Sudden compression of the outer magnetosphere associated with an ionospheric mass ejection

Russell, C. T.; Zhou, X.; J., P.; Kawano, Hideaki; Moore, T. E.; Peterson, W. K.; Cladis, J. B.; Singer, H. J.

doi:10.1029/1999gl900455

Cited by 35 publications

(31 citation statements)

References 8 publications

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“…We instead propose another mechanism involving "preexisting" ions to explain the dynamic variation in the ionospheric outflow. The behavior of pre-existing outflow ions in the dynamics of the magnetosphere was mentioned qualitatively in previous studies [e.g., Russell et al, 1999;Peterson et al, 2009], but no supporting evidence has yet been provided.…”

Section: Introductionmentioning

confidence: 97%

“…However, using observations from the Polar spacecraft over the polar cap, Cladis et al [2000] showed an example where O + ions acquired their energies in a short time primarily through centrifugal acceleration in the shock event on 24 September 1998. During this event, which was also studied by Moore et al [1999], Russell et al [1999], and Strangeway et al [2000], the O + parallel velocity increased from 25 to 100 km/s in 2 min.…”

Section: Introductionmentioning

confidence: 99%

“…[30] Comparison of the shock-related outflow variation on 11 October 2001 in the tail lobe with that on 24 September 1998 in the polar cap Russell et al, 1999;Cladis et al, 2000;Strangeway et al, 2000] can provide us with a more accurate picture of ionospheric outflow in the global magnetosphere. Similar information as given in Figures 2, 5, and 7 was reported by Cladis et al [2000] for the polar cap event.…”

Section: Regional Differences In Shock-driven Outflow Variationsmentioning

confidence: 99%

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Shock-driven variation in ionospheric outflow during the 11 October 2001 moderate storm

et al. 2011

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[1] The Composition and Distribution Function (CODIF) Analyzer on board the Cluster spacecraft frequently observes narrow-energy, field-aligned O + ions over the polar caps and in the lobes, particularly during storm times. This population is due to ion outflow from the cusp. During the 11 October 2001 moderate storm, CODIF, located in the southern lobe at ∼12 Earth radii (R E ) down the tail and moving inbound, observed a change in the outflow. A sudden increase in solar wind dynamic pressure at 1702 UT led to a sudden increase in the energy of peak O + flux from ∼0.2 to 5 keV or an abrupt increase in parallel velocity from 54.0 ± 3.8 to 212.5 km/s. This high-energy population gradually decreased in energy over the next ∼2 h. The energy increase resulted from the effects of the solar wind shock on preexisting outflow. To model the effects of the shock, we first determined how the magnetic field configuration changed, by comparing the local magnetic field before and after the shock with the predictions of the T04s empirical model. The local field, reasonably well reproduced by T04s, experienced a 0.8-R E perpendicular displacement and a first 8.3°then 0.9°rotation in 3.8 min when the solar wind shock hit. We used local measurements of the H + drift velocity and magnetic field to calculate if the observed velocity increase was due to centrifugal acceleration. We found that at the beginning centrifugal acceleration contributed only 11.4%, i.e., 18.0 km/s, to the sudden O + parallel velocity increase; the net effect of the centrifugal acceleration is against the velocity increase. We conclude that the increase was actually due to the field displacement, which brought a higher velocity population to the Cluster location. A higher velocity is expected at higher latitudes due to the velocity filter effect that results from higher-energy ions moving further along the field line than lower-energy ions, as the field line convects over the polar cap and into the tail.

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Section: Introductionmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

Section: Regional Differences In Shock-driven Outflow Variationsmentioning

confidence: 99%

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Shock-driven variation in ionospheric outflow during the 11 October 2001 moderate storm

et al. 2011

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“…The compression scenario has some support in simulations (e.g., Shue et al, 1997) and observations (e.g. Russell et al, 1999;Wilken et al, 1982, and references therein). Despite the opposite correlation of convection and density, the number flux also shows a positive correlation with dynamic pressure.…”

Section: Solar Wind Density and Dynamic Pressurementioning

confidence: 99%

Plasma transport in the magnetotail lobes

et al. 2009

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Abstract. The Earth's magnetosphere is populated by particles originating from the solar wind and the terrestrial ionosphere. A substantial fraction of the plasma from these sources are convected through the magnetotail lobes. In this paper, we present a statistical study of convective plasma transport through the Earth's magnetotail lobes for various geomagnetic conditions. The results are based on a combination of density measurements from the Electric Field and Waves Experiment (EFW) and convection velocities from the Electron Drift Instrument (EDI) on board the Cluster spacecraft. The results show that variations in the plasma flow is primarily attributed to changes in the convection velocity, whereas the plasma density remains fairly constant and shows little correlation with geomagnetic activity. During disturbed conditions there is also an increased abundance of heavier ions, which combined with enhanced convection, cause an accentuation of the mass flow. The convective transport is much slower than the field aligned transport. A substantial amount of plasma therefore escape downtail without ever reaching the central plasma sheet.

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“…Figure 1 shows an example of a large magnetospheric compression that occurred on September 24, 1998. This event was examined in various studies (e.g., Moore et al, 1999;Russell et al, 1999;Strangeway et al, 2000) which in particular put forward a rapid response of the ionosphere with enhanced outflows of low-energy plasma. The top panel of Fig.…”

Section: Introductionmentioning

confidence: 99%

Energetic particle injections into the outer cusp during compression events

Delcourt¹,

Malova

Zelenyǐ

et al. 2005

Earth Planet Sp

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We investigate the dynamics of charged particles in the dayside magnetosphere in response to abrupt variations of the solar wind dynamical pressure. Using test particle simulations, we show that the electric field induced by the compression of the frontside magnetosphere may be responsible for prominent energization of plasma sheet ions as well as trapping at high latitudes. We demonstrate that, due to the short-lived character of the magnetic field line reconfiguration (on the time scale of a few minutes), the particle magnetic moment (first adiabatic invariant) may not be conserved during such events. Ions that are initially bouncing from one hemisphere to the other are found to experience nonadiabatic energization up to the hundred of keV range while being injected into the outer cusp. Such injections involve particles from limited portions of the dayside flux tubes. The energetic particles that are produced in the outer cusp during such events subsequently circulate about the field minimum at high latitudes without intercepting the equatorial plane, thus contributing to the high-energy populations that are observed in this region of space.

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Sudden compression of the outer magnetosphere associated with an ionospheric mass ejection

Cited by 35 publications

References 8 publications

Shock-driven variation in ionospheric outflow during the 11 October 2001 moderate storm

Shock-driven variation in ionospheric outflow during the 11 October 2001 moderate storm

Plasma transport in the magnetotail lobes

Energetic particle injections into the outer cusp during compression events

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