Restoration of the meridional structure of geomagnetic pulsation fields from gradient measurements

Baransky, L.; Belokris, S.P.; Borovkov, Y.E.; Гохберг, М. Б.; Fedorov, E. N.; Green, C.A.

doi:10.1016/0032-0633(89)90136-0

Cited by 34 publications

(28 citation statements)

References 11 publications

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“…Experimental determination of the spectral parameters of ULF pulsation makes it possible to solve, in principle, the inverse problem to determine the plasma distribution in the magnetosphere and the Pedersen conductivity in the ionosphere. Despite the extreme simplicity of the original resonance model (Southwood, 1974;Chen and Hasegawa, 1974), the theoretically predicted amplitude-phase meridional structure corresponds well to experimental observations of the local structure of various types of ULF waves at sub-auroral and middle latitudes: Pe5 (Walker et al, 1979), Pc4 (Green, 1978;Baransky et al, 1985Baransky et al, , 1989, Pc3 (Fukunishi and Lanzerotti, 1974a;Best et al, 1986) and even Pi2 (Kurchashov et al, 1987). It was found that the occurrence region of Alfven resonance existence spreads at rather low latitudes.…”

Section: Introductionsupporting

confidence: 74%

Gradient and Polarization Methods of Ground-Based Monitoring of Magnetospheric Plasma.

Baransky¹,

Green

Fedorov³

et al. 1995

J. geomagn. geoelec

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The methods of an unambiguous determination of the parameters of the magnetospheric resonator (resonance frequency, its meridional gradient, and width of the resonance) by studying the spatial structure of ULF waves, in the Pc3-4 frequency range, are summarized and reviewed. The methods considered are the gradient technique (synchronous measurements of ULF field at two nearby stations) andthe polarization method (multicomponentobservations atone station). Bothmethods are experimentally tested using the data from an experiment at low latitude (L = 1.5). Taking into account modifications of the structure of the ULF magnetic field due to geoelectric inhomogeneities, both methods demonstrate consistent results and are in a qualitative agreement with theoretical predictions. These methods should provide a useful tool for monitoring resonant frequencies and the distribution of plasma in the magnetosphere.

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Section: Introductionsupporting

confidence: 74%

Gradient and Polarization Methods of Ground-Based Monitoring of Magnetospheric Plasma.

Baransky¹,

Green

Fedorov³

et al. 1995

J. geomagn. geoelec

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“…The 'gradient methods' (Baransky et al, 1989;Waters et al, 1991;Kawano et al, 2002) are designed to extract FLR from ground magnetometer data using two stations closely spaced along the same meridian. In this paper, we distinguished FLRs by applying the gradient methods to the storm-time data using ground magnetometers at L ∼ 1.4.…”

Section: Discussionmentioning

confidence: 99%

“…The concept of the crossphase technique (as named by Waters et al (1991)) was first proposed by Baransky et al (1989). The phase of the H -component jumps by 180 degrees across the resonance point (Baransky et al, 1985).…”

Section: Discussionmentioning

confidence: 99%

A significant mass density increase during a large magnetic storm in October 2003 obtained by ground-based ULF observations at L ≈ 1.4

et al. 2006

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During 28-31 October, 2003, a series of coronal mass ejections hit the magnetosphere and triggered two consecutive large storms. Three ground magnetometers at L = 1.32-1.41 recorded field-line resonances (FLRs) during this interval. The FLR frequencies decreased from 0600 LT on 31 October 2003 during the main phase of the second storm until 12 LT when the recovery phase of this storm began. After the decrease, the FLR frequencies returned to its pre-storm value (at 0600 LT on 31 Oct.) in a few hours. The measured decrease in the FLR frequency suggests a relative increase in mass density along the field lines during the magnetic storm. On the other hand, the total electron content (TEC) data suggest that the ionospheric plasma number density during this storm was similar to that during quiet times. A possible explanation for the increase in mass density would be an outflow of the heavy ions (e.g., O + ) from the ionosphere to the plasmasphere.

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“…These methods utilize the characteristic feature of FLRgenerated ULF waves: Since the amplitude and phase of FLR-generated ULF waves sharply changes across the resonance latitude while the superposed signals are more global and almost the same at the two stations, taking the difference of the data from the two adjacent stations can cancel out the most of the non-FLR signals and extract even weak FLR signals. These methods have been applied to Pc3-4 pulsation data from two ground stations in middle to low latitudes, and the FLR parameters at a point (usually regarded as the midpoint) between the two stations have been successfully obtained (e.g., Baransky et al, 1985Baransky et al, , 1989Kurchashov et al, 1987;Green et al, 1993;Waters et al, 1994;Russell et al, 1999;Chi et al, 2000;Menk et al, 2000).…”

Section: Introductionmentioning

confidence: 99%

Hodograph method to estimate the latitudinal profile of the field-line resonance frequency using the data from two ground magnetometers

2013

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The hodograph method enables estimating the latitudinal profile of the field-line resonance (FLR) frequency ( f R ) using the data from two ground magnetometers. This paper provides the full details of this method for the first time, and uses a latitudinal chain of ground magnetometers to examine its validity and usefulness. The hodograph method merges the widely-used amplitude-ratio and cross-phase methods in a sense that the hodograph method uses both the amplitude ratio and the phase difference in a unified manner; further than that, the hodograph method provides f R at any latitude near those of the two ground magnetometers. It is accomplished by (1) making a complex number by using the amplitude ratio (phase difference) as its real (imaginary) part; (2) drawing thus obtained complex numbers (one number for one frequency) in the complex plane to make a hodograph; and (3) fitting to thus obtained hodograph a model satisfying the FLR condition, which is a circle with the assumption that the resonance width is independent of the latitude. To examine the validity and usefulness of the hodograph method, we apply it to a Pc 4 event observed by the Scandinavian BEAR array. We also apply the amplitude-phase gradient method (Pilipenko and Fedorov, 1994;Kawano et al., 2002) to the same event, and compare the results; this is the first article applying the both methods to the same dataset.

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Restoration of the meridional structure of geomagnetic pulsation fields from gradient measurements

Cited by 34 publications

References 11 publications

Gradient and Polarization Methods of Ground-Based Monitoring of Magnetospheric Plasma.

Gradient and Polarization Methods of Ground-Based Monitoring of Magnetospheric Plasma.

A significant mass density increase during a large magnetic storm in October 2003 obtained by ground-based ULF observations at L ≈ 1.4

Hodograph method to estimate the latitudinal profile of the field-line resonance frequency using the data from two ground magnetometers

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