Magnetic field inclination angle at geosynchronous orbit

Lin, C. S.; Barfield, J. N.

doi:10.1016/0032-0633(84)90071-0

Cited by 15 publications

(8 citation statements)

References 12 publications

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“…The notation is as follows: N is the number of data points in the set; B is the r.m.s, external field; 2 is the r.m.s, residual field given by (A4); cl,c~, and c 3 are the coefficients defining the contribution from the intramagnetospheric current sheet and corresponding to three terms derived from potentials (50)-(52); arc is the scale radius of the ring current and 7Rc is a quantity defining its noon-midnight asymmetry; D is the nightside current sheet thickness (Tsyganenko, 1989a) One of the most surprising results concerns the characteristic half-thickness of the tail current sheet. Much more likely, the main contribution to this effect is made by a considerable decrease of the B:com- (Lin and Barfield, 1984) with those predicted by three models for different local times. As can be seen from Table I, the corresponding parameter D falls from D ~ 2.1 at Kp = 0, 0 + to D ~ 0.3 at Kp ~ 5 -.…”

Section: Table Imentioning

confidence: 78%

Quantitative models of the magnetospheric magnetic field: Methods and results

Tsyganenko

1990

Space Sci Rev

128

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The paper reviews various approaches to the problem of evaluation and numerical representation of the magnetic field distributions produced within the magnetosphere by the main electric current systems including internal Earth's sources, the magnetopause surface current, the tail plasma sheet, the large-scale systems of Birkeland current, the currents due to radiation belt particles, and the partial ring current circuit. Some basic physical principles as well as mathematical background for development of magnetospheric magnetic field models are discussed.A special emphasis is placed on empirical modeling based on datasets created from large bodies of spacecraft measurements. A review of model results on the average magnetospheric configurations and their dependence on the geomagnetic disturbance level and the state of interplanetary medium is given. Possibilities and perspectives for elaborating the 'instantaneous' models capable of evaluating a current distribution of magnetic field and force line configuration based on a synoptic monitoring the intensity of the main magnetospheric electric current systems are also discussed. Some areas of practical use of magnetospheric models are reviewed in short. Magnetospheric plasma and energetic particle measurements are considered in the context of their use as an independent tool for testing and correcting the magnetic field models. QUANTITATIVE MODELS OF THE MAGNETOSPHERIC MAGNETIC FIELD 81 \ J ./~ I J J f J ;t=O Z 25' 20 15 Z Rv J I J \ \ \ / / J Kp >_.5-J ~v jn J L;O .... f-

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Section: Table Imentioning

confidence: 78%

Quantitative models of the magnetospheric magnetic field: Methods and results

Tsyganenko

1990

Space Sci Rev

128

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“…A statistical analysis of the inclination angle I at the geosynchronous orbit has been done by using the satellite GOES 2 and 3 [Lin and Barfield, 1984]. They have shown that in 1200 ~ 1800 LT the magnetic field during disturbed condition (Kp=4~9) is distended and becomes tail-like configuration as compared with that during geomagnetically quiet condition (Kp=4~9).…”

Section: Occurrence Of the Compressional Pc 5 Wavesmentioning

confidence: 99%

Waveform and polarization of compressional Pc 5 waves at geosynchronous orbit

Higuchi¹,

Kokubun²

1988

J. Geophys. Res.

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The statistical characteristics of compressional Pc 5 waves are studied using magnetic field data obtained by GOES 2 and 3 geosynchronous satellites during 2‐year period of August 1978 to August 1980. Depending on the second‐harmonic component in the compressional component of the magnetic field oscillation, the compressional Pc 5 waves are classified into the three types: the harmonic, transitional and normal types. It is found that the harmonic and transitional types have significant azimuthal perturbations and show right‐handed polarization with respect to the local magnetic field. The occurrence of these types is limited to the region close to the effective equator in local time sector of 1500 ∼ 1700 LT, associated with a depression in the local field magnitude during geomagnetically active periods. Most of the normal type have small amplitude in the azimuthal component. However, when the normal type (corresponding to compressional Pc 5 waves examined in previous works) has a large azimuthal perturbation, it shows the left‐handed polarization. We try to find factors relating results to the excitation mechanisms developed in the past few years. Especially, we focus on the polarization properties of transverse perturbation which may reflect the spatial inhomogeneity of the media through the finite amplitude effect. It is suggested that the polarization of the transverse perturbation of compressional Pc 5 waves arises from that of the Alfvén mode.

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“…The structure of the geomagnetic field and plasma in this region is extremely variable because the region lies at the boundary between the "spheres of influence" of the Earth's internal currents and the magnetotail currents. It has been remarked for many years [Sugiura, 1972;Hedgecock and Thomas, 1975;Lin and Barfield, 1984;Kaufmann, 1987;Fairfield et al, 1987;Pulkkinen et al, 1991] that taillike fields can often be observed at synchronous orbit, implying that an intense thin current sheet can approach close to Earth, (possibly reaching earthward of geosynchronous orbit). Thus, while tracing field lines is fully recognized as a matter of general importance in magnetospheric research, it is particularly important in the regions of synchronous orbit and the auroral zones.…”

Section: Introductionmentioning

confidence: 99%

Observational determination of magnetic connectivity of the geosynchronous region of the magnetosphere to the auroral oval

Hones¹,

Thomsen²,

Reeves³

et al. 1996

J. Geophys. Res.

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This is a report of a program to study the magnetic connectivity between the auroral region of the ionosphere and the equatorial geosynchronous region of the magnetosphere. The program uses plasma measurements made with polar orbiting Defense Meteorological Satellite Program (DMSP) satellites and several geosynchronous satellites, seeking time intervals when nearly identical plasma electron spectra (32 eV to 30 keV) indicate magnetic connectivity between a polar/geosynchronous satellite pair. When such signatures of connectivity are found, the locations of the relevant satellite pair are compared with the locations that would be predicted by a magnetospheric model. Here we report results from the initial application of this program that uses data from DMSP F‐8, F‐9 and F‐10 polar satellites and the synchronous satellites 1989‐046 and 1990‐095 acquired in the 6‐day interval March 7–12, 1991. The results are compared with predictions of the T89a model [Tsyganenko, 1989; Peredo et al., 1993]. Orbital calculations predicted 96 close conjunctions among these satellites during the interval. Of those we have made spectral comparisons for 47, finding 20 for which close spectral similarity occurred during few‐second intervals. Ionospheric footpoints of the satellite pairs calculated by the T89a model for these intervals revealed eight for which the discrepancy between the DMSP latitude at “best spectral match” and the model projection of the synchronous satellite was smaller than 1°. However, there were five intervals for which the discrepancy was greater than 6°. The latter were all found in the local time interval 0700–0900, perhaps indicating a particular inadequacy of the T89a model in that region. This initial work also supports the view that the auroral oval of discrete arcs is an ionospheric mapping of the full thickness of the plasma sheet (e.g., Feldstein and Galperin, 1985) and not just of the plasma sheet boundary layer (e.g., Eastman et. al., 1985). During just its first few years of concurrent operation this constellation of well‐instrumented synchronous and polar‐orbiting satellites has provided data for literally thousands of close conjunctions such as we analyze in this report. Thus an algorithm is developed enabling the verification and testing of proposed mappings between the ionosphere and magnetosphere (such as T89a).

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Magnetic field inclination angle at geosynchronous orbit

Cited by 15 publications

References 12 publications

Quantitative models of the magnetospheric magnetic field: Methods and results

Quantitative models of the magnetospheric magnetic field: Methods and results

Waveform and polarization of compressional Pc 5 waves at geosynchronous orbit

Observational determination of magnetic connectivity of the geosynchronous region of the magnetosphere to the auroral oval

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