Geomagnetic micropulsations and diagnostics of the magnetosphere

Troitskaya, V. A.; Gulelmi, A. V.

doi:10.1007/bf00542894

Cited by 165 publications

(85 citation statements)

References 65 publications

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“…Attempts to do so, assisted by a priori assumptions of equatorial plasma concentration profiles, were reported about the same time that whistlers were being used for studying plasmaspheric plasma density [Obayashi and Jacobs, 1958;Westphal and Jacobs, 1962;Troitskaya and Gul'elmi, 1967]. An important development, relevant to the present paper was the realization by Gul'elmi [1966] that the toroidal ULF wave mode could provide local parameters of the plasma distribution without the need for a plasma density model.…”

Section: Introductionmentioning

confidence: 99%

A technique to investigate plasma mass density in the topside ionosphere using ULF waves

Price¹,

Waters²,

Menk³

et al. 1999

J. Geophys. Res.

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Abstract. The relatively cold core plasma density in the region where the ionosphere mixes with the plasmasphere is difficult to probe experimentally. It is shown that resonances of ULF magnetohydrodynamic waves can provide unique information on plasma mass density in the region where the ionosphere and plasmasphere merge. The technique depends on the detection of harmonics of ULF field line resonances and allows the determination of plasma mass densities at discrete locations along a magnetic field line without assuming any function for plasma distribution along the field. The plasma mass densities obtained from ULF harmonics at L= 1.8 are compared with several plasma mass density models of this region. In addition to describing and illustrating the technique, the method is critically examined for its limitations. These include the finite number of ULF harmonics that can be detected, the complexity of the nonlinear solving scheme, the consequences of using the method at larger L values, and approximating the system of equations with a finite difference scheme. It is shown that the technique can provide independent estimates of plasma mass densities at discrete, magnetic field-aligned altitudes, which gives an additional experimental check on theoretical models that predict the dynamics of plasma from the topside ionosphere to the inner plasmasphere.

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Section: Introductionmentioning

confidence: 99%

A technique to investigate plasma mass density in the topside ionosphere using ULF waves

Price¹,

Waters²,

Menk³

et al. 1999

J. Geophys. Res.

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“…Reviews of previous work in the field of geomagnetic micropulsations have been given by Campbell (1967), Troitskaya (1967), andSaito (1969).…”

Section: Introductionmentioning

confidence: 99%

Broad Band Micropulsation Activity at a Geomagnetic Midlatitude Station

Frey

Fischer

Maple

et al. 1971

J. geomagn. geoelec

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The relationships of broad band geomagnetic micropulsations (periods from 20-300 sec.) at Strawberry Hill, Concord, Mass, to some magnetospheric, interplanetary, and solar phenomena are examined to ascertain possible locations of energy sources for their excitation. The micropulsation activity is characterized by a one-hour, quasi-logarithmic index, M, which is chiefly a measure of hydromagnetic (HM) wave amplitudes. The strong diurnal variation in the HM wave energy continues to elude adequate explanation.However, it is apparent that the excitation of these waves is favored in the daylight hemisphere. High micrapulsation activity levels generally obtain during periods of sustained magnetic disturbance, but several exceptions preclude the existence of a direct cause-and-effect relationship. Indirect evidence suggests the importance of magnetospheric convection in controlling the micropulsation activity level. Daily micropulsation activity levels are more closely related to interplanetary magnetic field variability than to daily angle of the interplanetary magnetic field vector in solar ecliptic coordinates) and micropulsation activity is indicated by the present study. Superposed epoch analysis reveals an association of highly disturbed micropulsation days with the central meridian passage (CMP), 3 to 5 days earlier, of solar regions characterized by low levels of calcium plage activity. It is suggested that high micropulsation activity levels are more closely associated with the CMP of unipolar magnetic regions (UMR) than are high geomagnetic activity levels.

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“…In fact, a few recent studies have presented evidence for Pc1 wave bursts that are ground. One related empirical fact is that the relative variation of the product of the repetition period 1. and the wave frequency f is less than the relative variations of f and 1. separately, which has led to the long-held conclusion that the product 1.f is roughly constant at about 100 (where the times are given in seconds) (for early papers, see, e.g., Troitskaya and Guglielmi [1967] …”

Section: Introductionmentioning

confidence: 99%

New constraints on theories of Pc1 pearl formation

Мурсула¹,

Kangas²,

Kerttula³

et al. 1999

J. Geophys. Res.

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Abstract. In this paper we study structured Pcl pulsations (also called Pcl pearls) observed on ground, concentrating on the relation between the pearl repetition period •-and the wave frequency f. Earlier studies suggest that the product •-f is roughly constant. We reexamine this relation and show that a simple inverse law is excluded. Instead, our observations suggest the relation •-c• f-P, with p -0.59 4-0.06, posing a new, strict constraint on theories of Pc1 pearl formation. We also study the L dependence of various combinations of •-and f using a model L value and extract additional constraints from these• combinations. We discuss these constraints in the bouncing wave packet model of pearl formation and determine the range of allowed parameter values in this model. We present two models of energetic ions with different L distributions and show that one of them can be excluded by the constraints derived. We also discuss how to further improve on these constraints to better test the bouncing wave packet model and other theories of Pc1 pearl formation.

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Geomagnetic micropulsations and diagnostics of the magnetosphere

Cited by 165 publications

References 65 publications

A technique to investigate plasma mass density in the topside ionosphere using ULF waves

A technique to investigate plasma mass density in the topside ionosphere using ULF waves

Broad Band Micropulsation Activity at a Geomagnetic Midlatitude Station

New constraints on theories of Pc1 pearl formation

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