Formation of density troughs embedded in the outer plasmasphere by subauroral ion drift events

Ober, D. M.; Horwitz, J. L.; Gallagher, D. L.

doi:10.1029/97ja01046

Cited by 96 publications

(125 citation statements)

References 24 publications

(20 reference statements)

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“…The equatorial plasmaspheric electron density is calculated using the dynamic global core plasma model of Ober et al [1997]. This model is basically the same as the time-dependent model of Rasmussen et al [1993], which was used in our previous studies, except the Ober et al model is linked with a self-consistent electric field, while the Rasmussen et al model is driven by the Volland-Stern convection field [Volland, 1973;Stern, 1975] LANL [e.g., Jordanova et al, 2006].…”

Section: Used Approaches and Initial And Boundary Conditionsmentioning

confidence: 99%

Model of electromagnetic ion cyclotron waves in the inner magnetosphere

et al. 2014

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Citation:Gamayunov, K. V., M. J. Engebretson, M. Zhang, and H. K. Rassoul (2014) Abstract The evolution of He + -mode electromagnetic ion cyclotron (EMIC) waves is studied inside the geostationary orbit using our global model of ring current (RC) ions, electric field, plasmasphere, and EMIC waves. In contrast to the approach previously used by Gamayunov et al. (2009), however, we do not use the bounce-averaged wave kinetic equation but instead use a complete, nonbounce-averaged, equation to model the evolution of EMIC wave power spectral density, including off-equatorial wave dynamics. The major results of our study can be summarized as follows. (1) The thermal background level for EMIC waves is too low to allow waves to grow up to the observable level during one pass between the "bi-ion latitudes" (the latitudes where the given wave frequency is equal to the O + -He + bi-ion frequency) in conjugate hemispheres. As a consequence, quasi-field-aligned EMIC waves are not typically produced in the model if the thermal background level is used, but routinely observed in the Earth's magnetosphere. To overcome this model-observation discrepancy we suggest a nonlinear energy cascade from the lower frequency range of ultralow frequency waves into the frequency range of EMIC wave generation as a possible mechanism supplying the needed level of seed fluctuations that guarantees growth of EMIC waves during one pass through the near equatorial region. The EMIC wave development from a suprathermal background level shows that EMIC waves are quasi field aligned near the equator, while they are oblique at high latitudes, and the Poynting flux is predominantly directed away from the near equatorial source region in agreement with observations. (2) An abundance of O + strongly controls the energy of oblique He + -mode EMIC waves that propagate to the equator after their reflection at bi-ion latitudes, and so it controls a fraction of wave energy in the oblique normals. waves generated by RC O + in the region L ≈ 2-3 may have an implication to the energetic particle loss in the inner radiation belt.

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Section: Used Approaches and Initial And Boundary Conditionsmentioning

confidence: 99%

Model of electromagnetic ion cyclotron waves in the inner magnetosphere

et al. 2014

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“…Such drift events are called subauroral polarization streams (SAPS), or subauroral ion drift (SAID) when the drift becomes more localized and intense, in excess of 1 km/s (Galperin et al, 1973;Smiddy et al, 1977;Spiro et al, 1979;Rich et al, 1980;Filippov et al, 1984;Anderson et al, 1993Anderson et al, , 2001PuhlQuinn et al, 2007). The ionospheric ion and electron temperature is enhanced, while the electron content and conductivity tend to be low (Galperin et al, 1986;Deminov and Shubin, 1988;Filippov et al, 1989;Anderson et al, 1991;Rodger et al, 1992;Ober et al, 1997;Figueiredo et al, 2004;Prölss, 2006), so that less power is drawn from the generator. A range of diverging field strengths exists (Karlsson et al, 1998); very strong fields and the associated drifts might produce stable auroral red arcs as a consequence of the ion and electron heating due to ion-neutral collisions (Hoch and Lemaire, 1974;Foster et al, 1994;Moffett et al, 1998).…”

Section: Discussionmentioning

confidence: 99%

“…A range of diverging field strengths exists (Karlsson et al, 1998); very strong fields and the associated drifts might produce stable auroral red arcs as a consequence of the ion and electron heating due to ion-neutral collisions (Hoch and Lemaire, 1974;Foster et al, 1994;Moffett et al, 1998). SAPS and SAID have substantial effects on the plasmasphere and the ring current, and on the overall configuration of the inner magnetosphere (Foster et al, 1994;Ober et al, 1997;De Keyser, 1999;Goldstein et al, 2003Goldstein et al, , 2005Gurgiolo et al, 2005;Foster et al, 2007;Voiculescu and Roth, 2008).…”

Section: Discussionmentioning

confidence: 99%

Auroral and sub-auroral phenomena: an electrostatic picture

Keyser

Echim

2010

Ann. Geophys.

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Abstract. Many auroral and sub-auroral phenomena are manifestations of an underlying magnetosphere-ionosphere coupling. In the electrostatic perspective the associated auroral current circuit describes how the generator (often in the magnetosphere) is connected to the load (often in the ionosphere) through field-aligned currents. The present paper examines the generic properties of the current continuity equation that characterizes the auroral circuit. The physical role of the various elements of the current circuit is illustrated by considering a number of magnetospheric configurations, various auroral current-voltage relations, and different types of behaviour of the ionospheric conductivity. Based on realistic assumptions concerning the current-voltage relation and the ionospheric conductivity, a comprehensive picture of auroral and sub-auroral phenomena is presented, including diffuse aurora, discrete auroral arcs, black aurora, and subauroral ion drift. The electrostatic picture of field-aligned potential differences, field-aligned currents, ionospheric electric fields and plasma drift, and spatial scales for all these phenomena is in qualitative agreement with observations.

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“…They were able to reproduce the observed undulation and suggested that substorm injection, shielding and convection fields all play a role. We revisited this problem and examined in detail the effects of magnetosphere-ionosphere coupling and inductive electric field on the formation of plasmaspheric undulation with the CRCM model and Ober et al (1997) model of plasmasphere (Buzulukova et al, 2008).…”

Section: Crcm With Plasmasphere Model and Plasmapause Undulationsmentioning

confidence: 99%

“…They found shortly after a substorm onset at 1900 UT, the plasmasphere ripple was propagating westward along the plasmapause. Fok et al (2005) used the combined models of the CRCM and the dynamic plasmasphere model of Ober et al (1997) to simulate this event. They were able to reproduce the observed undulation and suggested that substorm injection, shielding and convection fields all play a role.…”

Section: Crcm With Plasmasphere Model and Plasmapause Undulationsmentioning

confidence: 99%