Formation of field-aligned irregularities in the magnetosphere

doi:10.1016/0021-9169(71)90027-4

Journal of Atmospheric and Terrestrial Physics

Volume 33, Issue 5, May 1971, Pages 741-750

Journal of Atmospher...

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Abstract

The general physics of field-aligned irregularities in the magnetosphere is studied. Then a specific mechanism is proposed for formation of irregularities. It involves a spatially varying electrostatic field orthogonal to B and operates in conjunction with irregularities of conductivity in the E region, and field-aligned currents caused by mismatch of conjugate ionospheric potentials. The mechanism functions most easily at night and in equatorial regions. An application to the formation of spread F is discussed.

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Cited by (48)

The impact of cold electrons and cold ions in magnetospheric physics
2021, Journal of Atmospheric and Solar-Terrestrial Physics
Citation Excerpt :
The formation of ducts seems to be associated with convection: as soon as magnetospheric convection increases, the plasmasphere is observed to suddenly become structured (Borovsky and Denton, 2008) and density ducts have been observed to form when traveling ionospheric disturbances pass (Loi et al., 2016). Ideas about the causes of the density ducts include (1) interchange instabilities (Cole, 1971; Jacobson et al., 1996; Pierrard and Lemaire, 2004; Buzulukova et al., 2008), (2) thunderstorm electric fields (Park and Helliwell, 1971; Rodger et al., 1998), (3) ionospheric feedback (Park and Banks, 1974), and (4) ULF waves (Adrian et al., 2004). For density structures near the plasmapause, the drift-wave instability (Hasegawa, 1971) and the pressure-gradient instability (Richmond, 1973) have been considered.
A review of the impact of the cold-ion and cold-electron populations in the Earth’s magnetosphere is presented. The cold populations are defined by total energy less than approximately 100 eV, i.e. in the energy range which is strongly affected by spacecraft charging and that often dominates the total plasma density. We also include the warm plasma cloak in the review, since it overlaps partially with the cold energy range and is a population that is still not well understood.
The known impacts of cold ions and cold electrons that are discussed are: the source of hot magnetospheric plasma, solar-wind/magnetosphere coupling, magnetotail reconnection and substorms, Kelvin–Helmholtz instabilities on the magnetopause, chorus, hiss, electromagnetic-ion-cyclotron and ultra-low-frequency wave–particle interactions, aurora structuring and spacecraft charging. Other possible impacts are associated with refilling on open-drift trajectories, the remnant layer and plasmapause disruption. A discussion of the difficulty of cold-plasma measurements and the need for new measurement techniques that measure the full cold-ion and cold-electron distribution functions is also presented.
There remain a lot of unknowns about the cold-ion and cold-electron populations, associated with their origin, properties, drivers and impacts. These populations will need to be fully understood before the magnetosphere–ionosphere system can be fully understood.
Characteristics of the equatorial F-region vertical plasma drift observed during post-sunset and pre-sunrise hours
2010, Advances in Space Research
Post-sunset and pre-sunrise vertical plasma drifts at the equatorial F-region have been investigated using the HF Doppler radar and ionosonde observations. Observed vertical plasma drift features during the sunrise are found to complement that observed during the evening. The post-sunset vertical plasma drift is characterized by an upward enhancement, a pre-reversal enhancement and a reversal in the drift direction. Similarly, the pre-sunrise plasma drift is characterized by a sudden downward excursion followed by an upward turning. The wavelet analysis of the plasma drift shows the presence of fluctuations in the period range 4–32 min and the short period fluctuations are attributed to the atmospheric gravity waves.
Magnetic storm effects in H and D components of the geomagnetic field at low and middle latitudes
2005, Journal of Atmospheric and Solar-Terrestrial Physics
The paper describes the storm time (D_st) variations in horizontal (H) and eastward (Y) components of the geomagnetic field at stations along the Indo-Russian longitude sector. The location of stations extends from magnetic equator to polar latitudes but confined within narrow range of longitudes, thereby the results are not affected by any longitudinal inequalities. Both H and Y are shown to be significantly affected by magnetic storms. The storm time variation in H followed fairly well with the corresponding variation of D_st index, decreasing with increasing latitude, but the magnitude of $Δ Y$ increases with increasing latitude of the station. Further the D_st in Y was confined to period of the main phase when interplanetary magnetic field was southward. Thus, the recovery in Y is faster than that in H. Simultaneous changes of $Δ Y$ and $Δ H$ follow the relation $Δ Y = Δ H \sin (Ψ - D)$ where $Ψ$ and D are the dipole and dip declinations at the station. The fluctuations in $Δ Y$ show better relationship with AE index than with D_st index. It is suggested that the ring current is energized occasionally by the injection of particles from even the sub-auroral latitudes along the earth's magnetic field lines.
Whistler ducts and geomagnetic pulsation resonant field line shells near L = 2 - Are they identical?
1997, Journal of Atmospheric and Solar-Terrestrial Physics
Data from the processing of about 1700 whistlers recorded in Tihany (L-value of propagation, equatorial electron density and tube content) are compared with geomagnetic pulsation characteristics (mainly of periods) as recorded at the nearby Nagycenk Observatory (L∼2). In addition, the number of whistlers recorded at Panska Ves (Czech Republic) for more than ten years (1971–1979, 1987, 1990) are compared with the Nagycenk pulsation activity. Both results can be reconciled with the supposition that whistler ducts and geomagnetic field line shells are closely connected with each other as they appear simultaneously with enhanced probability, and the position of these structures is similar within the magnetosphere.
A new role for the plasmaphere in "quiet" ionospheric electrodynamics
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Global scale longitudinal gradients of pressure in the plasmasphere may be formed naturally by ionospheric processes, or caused by electrostatic fields of ionospheric dynamo origin. It is shown that plasmaspheric gradients of pressure, orthogonal both to the magnetic field (B) and to grad B, generate geophysically significant field-aligned currents. Considering the ionosphere and plasmasphere as a coupled electrodynamic system, these currents alter non-negligibly the self-consistent ionospheric electric field and current. Criteria are established for this coupling mechanism (a kind of plasmaspheric impedance) to be significant. This has implications for the relationships of ionospheric electric fields and currents, F-region drifts, and magnetic variations, due to upper atmosphere tides and winds.
Post-sunset F-region vertical velocity variations at magnetic equator
1994, Journal of Atmospheric and Terrestrial Physics
The vertical drift velocity of the F-region in the post-sunset period at the magnetic equatorial station Trivandrum has been studied using a HF phase path sounder. The study revealed the presence of quasi-periodic fluctuations with periods in the range 4 30 min superposed on a steady vertical motion as a regular feature of the equatorial F-region in the post-sunset period. The fluctuations in the vertical velocity arc attributed to the east west electric field fluctuations generated by internal atmospheric gravity waves. The vertical velocity fluctuations can provide the necessary seed perturbations for the growth of equatorial spread-F irregularities.

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Formation of field-aligned irregularities in the magnetosphere

Abstract

Planet. Space Sci.

J. Atmos. Terr. Phys.

J. Atmos. Terr. Phys.

J. Atmos. Terr. Phys.

J. geophys. Res.

Phil. Trans. Roy. Soc.

Research in Geophysics

J. geophys. Res.

Review of geophys.

Aust. J. Phys.

J. geophys. Res.

J. geophys. Res.