Formation of dayside low‐latitude boundary layer under northward interplanetary magnetic field

Lin, Y.; Wang, X. Y.

doi:10.1029/2006gl027736

Cited by 11 publications

(15 citation statements)

References 18 publications

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“…In a recent study (Lin and Wang, 2006) showed that under a purely northward interplanetary magnetic field (IMF), magnetic reconnection in both northward and Southern Hemispheres leads to a continued formation of newly closed field lines on the dayside, a feature that we observe in our simulation (see Fig. 4a and 5).…”

Section: Impact Of Solar Wind Depression On Large Scale Structures: Tsupporting

confidence: 71%

“…Note that new particles injected from the solar wind on lateral surfaces have a half-space Maxwellian distribution velocity. The boundary conditions for the fields assume no reflection on the box edges as proposed by Lindman (1975). Charge conservation is fulfilled using charge and current deposition scheme as proposed by Villasenor and Buneman (1992).…”

Section: Code Description: Initial Conditionsmentioning

confidence: 99%

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Impact of solar wind depression on the dayside magnetosphere under northward interplanetary magnetic field

Baraka

Ben‐Jaffel

2011

Ann. Geophys.

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Abstract. We present a follow up study of the sensitivity of the Earth's magnetosphere to solar wind activity using a particles-in-cell model (Baraka and Ben Jaffel, 2007), but here during northward Interplanetary Magnetic Field (IMF). The formation of the magnetospheric cavity and its elongation around the planet is obtained with the classical structure of a magnetosphere with parallel lobes. An impulsive disturbance is then applied to the system by changing the bulk velocity of the solar wind to simulate a decrease in the solar wind dynamic pressure followed by its recovery. In response to the imposed drop in the solar wind velocity, a gap (abrupt depression) in the incoming solar wind plasma appears moving toward the Earth. The gap's size is a ∼15 R E and is comparable to the sizes previously obtained for both B z < 0 and B z = 0. During the initial phase of the disturbance along the x-axis, the dayside magnetopause (MP) expands slower than the previous cases of IMF orientations as a result of the abrupt depression. The size of the MP expands nonlinearly due to strengthening of its outer boundary by the northward IMF. Also, during the initial 100 t, the MP shrank down from 13.3 R E to ∼9.2 R E before it started expanding, a phenomenon that was also observed for southern IMF conditions but not during the no IMF case. As soon as they felt the solar wind depression, cusps widened at high altitude while dragged in an upright position. For the field's topology, the reconnection between magnetospheric and magnetosheath fields is clearly observed in both the northward and southward cusps areas. Also, the tail region in the northward Correspondence to: S. Baraka (suleiman.baraka@gmail.com) IMF condition is more confined, in contrast to the fishtailshape obtained in the southward IMF case. An X-point is formed in the tail at ∼110 R E compared to ∼103 R E and ∼80 R E for B z = 0 and B z < 0, respectively. Our findings are consistent with existing reports from many space observatories (Cluster, Geotail, Themis, etc.) for which predictions are proposed to test furthermore our simulation technique.

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Section: Impact Of Solar Wind Depression On Large Scale Structures: Tsupporting

confidence: 71%

Section: Code Description: Initial Conditionsmentioning

confidence: 99%

Impact of solar wind depression on the dayside magnetosphere under northward interplanetary magnetic field

Baraka

Ben‐Jaffel

2011

Ann. Geophys.

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“…It has been demonstrated that hybrid simulation is a powerful tool to solve physical problems in a system dominated by ion dynamics at a timescale ω ∼ Ω i and spatial scale kρ i ∼ 1, where ω is the wave frequency, k is the wave number, and Ω i and ρ i are the ion gyrofrequency and Larmor radius, respectively. Our 3‐D global‐scale hybrid code [ Lin and Wang , 2005, 2006] has been developed following the hybrid scheme of Swift [1996], and has been used to investigate ion dynamics and electromagnetic waves excited at the bow shock and cusp self‐consistently. In our model, protons are treated as fully kinetic particles and electrons are treated as a massless fluid, assuming quasi‐charge neutrality.…”

Section: Simulation Modelmentioning

confidence: 99%

Hybrid simulation of foreshock waves and ion spectra and their linkage to cusp energetic ions

2009

Self Cite

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[1] A three-dimensional global hybrid simulation is carried out to investigate energetic ions and electromagnetic waves in the quasi-parallel (Q-k) bow shock and cusp for a typical interplanetary magnetic field configuration during the cusp energetic particle events. The bow shock, magnetosheath, and dayside magnetosphere form by interaction between the solar wind and geomagnetic dipole field. Ions of solar wind characteristics injected into the system evolve along with electromagnetic waves in a self-consistent manner. Several important features are yielded from the simulation. Solar wind ions are accelerated by the waves and turbulence at the bow shock and foreshock as indicated by the ion distribution. The shock-accelerated ions possess an exponential energy spectrum with their differential flux scaled by the field-aligned distance to the bow shock, consistent with satellite observations. Second, the compressive and transversal waves in the foreshock are strongly correlated with the diffuse ion dynamics. Third, energetic ions in the magnetosheath and cusp downstream from the Q-k shock also exhibit a spectrum similar to those at the shock. By tracing trajectories of cusp energetic ions in the simulation, the origin of these ions is revealed. Their source is predominantly associated with the Fermi acceleration at the Q-k shock and foreshock. Waves in the magnetosheath and cusp, as well as magnetic reconnection at the high-latitude magnetopause, are relatively insignificant in accelerating cusp energetic particles.

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“…The inner boundary layer is composed of newly closed field lines that are formed from magnetosheath field lines by double magnetic reconnection, first poleward of one cusp and later poleward of the other cusp. In a 3‐D hybrid simulation, Lin and Wang [2006] showed that as a result of the double high‐latitude reconnection process, a thick magnetopause boundary layer is formed by the magnetosheath ions captured on the newly closed field lines and the transmitted magnetosheath ions near the high‐latitude X lines.…”

Section: Introductionmentioning

confidence: 99%

Solar wind plasma entry into the magnetosphere under northward IMF conditions

Raeder

Thomsen

et al. 2008

J. Geophys. Res.

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[1] This study examines how solar wind plasma enters the magnetosphere under northward interplanetary magnetic field (IMF) conditions, using the Open Geospace General Circulation Model (OpenGGCM) for various solar wind, IMF, and geomagnetic dipole conditions. We trace flow paths of individual fluid elements from the solar wind and study the variation of the topology of the magnetic field line along those flow paths. We find that there is an entry window through which the solar wind plasma can enter the magnetosphere as a result of double high-latitude reconnection under northward IMF conditions. We investigate how the entry window depends on solar wind, IMF, and geomagnetic dipole parameters, and we estimate the solar wind plasma entry rate for various conditions. We find that the effective entry rate under northward IMF conditions is of the order of 10 26 to 10 27 particles per second. We also estimate the conditions for which solar wind plasma entry is most efficient. The newly created flux tubes with closedfield topology are subsequently convected to the nightside and consequently cause magnetosheath plasma to be captured and enter the magnetosphere. Some captured dayside plasma takes about 90 min to convect along the magnetopause to a near tail flank region of the central plasma sheet, thus forming a cold dense plasma sheet. Double highlatitude reconnection can also release the captured plasma. Thus a balance of inflow and outflow of the captured plasma is eventually established under prolonged northward IMF conditions. We find that high-latitude reconnection is common under northward IMF conditions in our simulations. It occurs for IMF with any clock angle within [À90°, 90°], measured in front of the bow shock, and for any geomagnetic dipole tilt angle within [À30°, 30°]. An IMF field line with a zero x component usually first reconnects with a geomagnetic field line at the northern high-latitude boundary when the geomagnetic dipole tilts positive toward the Sun, and vice versa for negative dipole tilt. Our simulations also show that ionosphere conductance affects the convection of the newly closed field lines. Consequently, ionosphere conductance can change the solar wind plasma effective entry rate and can cause asymmetric effective entry rate with respect to positive and negative IMF clock angles.

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Formation of dayside low‐latitude boundary layer under northward interplanetary magnetic field

Cited by 11 publications

References 18 publications

Impact of solar wind depression on the dayside magnetosphere under northward interplanetary magnetic field

Impact of solar wind depression on the dayside magnetosphere under northward interplanetary magnetic field

Hybrid simulation of foreshock waves and ion spectra and their linkage to cusp energetic ions

Solar wind plasma entry into the magnetosphere under northward IMF conditions

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