Buildup of the ring current during periodic loading‐unloading cycles in the magnetotail driven by steady southward interplanetary magnetic field

Taktakishvili, A. L.; Кузнецова, М.; Hesse, Michael; Fok, M.‐C.; Rastätter, L.; Maddox, M.; Chulaki, A.; Gombosi, T. I.; Zeeuw, Darren L. De

doi:10.1029/2007ja012317

Cited by 12 publications

(16 citation statements)

References 22 publications

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“…The profile of magnetic perturbations we observe is also similar to the signatures found by Taktakishvili et al [2007]when using BATS‐R‐US to drive the FokRC model with similar solar wind conditions to these S IMF runs (though with an IMF B z of −15 nT). The oscillations seen in BATS‐R‐US were attributed to periodic reconnection events creating enhancements in the magnetic field that propagate inward from the tail.…”

Section: Discussionsupporting

confidence: 80%

Initial results from a dynamic coupled magnetosphere‐ionosphere‐ring current model

et al. 2012

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[1] In this paper we describe a coupled model of Earth's magnetosphere that consists of the Lyon-Fedder-Mobarry (LFM) global magnetohydrodynamics (MHD) simulation, the MIX ionosphere solver and the Rice Convection Model (RCM) and report some results using idealized inputs and model parameters. The algorithmic and physical components of the model are described, including the transfer of magnetic field information and plasma boundary conditions to the RCM and the return of ring current plasma properties to the LFM. Crucial aspects of the coupling include the restriction of RCM to regions where field-line averaged plasma-b ≤ 1, the use of a plasmasphere model, and the MIX ionosphere model. Compared to stand-alone MHD, the coupled model produces a substantial increase in ring current pressure and reduction of the magnetic field near the Earth. In the ionosphere, stronger region-1 and region-2 Birkeland currents are seen in the coupled model but with no significant change in the cross polar cap potential drop, while the region-2 currents shielded the low-latitude convection potential. In addition, oscillations in the magnetic field are produced at geosynchronous orbit with the coupled code. The diagnostics of entropy and mass content indicate that these oscillations are associated with low-entropy flow channels moving in from the tail and may be related to bursty bulk flows and bubbles seen in observations. As with most complex numerical models, there is the ongoing challenge of untangling numerical artifacts and physics, and we find that while there is still much room for improvement, the results presented here are encouraging.Citation: Pembroke, A., F. Toffoletto, S. Sazykin, M. Wiltberger, J. Lyon, V. Merkin, and P. Schmitt (2012), Initial results from a dynamic coupled magnetosphere-ionosphere-ring current model,

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Section: Discussionsupporting

confidence: 80%

Initial results from a dynamic coupled magnetosphere‐ionosphere‐ring current model

et al. 2012

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“…The pure‐MHD paper of Goodrich et al [2007] and the modified‐MHD paper of Kuznetsova et al [2007] do not present any detail about the inner magnetosphere. Taktakishvili et al [2007] does emphasize the inner magnetosphere, and the results do not seem to show any evidence of interchange instability there. It is not clear why there is such a difference between the predictions of the models.…”

Section: Simulation Results and Discussionmentioning

confidence: 65%

“… Kuznetsova et al [2007] modified the MHD Ohm's law in the regions of likely reconnection to include nongyrotropic pressures, which could reproduce quasi‐periodic reconnections when driven by a steady southward IMF. With this modification, Taktakishvili et al [2007] modeled the ring current buildup and the oscillation of energetic flux at geosynchronous orbit by coupling the BATS‐R‐US code and the Fok Ring Current Model, providing a detailed picture of inner‐magnetospheric particles, on the basis of MHD‐computed electric and magnetic fields.…”

Section: Introductionmentioning

confidence: 99%

Rice Convection Model simulation of the 18 April 2002 sawtooth event and evidence for interchange instability

et al. 2008

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[1] We present the results of a Rice Convection Model (RCM) simulation of the 18 April 2002 sawtooth event. This event occurred as a series of quasi-periodic substorms during fairly stable solar wind conditions. It is modeled by (1) prescribing a solar-wind-driven magnetic field model (T01_s) augmented by additional current loops representing the magnetic effects of the substorm current wedge and (2) by carefully specifying a substorm-phase-dependent plasma distribution at the RCM outer boundary at 8 R e such that a hot and attenuated plasma distribution is used after every substorm onset. The set of input parameters was adjusted to make the simulation results agree with the primary signatures of the sawtooth event, specifically the sequence of magnetic field stretching and dipolarization observed by the GOES spacecraft and the associated sharp increases and gradual decreases in the flux of energetic protons measured by the LANL/Synchronous Orbit Plasma Analyzer (SOPA) instruments on other geosynchronous spacecrafts. The results suggest the important role that higher temperature and lower density plasma-sheet plasma plays in producing flux enhancements at geosynchronous orbit. The results also confirm that induction electric fields associated with magnetic field collapse after substorm onsets can serve as a likely mechanism for the energization of particles up to 25 keV. Synthetic high-energy neutral atom images are compared with IMAGE/HENA measurements for 10-60 keV hydrogen atoms. Magnetic field dipolarization over a large range of local time resulted in a dramatic reduction in the plasma entropy parameter PV 5/3 on the boundary. The simulation indicates that the ring current intensified 10-20 minutes after every onset, associated with the injection of low PV 5/3 flux tubes through the boundary. The low PV 5/3 plasma also produced an interchange convection in the inner magnetosphere, which drives Birkeland currents in a quasi-periodic upward-downward pattern with a lifetime of 40-60 minutes and spatial extent of 1.5-2.0 hours. The results suggest that the spatial quasi-periodic and nearly north-south-aligned auroral arcs observed by an IMAGE/FUV WIC detector might be caused by interchange instability.

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“…It can be seen that with the CRCM model, the near-Earth plasma domain can be described in great detail (e.g. Sazykin et al, 2005;Taktakishvili et al, 2007) and that the high fluxes predicted by the model are consistent with the location of the high pressure values indicated by the observations. Other in situ/model comparisons of this type reveal clues to physical processes responsible for such high pressure values (e.g.…”

Section: Pressure Comparisonmentioning

confidence: 61%

A general Cluster data and global MHD simulation comparison

et al. 2008

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Abstract. Among the many challenges facing the space weather modelling community today, is the need for validation and verification methods of the numerical models available describing the complex nonlinear Sun-Earth system. Magnetohydrodynamic (MHD) models represent the latest numerical models of this environment and have the unique ability to span the enormous distances present in the magnetosphere, from several hundred kilometres to several thousand kilometres above the Earth's surface. This makes it especially difficult to develop verification and validation methods which posses the same range spans as the models. In this paper we present a first general large-scale comparison between four years (2001)(2002)(2003)(2004) worth of in situ Cluster plasma observations and the corresponding simulated predictions from the coupled Block-Adaptive-Tree-SolarwindRoe-Upwind-Scheme (BATS-R-US) MHD code. The comparison between the in situ measurements and the model predictions reveals that by systematically constraining the MHD model inflow boundary conditions a good correlation between the in situ observations and the modeled data can be found. These results have an implication for modelling studies addressing also smaller scale features of the magnetosphere. The global MHD simulation can therefore be used to place localised satellite and/or ground-based observations into a global context and fill the gaps left by measurements.

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Buildup of the ring current during periodic loading‐unloading cycles in the magnetotail driven by steady southward interplanetary magnetic field

Cited by 12 publications

References 22 publications

Initial results from a dynamic coupled magnetosphere‐ionosphere‐ring current model

Initial results from a dynamic coupled magnetosphere‐ionosphere‐ring current model

Rice Convection Model simulation of the 18 April 2002 sawtooth event and evidence for interchange instability

A general Cluster data and global MHD simulation comparison

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