Connections between plasma sheet transport, Region 2 currents, and entropy changes associated with convection, steady magnetospheric convection periods, and substorms

2009 ◽  
Vol 114 (A9) ◽  
pp. n/a-n/a ◽  
Author(s):  
Larry R. Lyons ◽  
Chih-Ping Wang ◽  
Matina Gkioulidou ◽  
Shasha Zou
Keyword(s):  
Plasma Sheet ◽  
Magnetospheric Convection ◽  
Entropy Changes ◽  
Transport Region

scholarly journals IMF B y Influence on Magnetospheric Convection in Earth's Magnetotail Plasma Sheet

2019 ◽  
Vol 46 (21) ◽  
pp. 11698-11708 ◽  
Author(s):  
T. Pitkänen ◽  
A. Kullen ◽  
K. M. Laundal ◽  
P. Tenfjord ◽  
Q. Q. Shi ◽  
...  
Keyword(s):  
Plasma Sheet ◽  
Magnetospheric Convection

Effects of spatial diffusion in the inner plasma sheet and the structure of the diffusion tensor

1995 ◽  
Vol 13 (2) ◽  
pp. 111-117 ◽  
Author(s):  
V. E. Zakharov ◽  
M. I. Pudovkin
Keyword(s):  
Flux Tube ◽  
Plasma Sheet ◽  
Diffusion Tensor ◽  
Plasma Pressure ◽  
Spatial Diffusion ◽  
Angle Distribution ◽  
Inner Magnetosphere ◽  
Electron Population ◽  
Magnetospheric Convection ◽  
Isotropic Pitch

Abstract. A standard pair of equations is used to describe the behaviour of a single monoenergetic particle (proton or electron) population on a geomagnetic flux tube drifting in the magnetosphere. When particle losses from the drifting flux tube into the ionosphere are neglected, this behaviour is adiabatic in a thermodynamic sense. For a population of particles with an isotropic pitch-angle distribution, the generalization of that system of equations is obtained by adding radial and azimuthal spatial diffusion terms. The magnetic field is taken to be dipolar in the inner magnetosphere. The potential electric field is assumed to consist of magnetospheric convection and corotation components. Experimental data are used to estimate the radial equatorial profiles of the plasma sheet pressure. Assuming that the local time and L-shell variations are separable and supposing steady-state conditions, the expressions for the diffusion tensor components are evaluated. The influence of spatial diffusion on the radial and azimuthal profiles of the plasma pressure in the inner plasma sheet is also discussed.

scholarly journals Average characteristics of the midtail plasma sheet in different dynamic regimes of the magnetosphere

2004 ◽  
Vol 22 (6) ◽  
pp. 2107-2113 ◽  
Author(s):  
N. P. Dmitrieva ◽  
V. A. Sergeev ◽  
M. A. Shukhtina
Keyword(s):  
Magnetic Field ◽  
Magnetic Flux ◽  
Growth Phase ◽  
Plasma Sheet ◽  
Transfer Rate ◽  
Flux Transport ◽  
Data Set ◽  
Magnetospheric Convection ◽  
Flux Transfer ◽  
Night Flux

Abstract. We study average characteristics of plasma sheet convection in the middle tail during different magnetospheric states (Steady Magnetospheric Convection, SMC, and substorms) using simultaneous magnetotail (Geotail, 15-35 RE downtail) and solar wind (Wind spacecraft) observations during 3.5 years. (1) A large data set allowed us to obtain the average values of the plasma sheet magnetic flux transfer rate (Ey and directly compare it with the dayside transfer rate (Emod for different magnetospheric states. The results confirm the magnetic flux imbalance model suggested by Russell and McPherron (1973), namely: during SMC periods the day-to-night flux transport rate equals the global Earthward plasma sheet convection; during the substorm growth phase the plasma sheet convection is suppressed on the average by 40%, whereas during the substorm expansion phase it twice exceeds the day-to-night global flux transfer rate. (2) Different types of substorms were revealed. About 1/3 of all substorms considered displayed very weak growth in the tail lobe magnetic field before the onset. For these events the plasma sheet transport was found to be in a balance with the day-to-night flux transfer, as in the SMC events. However, the lobe magnetic field value in these cases was as large as that in the substorms with a classic growth phase just before the onset (both values exceed the average level of the lobe field during the SMC). Also, in both groups similar configurational changes (magnetic field stretching and plasma sheet thinning) were observed before the substorm onset. (3) Superimposed epoch analysis showed that the plasma sheet during the late substorm recovery phase has the characteristics similar to those found during SMC events, the SMC could be a natural magnetospheric state following the substorm.

scholarly journals Plasma sheet magnetic fields and flows during steady magnetospheric convection events

2013 ◽  
Vol 118 (10) ◽  
pp. 6136-6144 ◽  
Author(s):  
T. I. Pulkkinen ◽  
N. Partamies ◽  
J. Kissinger ◽  
R. L. McPherron ◽  
K.-H. Glassmeier ◽  
...  
Keyword(s):  
Magnetic Fields ◽  
Plasma Sheet ◽  
Magnetospheric Convection

scholarly journals Quasi-static MHD processes in Earth's magnetosphere

1988 ◽  
Vol 6 (3) ◽  
pp. 525-537 ◽  
Author(s):  
Gerd-Hannes Voigt
Keyword(s):  
Magnetic Field ◽  
Steady State ◽  
Plasma Sheet ◽  
Equilibrium Theory ◽  
Flux Tubes ◽  
Earth’S Magnetosphere ◽  
Magnetospheric Convection ◽  
Mhd Equilibrium ◽  
Earth's Magnetosphere ◽  
Flow Velocities

The purpose of this paper is to demonstrate how the MHD equilibrium theory can be used to describe the global magnetic field configuration of Earth's magnetosphere and its time evolution under the influence of magnetospheric convection. The MHD equilibrium theory represents magneto-hydrodynamics in the slow-flow approximation. In this approximation time scales are long compared to typical Alfvén wave travel times, and plasma flow velocities are small compared to the Alfvén speed. Under those conditions, the inertial term ρ(dv/dt) in the MHD equation of motion is a small second order term which can be neglected. The MHD equilibrium theory is not a static theory, though, because time derivatives and flow velocities remain first order quantities in the continuity equation, in the thermodynamic equation of state, and in the induction equation. Therefore one can compute slowly time-dependent processes, such as magnetospheric convection, in terms of series of static equilibrium states. However, those series are not arbitrary; they are constrained by thermodynamic conditions according to which the magnetosphere evolves in time.It is an interesting question, whether or not the magnetosphere, driven by slow, lossless, adiabatic, earthward convection of magnetotail flux tubes, can reach a steady state. There exist magnetospheric equilibria in which magnetotail flux tubes satisfy the steady-state condition d/dt (Pρ−γ) = 0. Those configurations exhibit a deep magnetic field minimum in the equatorial plane, near the inner edge of the tail plasma sheet. The magnetosphere becomes tearing-mode unstable in the neighborhood of such a minimum, thus leading to periodic onsets of substorms in the inner plasma sheet. This explains why distinct magnetic field minima have not been observed in this region. Magnetic substorms seem to be an inevitable element of the global convection cycle which inhibit the establishment of an ultimate steady state.MHD equilibria discussed in this paper result from linear and non-linear solutions to the two-dimensional Grad-Shafranov equation for isotropic thermal plasma pressure.

Average patterns of precipitation and plasma flow in the plasma sheet flux tubes during steady magnetospheric convection

1990 ◽  
Vol 38 (3) ◽  
pp. 355-363 ◽  
Author(s):  
V.A. Sergeev ◽  
W. Lennartsson ◽  
R. Pellinen ◽  
M. Vallinkoski ◽  
N.I. Fedorova
Keyword(s):  
Plasma Flow ◽  
Plasma Sheet ◽  
Flux Tubes ◽  
Magnetospheric Convection

scholarly journals Superposed epoch analysis of dense plasma access to geosynchronous orbit

2005 ◽  
Vol 23 (7) ◽  
pp. 2519-2529 ◽  
Author(s):  
B. Lavraud ◽  
M. H. Denton ◽  
M. F. Thomsen ◽  
J. E. Borovsky ◽  
R. H. W. Friedel
Keyword(s):  
Plasma Sheet ◽  
Ring Current ◽  
Dense Plasma ◽  
Transport Processes ◽  
Geosynchronous Orbit ◽  
Plasma Convection ◽  
Tail Region ◽  
Superposed Epoch Analysis ◽  
Magnetospheric Convection ◽  
Epoch Analysis

Abstract. We report on the occurrence of dense plasma access to geosynchronous orbit. We performed a superposed epoch analysis of 1464 events of dense (>2 cm–3 at onset) plasma observed by the MPA instruments on board the Los Alamos satellites, for the period 1990–2002. The results allow us to study the temporal evolution of various plasma parameters as a function of local time. We show that dense plasma access to geosynchronous orbit mostly occurs near local midnight. This dense plasma population is shown to be freshly injected from the mid-tail region, colder than the typical plasma sheet and composed of a relatively small O+ component. This population is thus probably the result of a cold, dense plasma sheet (CDPS) injection from the mid-tail region. Cold and dense ion populations are also observed on the dawnside of geosynchronous orbit at a similar epoch time. However, we demonstrate that this latter population is not the result of the dawnward transport of the population detected near midnight. The properties of this ion population may arise from the contribution of both ionospheric upflows and precipitating plasma sheet material. The correlation of an enhanced Kp index with the arrival of the CDPS at geosynchronous orbit shows that the inward transport of this population is allowed by an enhanced magnetospheric convection. Surprisingly, this dense plasma does not, in general, lead to a stronger Dst (ring current strength) within the 12 h following the CDPS injection. It is noted, however, that the superposed Kp index returns to relatively low values soon after the arrival of the CDPS. This may suggest that the dense plasma is, given the average of the 1464 events of this study, only transiting through geosynchronous orbit without accessing the inner regions and, therefore, does not contribute to the ring current. Keywords. Magnetospheric physics (Plasma convection; Plasma sheet) – Space plasma physics (Transport processes)

Instability of the magnetosphere-ionosphere convection and formation of auroral arcs

1994 ◽  
Vol 12 (7) ◽  
pp. 636-641
Author(s):  
A. E. Kozlovsky ◽  
W. B. Lyatsky
Keyword(s):  
Steady State ◽  
Plasma Sheet ◽  
Electron Precipitation ◽  
Ionospheric Conductivity ◽  
Magnetospheric Convection ◽  
The Earth ◽  
Interchange Instability ◽  
Auroral Arcs

Abstract. In this paper we study an instability of the plasma moving towards the Earth near the inner plasma sheet boundary. We include both the interchange instability of the plasma sheet and the magnetosphere-ionosphere interaction instability caused by an effect of field-aligned currents (connected with electron precipitation) on ionospheric conductivity. The instability leads to the separation of steady-state magnetospheric convection into parallel layers. This instability may be responsible for the appearance of quiet auroral arcs inside region 2 of field-aligned currents flowing out of the ionosphere. This instability allows us to explain also the existence of crossing auroral arcs.

Sign in / Sign up

Export Citation Format

Share Document