproduced by the simulation in accordance with observations [ABSTRACT FROM AUTHOR]

The pursuit of realistic simulation of the physics of plasma transport, ring current formation and storm‐triggered Earth magnetic and electric field is an ongoing challenge in magnetospheric physics. To this end, we have implemented a coupling of the Lyon‐Fedder‐Mobarry (LFM) global magnetohydrodynamic model with the Rice convection model‐equilibrium (RCM‐E) of the inner‐magnetosphere and plasma sheet. This one‐way coupling scheme allows continuous update of the RCM‐E boundary conditions from the plasma moments calculated by the LFM while preserving entropy conservation. This results in a model that has the high‐resolution self‐consistent description of the inner magnetosphere and includes the effects of time‐dependent outer‐magnetospheric electromagnetic fields and plasma configurations. In addition, driving the RCM‐E in this way resolves the issue of having a plasma‐β‐constrained region in the coupled model of LFM‐RCM and expands the RCM‐E simulation region farther out into plasma sheet where the storm‐time plasma transportation takes place. In the ionosphere, the RCM‐E replaces the ionospheric electric field model of LFM with the one used by the RCM. The electric potential produced, along with the realistic ionospheric precipitation patterns shows strong consistency with the transportation patterns in the plasma sheet featured with well‐resolved bubbles and bursty bulk flows. Results from the simulations of an idealized event will be presented and discussed. Plain Language Summary: Understanding the important phenomena in the inner magnetosphere such as plasma transport, ring current formation, storm‐triggered Earth electromagnetic field changes and related ionospheric signatures is of great importance to space weather research. We implement a new coupling scheme of two models: the Lyon‐Fedder‐Mobarry (LFM) global magnetohydrodynamic model that simulates the global evolution of the magnetosphere and the Rice convection model‐equilibrium (RCM‐E) which self‐consistently describes the dynamics in the inner magnetosphere. Compared with the coupled model of LFM‐RCM, this new coupling scheme expands the RCM simulation region significantly farther out into plasma sheet, so the trajectory and evolution of the plasma flows can be tracked. In addition, the built‐in potential solver of RCM‐E allows us to more accurately connect the plasma distribution to the ionospheric potential by the Birkeland currents. The resulting electric potential better resolves the ionospheric features that correspond to the flow patterns in the plasma sheet than that in LFM‐RCM. The simulated precipitation patterns on the polar cap resemble the aurora observations during the injection events. Key Points: Self‐consistent inner‐magnetosphere model is driven by inputs from the Lyon‐Fedder‐Mobarry global magnetohydrodynamic modelThe expanded inner magnetospheric modeling region captures high‐resolution bursty bulk flows in the plasma sheetRealistic bursty bulk flows induced aurora patterns are simulated [ABSTRACT FROM AUTHOR]

The Lyon-Fedder-Mobarry global magnetosphere-ionosphere coupled model LFM-MIX is used to study Sun-Earth interactions by simulating geomagnetic storms. This work focuses on relating the multifidelity output from LFM-MIX to field observations of ionospheric conductance. Given a set of input values and solar wind data, LFM-MIX numerically solves the magnetohydrodynamic equations and outputs a bivariate spatiotemporal field of ionospheric energy and flux. Of particular interest here are LFM-MIX input settings required to match corresponding output with field observations. To estimate these input settings, a multivariate spatiotemporal statistical LFM-MIX emulator is constructed. The statistical emulator leverages the multiple fidelities such that the less computationally demanding yet lower fidelity LFM-MIX is used to provide estimates of the higher fidelity output. The higher fidelity LFM-MIX output is then used for calibration by using additive and non-linear discrepancy functions. [ABSTRACT FROM AUTHOR]

Computer models enable scientists to investigate real-world phenomena in a virtual laboratory using computer experiments. Statistical calibration enables scientists to incorporate field data in this analysis. However, the practical application is hardly straightforward for data structures such as spatial-temporal fields, which are usually large or not well represented by a stationary process model. We present a computationally efficient approach to estimating the calibration parameters using a criterion that measures discrepancy between the computer model output and field data. One can then construct empirical distributions for the calibration parameters and propose new computer model trials using sequential design. The approach is relatively simple to implement using existing algorithms and is able to estimate calibration parameters for large and nonstationary data. Supplementary R code is available online. [ABSTRACT FROM AUTHOR]

Abstract: While it is widely known that coronal mass ejections and their related solar wind features are significant drivers of activity with geospace it is less known that corotating interaction regions (CIRs) and the high speed stream (HSS) periods that precede them are also drivers of activity within geospace. The most recent extended and weak solar minimum interval has brought renewed attention to the space weather impacts of CIR+HSS periods since the highly structured and relatively stable coronal hole features on the Sun resulted in numerous CIR+HSS periods. In this paper we examine two Carrington Rotations (CRs) using the Coupled Magnetosphere Ionosphere Thermosphere (CMIT) model. CR2060 lasted from August 14, 2007 to September 11, 2007 and contained three CIR+HSS periods. CR2068, also known as the Whole Heliosphere Interval (WHI), began on March 20, 2008 and lasted until April 16, 2008 and contained two CIR+HSS periods. For each CR simulations driven by both L1 solar wind observations from the OMNI data set and L1 conditions extracted from CORHEL heliospheric simulations were conducted. The heliospheric simulation results capture the velocity and density structures seen in the solar wind well for CR2060 and only get one of the CIR+HSS periods in CR2068. In each CR the heliospheric simulations produce a much weaker IMF and have less temporal variability in all parameters. We compare the results of the CMIT simulations for each CR to observations of the cross polar cap potential (CPCP), hemispheric power (HP), and index including the computation of RMS and cross correlation error metrics. We examine the response of the thermospheric density during these intervals by utilizing data from the CHAMP satellite. In the magnetosphere we use magnetic field data from the GOES spacecraft to asses the different simulations ability to describe the distribution and intensity the ULF wave power. Our results show that the L1 driven simulations under-estimates the index and HP and over-estimates the CPCP. We believe that over estimation of the CPCP is directly linked to the low HP highlighting the need for an improved precipitation model within CMIT. The ULF power in the L1 simulations compares well with the observations, especially for the compressional component important in radiation belt energization processes. In all cases, the CMIT simulations driven by the heliospheric simulation results produce dramatically inferior predictions highlighting the importance of having good IMF predictions in heliospheric model results and possibly indicating the importance of having fluctuations in the solar wind. [Copyright &y& Elsevier]

Abstract: A goal of predictive models of the space radiation environment is to provide advanced knowledge of significant variations in the highly energetic particle populations that form the Earth''s radiation belts. The global geomagnetic field models that result from the Center for Integrated Space-weather Modeling (CISM) effort will provide a necessary input, a real-time description of the dynamic variation of the electromagnetic fields in the magnetosphere, for conducting detailed simulations of the radiation belts. In this work, we describe the issues and techniques that CISM will use to provide a physical space radiation model. An analysis of the global field configurations typical of the magneto hydrodynamic (MHD) models used in CISM suggest that much of the radiation belt modeling can proceed under a guiding center particle approximation, whereby individual, non-interacting test particles are used to track the aggregate dynamics of the radiation belts. This technique provides a relatively simple means of both conducting the necessary simulations, and coupling the relevant codes with other elements of the CISM project. The guiding center equations used to track the particles are based on a phase-space conserving approximation that conserves energy in regions of high curvature. Examples of test particle simulations with the MHD fields are given, both in the initial trapped particle population, and among the energetic particles that form the plasma sheet in the tail. These simulations suggest that multiple radiation belt models running simultaneously in the framework provided by CISM can be combined to provide an overall picture of the energetic particle environment. Finally, analysis of the spectral properties of the fields suggests how an alternate approach to modeling the global radiation belts, solution of the appropriate transport equations, might be advanced through the CISM effort. [Copyright &y& Elsevier]

We examine the simulation of the January 10 1997, magnetic storm using the Lyon-Fedder-Mobarry three-dimensional magnetohydrodynamic simulation of the interaction of the solar wind with the magnetosphere. We explore the response of the energy coupling between the solar wind and the magnetosphere during the extreme solar wind conditions produced by magnetic cloud that hit the Earth's magnetosphere during the first half of January 10. During the early part of the event, the simulation produced substorm-like behavior marked by a loading and unloading of stored magnetic flux. However, during the period of strong, sustained solar wind energy Input, the loading-unloading behavior essentially goes away sd the simulation entered a directly driven phase. During this direct-driving phase the solar wind dynamic pressure controlled the ionospheric Joule heating in the simulation. [ABSTRACT FROM AUTHOR]

Abstract: This paper describes the 3D simulation of a space weather event using the coupled model approach adopted by the Center for Integrated Space Weather Modeling (CISM). The simulation employs corona, solar wind, and magnetosphere MHD models, and an upper atmosphere/ionosphere fluid dynamic model, with interfaces that exchange parameters specifying each component of the connected solar terrestrial system. A hypothetical coronal mass ejection is launched from the Sun by a process emulating photospheric field changes such as are observed with solar magnetographs. The associated ejected magnetic flux rope propagates into a realistically structured solar wind, producing a leading interplanetary shock, sheath, and magnetic cloud. These reach 1AU where the solar wind and interplanetary magnetic field parameters are used to drive the magnetosphere–ionosphere–thermosphere coupled model in the same manner as upstream in situ measurements. The simulated magnetosphere responds with a magnetic storm, producing enhanced convection and auroral energy inputs to the upper atmosphere/ionosphere. These results demonstrate the potential for future studies using a modular, systemic numerical modeling approach to space weather research and forecasting. [Copyright &y& Elsevier]