A review of electrostatic wave measurements on auroral magnetic field lines.

Kelley, M. C.

doi:10.5636/jgg.30.219

Cited by 3 publications

(1 citation statement)

References 63 publications

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“…This suggests that oblique, current-driven shocks should be embedded in regions of ion cyclotron turbulence where there are field-aligned currents of sufficient intensity to excite the n % 0 cyclotron harmonics but not the n = 0 mode. For a review of observations of electrostatic shock structures and of ion cyclotron waves on auroral field lines, see Kelley [1979]. From (16) and the definition of the coordinate • it can be seen that when the shock normal becomes parallel to the magnetic field, a --0 and • --z, the equations describing the double layer are recovered.…”

Section: __ F Fe( V Ii L)v ]1 I Dv Jjlmentioning

confidence: 99%

Mechanisms for auroral precipitation: A review

Swift¹

1981

Reviews of Geophysics

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Theories for and observations relating to auroral precipitation are reviewed for purposes of assessing our understanding of the aurora and of identifying those processes which play the most important role in auroral precipitation. For purposes of the review, four categories of auroral forms are defined: (1) the diffuse aurora, which usually forms the equatorward boundary of the auroral oval, (2) auroral patches and pulsations, which appear most commonly within the morning sector of the diffuse aurora, (3) the discrete aurora, most prominently observed in the evening and poleward sectors of the auroral oval, and (4) the 'inverted-V' aurora, which appears in the same regions as discrete aurora but with much larger size scales. One principal conclusion is that the diffuse aurora, likely caused by both proton and electron precipitation, is the result of pitch angle scattering by electrostatic cyclotron waves. Another is that the auroral pulsations and patches are the result of pitch angle scattering of more energetic electrons by electromagnetic whistler mode waves. The patches may represent flux tubes of enhanced ionization tied to the lower ionosphere. The discrete aurora is the result of electron acceleration parallel to the magnetic field by the quasi-static electric field of a current-driven laminar electrostatic V shock. The theory for inverted-V precipitation is not well developed, but observations strongly suggest that it is related to ion cyclotron anomalous resistivity. INTRODUCTIONEver since the first sounding rockets penetrated the upper atmosphere over 20 years ago it has been known that the visible aurora has been caused by electron and proton impact upon the upper atmosphere. It has only been within the past few years that any fundamental understanding of the processes responsible for the precipitation of charged particles has emerged. The purpose of this revi• is to assess the state of of plasma instabilities to auroral problems. Although this analysis quantitatively treats a well-defined plasma model, some of the assumptions required for the instability to develop and some of the consequences of the theory have not been borne out by observations. Rather than presenting an exhaustive analysis of all precipitation mechanisms proposed in the literature, this review presents a critical assessment of current ideas for which there exists compelling observational eviour understanding of auroral particle precipitation and to at-dence. These ideas and the theories formulated from them are tempt to identify those processes which are likely to pla• a sig-' described in some detail. nificant role in auroral precipitation. This will involve both aThe aurora has such a variety of temporal and spatial size critical examination of the predictions of the various theoretical mechanisms for auroral precipitation and a review of observations relevant to the precipitation process.There are two basic types of precipitation processes: (1) ac-•:eleration into the atmosphere by quasi-stationary electric fields with a compone...

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Section: __ F Fe( V Ii L)v ]1 I Dv Jjlmentioning

confidence: 99%

Mechanisms for auroral precipitation: A review

Swift¹

1981

Reviews of Geophysics

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Prediction and theory evaluation: Alfven on space plasma phenomena

Brush

1990

EoS Transactions

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According to some scientists and philosophers of science, a theory is or should be judged by its ability to make successful predictions. This paper examines a case from the history of recent science—the research of Hannes Alfvén and his colleagues on space plasma phenomena—in order to see whether scientists actually follow this policy. Tests of five predictions are considered: magnetohydrodynamic waves, field‐aligned (“Birkeland”) currents, critical ionization velocity and the existence of planetary rings, electrostatic double layers, and partial corotation. It is found that the success or failure of these predictions had essentially no effect on the acceptance of Alfvén's theories, even though concepts such as “Alfvén waves” have become firmly entrenched in space physics. Perhaps the importance of predictions in science has been exaggerated; if a theory is not acceptable to the scientific community, it may not gain any credit from successful predictions.

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Alfven's programme in solar system physics

Brush

1992

IEEE Trans. Plasma Sci.

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A review of electrostatic wave measurements on auroral magnetic field lines.

Cited by 3 publications

References 63 publications

Mechanisms for auroral precipitation: A review

Mechanisms for auroral precipitation: A review

Prediction and theory evaluation: Alfven on space plasma phenomena

Alfven's programme in solar system physics

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