Simulations of the magnetosphere for zero interplanetary magnetic field: The ground state

Sonnerup, B. U. Ö.; Siebert, K. D.; White, W. W.; Weimer, D. R.; Maynard, N. C.; Schoendorf, J.; Wilson, G. R.; Siscoe, G. L.; Erickson, G. M.

doi:10.1029/2001ja000124

Cited by 34 publications

(43 citation statements)

References 25 publications

(8 reference statements)

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“…This, along with the lack of antisunward convection in the center of the polar cap, is consistent with the dominance of hydrodynamic driven coupling during the previous half hour. The crosspolar-cap potential of 40 kV measured by DMSP exceeds the modeled value reported by Sonnerup et al [2001] for zero IMF and a solar wind density of 5 cm −3 , but below that for the zero IMF simulation with 40 cm −3 reported here. The longer that the system is under the influence of the magnetic hole associated with the HPS, the closer the magnetospheric system should approach the results produced in steady state simulations.…”

Section: Hydrodynamic and Magnetohydrodynamic Coupling To The Magnetocontrasting

confidence: 76%

“…Note that in the simulation of Figure 12a all equipotentials remain on closed magnetic flux, except for a small region well poleward of the terminator which maps to the magnetotail, consistent with LLBL driving of the convection pattern. The simulated density increase from 5 cm −3 (in the work by Sonnerup et al [2001]) to 40 cm −3 raised the cross-polarcap potential from 33 to 75 kV in these totally viscousdriven cases. Simulated increases of this sort suggest that density and dynamic pressure of the solar wind can drive high-latitude convection with cross-polar-cap potentials similar to those for moderate activity in merging driven cases.…”

Section: Hydrodynamic and Magnetohydrodynamic Coupling To The Magnetomentioning

confidence: 79%

“…The persistence of energetic electron precipitation over ∼3°magnetic latitude poleward of the convection reversal on both sides of the oval indicates that they resided on closed magnetic flux. Antisunward convection of closed flux is a condition that is only met in regions that map through the LLBL [e.g., Sonnerup, 1980;Sonnerup et al, 2001]. This, along with the lack of antisunward convection in the center of the polar cap, is consistent with the dominance of hydrodynamic driven coupling during the previous half hour.…”

Section: Hydrodynamic and Magnetohydrodynamic Coupling To The Magnetomentioning

confidence: 84%

“…The solar wind velocity was held constant at 400 km s −1 . [56] Conditions represented in Figure 12a may be compared with extensive simulations of the ground-state magnetosphere with "zero" IMF and a density of 5 cm −3 reported by Sonnerup et al [2001]. They found that closed field lines on the flanks of the magnetosphere stretched beyond X GSE = −100 R E , consistent with an effective "viscous interaction or mass diffusion" into the LLBL.…”

Section: Hydrodynamic and Magnetohydrodynamic Coupling To The Magnetomentioning

confidence: 91%

“…Magnetic merging between the IMF and the Earth's field completely turns off and coupling across the magnetopause is driven via diffusive processes, such as viscosity, resistivity, or flow shears associated with the KelvinHelmholtz instability. Sonnerup et al [2001] used the Inte-grated Space-weather prediction Model (ISM), a global MHD simulation code , to explore ground state properties including quantitative analysis of low-latitude boundary layer coupling to the ionosphere. They demonstrated that tailward flowing LLBL plasmas extend along the flanks of the magnetosphere with an interior, sunward return channel.…”

Section: Introductionmentioning

confidence: 99%

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Interactions of the heliospheric current and plasma sheets with the bow shock: Cluster and Polar observations in the magnetosheath

et al. 2011

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[1] On 12 March 2001, the Polar and Cluster spacecraft were at subsolar and cusp latitudes in the dayside magnetosheath, respectively, where they monitored the passage by Earth of a large-scale planar structure containing the high-density heliospheric plasma sheet (HPS) and the embedded current sheet. Over significant intervals, as the magnetic hole of the HPS passed Cluster and Polar, magnetic field strengths |B| were much smaller than expected for the shocked interplanetary magnetic field. For short periods, |B| even fell below values measured by ACE in the upstream solar wind. Within the magnetic hole the ratio of plasma thermal and magnetic pressures (plasma b) was consistently >100 and exceeded 1000. A temporary increase in lag times for identifiable features in B components to propagate from the location of ACE to those of Cluster and Polar was associated with the expansion (and subsequent compression) of the magnetic field and observed low |B|. Triangulation of the propagation velocity of these features across the four Cluster spacecraft configuration showed consistency with the measured component of ion velocity normal to the large-scale planar structure. B experienced large-amplitude wave activity, including fast magnetosonic waves. Within the low |B| region, guiding center behavior was disrupted and ions were subject to hydrodynamic rather than magnetohydrodynamic forcing. Under the reported conditions, a significant portion of the interplanetary coupling to the magnetosphere should proceed through interaction with the low-latitude boundary layer. Data acquired during a nearly simultaneous high-latitude pass of a Defense Meteorological Satellites Program satellite are consistent with this conjecture.

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Section: Hydrodynamic and Magnetohydrodynamic Coupling To The Magnetocontrasting

confidence: 76%

Section: Hydrodynamic and Magnetohydrodynamic Coupling To The Magnetomentioning

confidence: 79%

Section: Hydrodynamic and Magnetohydrodynamic Coupling To The Magnetomentioning

confidence: 84%

Section: Hydrodynamic and Magnetohydrodynamic Coupling To The Magnetomentioning

confidence: 91%

Section: Introductionmentioning

confidence: 99%

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Interactions of the heliospheric current and plasma sheets with the bow shock: Cluster and Polar observations in the magnetosheath

et al. 2011

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The magnetosphere under the radial interplanetary magnetic field: A numerical study

Tang

Wang

2013

JGR Space Physics

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[1] We investigate the magnetosphere under radial interplanetary magnetic fields (IMF) by using global magnetohydrodynamic simulations. The magnetosphere-ionosphere system falls into an unexpected state under this specific IMF orientation when the solar wind electric field vanishes. The most important features that characterize this state include (1) magnetic reconnections can still occur, which take place at the equatorward of the cusp in one hemisphere, the tailward of the cusp in the other hemisphere, and also in the plasma sheet; (2) significant north-south asymmetry exists in both magnetosphere and ionosphere; (3) the polar ionosphere mainly presents a weak two-cell convection pattern, with the polar cap potential valued at 30 kV; (4) the whole magnetosphere-ionosphere system stays in a very quiet state, and the AL index does not exceed -70 nT; and (5) the Kelvin-Helmholtz instability can still be excited at both flanks of the magnetosphere. These results imply the controlling role of the IMF direction between the solar wind and magnetosphere interactions and improve our understanding of the solar wind-magnetosphere-ionosphere system.

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Mercury's three‐dimensional asymmetric magnetopause

et al. 2015

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Mercury's magnetopause is unique in the solar system due to its relatively small size and its close proximity to the Sun. Based on 3 years of MErcury Surface, Space ENvironment, GEochemistry, and Ranging orbital Magnetometer and the Fast Imaging Plasma Spectrometer data, the mean magnetopause location was determined for a total of 5694 passes. We fit these magnetopause locations to a three‐dimensional nonaxially symmetric magnetopause which includes an indentation for the cusp region that has been successfully applied to the Earth. Our model predicts that Mercury's magnetopause is highly indented surrounding the cusp with central depth ~0.64 RM and large dayside extension. The dayside polar magnetopause dimension is, thus, smaller than the equatorial magnetopause dimension. Cross sections of the dayside magnetopause in planes perpendicular to the Mercury‐Sun line are prolate and elongated along the dawn‐dusk direction. In contrast, the magnetopause downstream of the terminator plane is larger in the north‐south than the east‐west directions by a ratio of 2.6 RM to 2.2 RM at a distance of 1.5 RM downstream of Mercury. Due to the northward offset of the internal dipole, the model predicts that solar wind has direct access to the surface of Mercury at middle magnetic latitudes in the southern hemisphere. During extremely high solar wind pressure conditions, the northern hemisphere middle magnetic latitudes may also be subject to direct solar wind impact.

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Simulations of the magnetosphere for zero interplanetary magnetic field: The ground state

Cited by 34 publications

References 25 publications

Interactions of the heliospheric current and plasma sheets with the bow shock: Cluster and Polar observations in the magnetosheath

Interactions of the heliospheric current and plasma sheets with the bow shock: Cluster and Polar observations in the magnetosheath

The magnetosphere under the radial interplanetary magnetic field: A numerical study

Mercury's three‐dimensional asymmetric magnetopause

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