3-D mesoscale MHD simulations of a cusp-like magnetic configuration: method and first results

Adamson, E.; Otto, A.; Nykyri, K.

doi:10.5194/angeo-29-759-2011

Cited by 19 publications

(22 citation statements)

References 41 publications

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“…These inner boundaries also exhibit significant fieldaligned flows. These flows as seen in the simulation results, though qualitatively consistent with observations (Lavraud et al, 2004bDunlop et al, 2005;Nykyri et al, 2011) are relatively small. It was previously noted that this appears to be the result of the low density asymmetry (between the magnetosphere and the magnetosheath) in this configuration.…”

Section: Discussionsupporting

confidence: 76%

“…A ballistic relaxation is then applied in order to produce a near-equilibrium configuration. For further details on the model and relaxation method see Adamson et al (2011).…”

Section: Methodsmentioning

confidence: 99%

“…In this paper, results are presented from a mesoscale cusplike magnetic field model (Adamson et al, 2011). The Earth's dipole tilt is neglected in the model.…”

Section: Introductionmentioning

confidence: 99%

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3-D mesoscale MHD simulations of magnetospheric cusp-like configurations: cusp diamagnetic cavities and boundary structure

2012

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Abstract. We present results from mesoscale simulations of the magnetospheric cusp region for both strongly northward and strongly southward interplanetary magnetic field (IMF). Simulation results indicate an extended region of depressed magnetic field and strongly enhanced plasma β which exhibits a strong dependence on IMF orientation. These structures correspond to the Cusp Diamagnetic Cavities (CDC's). The typical features of these CDC's are generally well reproduced by the simulation. The inner boundaries between the CDC and the magnetosphere are gradual transitions which form a clear funnel shape, regardless of IMF orientation. The outer CDC/magnetosheath boundary exhibits a clear indentation in both the x-z and y-z planes for southward IMF, while it is only indented in the x-z plane for northward, with a convex geometry in the y-z plane. The outer boundary represents an Alfvénic transition, mostly consistent with a slow-shock, indicating that reconnection plays an important role in structuring the high-altitude cusp region.

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Section: Discussionsupporting

confidence: 76%

“…A ballistic relaxation is then applied in order to produce a near-equilibrium configuration. For further details on the model and relaxation method see Adamson et al (2011).…”

Section: Methodsmentioning

confidence: 99%

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3-D mesoscale MHD simulations of magnetospheric cusp-like configurations: cusp diamagnetic cavities and boundary structure

2012

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“…For example, the modeling of cusp soft electron precipitation in a coupled global geospace simulation requires a self‐consistent, dynamic, and accurate specification of the cusp area [e.g., Zhang et al , ]. In global MHD simulations, the area of the polar cusp can be defined by either the spatial extent of the diamagnetic depression [e.g., Niehof et al , ; Adamson et al , ; Walsh et al , ] or the simulated cusp plasma property, viz, relative density enhancement or parallel ion flux at high altitude. The three diagnostic methods give approximately the same area of the polar cusp, and only the results from the diamagnetic depression method are shown in the following section.…”

Section: Resultsmentioning

confidence: 99%

Predicting the location of polar cusp in the Lyon‐Fedder‐Mobarry global magnetosphere simulation

et al. 2013

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[1] In this paper we compare observations of the high-latitude cusp from DMSP data to simulations conducted using the Lyon-Fedder-Mobarry (LFM) global magnetosphere simulation. The LFM simulation is run for the 31 August 2005 to 02 September 2005 moderate storm, from which the solar wind data exhibits a wide range of conditions that enable a statistical representation of the cusp to be obtained. The location of the cusp is identified using traditional magnetic depression and plasma density enhancement at high altitude. A new diagnostic using the parallel ion number flux is also tested for cusp identification. The correlation of the cusp latitude and various solar wind interplanetary magnetic field (IMF) coupling functions is explored using the three different cusp identification methods. The analysis shows (1) the three methods give approximately the same location and size of the simulated cusp at high altitude and (2) the variations of the simulated cusp are remarkably consistent with the observed statistical variations of the low-altitude cusp. In agreement with observations, a higher correlation is obtained using other solar wind coupling functions such as the Kan-Lee electric field. The magnetic local time (MLT) position of the simulated cusp is found to depend upon the IMF B y component, with a lower linear correlation. The width of the simulated cusp in both latitude and MLT is also examined. The size of the cusp is found to increase with the solar wind dynamic pressure with saturation seen when the dynamic pressure is greater than 3 nPa.

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“…The cusp magnetic field at high altitude is depressed and turbulent. This feature is often called a cusp diamagnetic cavity or “CDC” and is observed [e.g., Fritz et al , ; Walsh et al , ; Niehof et al , ] and modeled in the exterior cusp [ Adamson et al , ]. Although the diamagnetic cavity can show clear boundaries that delineate the cusp at large radial distances, it is not as clear at smaller radial distances.…”

Section: Observationsmentioning

confidence: 99%

Density variations in the Earth's magnetospheric cusps

et al. 2016

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Seven years of measurements from the Polar spacecraft are surveyed to monitor the variations of plasma density within the magnetospheric cusps. The spacecraft's orbital precession from 1998 through 2005 allows for coverage of both the northern and southern cusps from low altitude out to the magnetopause. In the mid‐ and high‐ altitude cusps, plasma density scales well with the solar wind density (ncusp/nsw∼0.8). This trend is fairly steady for radial distances greater then 4 RE. At low altitudes (r < 4RE) the density increases with decreasing altitude and even exceeds the solar wind density due to contributions from the ionosphere. The density of high charge state oxygen (O>+2) also displays a positive trend with solar wind density within the cusp. A multifluid simulation with the Block‐Adaptive‐Tree Solar Wind Roe‐Type Upwind Scheme MHD model was run to monitor the relative contributions of the ionosphere and solar wind plasma within the cusp. The simulation provides similar results to the statistical measurements from Polar and confirms the presence of ionospheric plasma at low altitudes.

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3-D mesoscale MHD simulations of a cusp-like magnetic configuration: method and first results

Cited by 19 publications

References 41 publications

3-D mesoscale MHD simulations of magnetospheric cusp-like configurations: cusp diamagnetic cavities and boundary structure

3-D mesoscale MHD simulations of magnetospheric cusp-like configurations: cusp diamagnetic cavities and boundary structure

Predicting the location of polar cusp in the Lyon‐Fedder‐Mobarry global magnetosphere simulation

Density variations in the Earth's magnetospheric cusps

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