G. Rostoker

University of Alberta

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Co-Authors

J. C. Samson

University of Alberta

Y. Kamide

Science Museum

G. D. Reeves

Los Alamos National Laboratory

C. T. Russell

University of California, Los Angeles

H. J. Singer

National Oceanic and Atmospheric Administration

R. P. Lepping

Goddard Space Flight Center

A. T. Y. Lui

Johns Hopkins University Applied Physics Laboratory

S. Kokubun

Sendai Nishitaga National Hospital

W. Baumjohann

Space Research Institute

R. L. McPherron

Planetary Science Institute

Cooperative Institutions

Goddard Space Flight Center

Johns Hopkins University Applied Physics Laboratory

University of California, Los Angeles

University of California, Berkeley

Planetary Science Institute

University of Alberta

Nagoya University

University of Iowa

Johns Hopkins University

Charles River Laboratories (Netherlands)

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Magnetic flux mapping considerations in the auroral oval and the Earth's magnetotail

Journal of Geophysical Research Atmospheres (1993)

G. Rostoker S. Skone

The prevalent theory describing the entry of solar wind energy into the magnetosphere involves the merging of solar wind and terrestrial magnetic field lines on the dayside magnetopause and the subsequent reconnection of those field lines across the neutral sheet in the Earth's magnetotail. The reconnection is thought to occur at a neutral line, whose location is often set at ∼100 Re behind the Earth. The location of this neutral line has not been verified experimentally to date, and in this paper we shall provide some constraints suggesting its average location to lie in the range −50>X>−80 Re. We shall use AMPTE, ISEE, and IMP 8 magnetic field data to evaluate the fall off of Bz at the position of the neutral sheet as one moves back into the tail. From these measurements we construct an analytical representation of Bz as a function of downtail position. Using the Coroniti and Kennel relationship for the flaring of the magnetotail, we evaluate the average position of the equatorward edge of the polar cap, which we then assume to represent the poleward edge of the average auroral oval. From flux conservation considerations, we then evaluate the average width of the auroral oval. We conclude the paper by discussing how the mapping from the magnetotail is reflected in the scale sizes of auroral features in the midnight sector of the auroral oval.

Plasma sheet

Field line

Substorm

Current sheet

Line (geometry)

10.1029/92ja01838

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Citations (38)

Regions of negative B_z in the Tsyganenko 1989 Model Neutral Sheet

Journal of Geophysical Research Atmospheres (1992)

E. Donovan G. Rostoker C. Y. Huang

We point out a disturbing feature of the Tsyganenko (1989) model magnetic field, namely the occurrence of negative Bz in the model neutral sheet. On the basis of observations of Bz in the neutral sheet we conclude that this is an artifact of the model and not a real effect. This feature of the model should be considered when the model is used either to infer mappings from the ionosphere to the vicinity of the neutral sheet or as a tool in theoretical studies. We propose that in the development of future models, it would be useful for the distribution of Bz in the neutral sheet to be imposed as a constraint on the model.

Current sheet

Feature (linguistics)

Plasma sheet

10.1029/91ja03019

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Citations (15)

The characteristics and world-wide propogation of PI 2 micropulsations

G. Rostoker

10.14288/1.0053370

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Citations (0)

Automated Forward Modelling and its Results for Substorms and Sawtooth Events

Martin Connors G. Rostoker R. L. McPherron Tung‐Shin Hsu Jason Ponto

Sawtooth wave

Source

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Dependence of Pc5 micropulsation power on conductivity variations in the morning sector

Planetary and Space Science (1979)

P. Sutcliffe G. Rostoker

Electrojet

Noon

Local time

Electron precipitation

10.1016/0032-0633(79)90160-0

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Citations (14)

Influence of Shock-Induced Ionospheric Conductivity Enhancements on Storm Main Phase Intensities

B. Tsurutani X. Zhou J. K. Arballo D. Winterhalter Tohru Araki

Source

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Citations (0)

Radial dependence of relativistic electron fluxes for storm main phase development

Journal of Geophysical Research Atmospheres (2002)

H.‐J. Kim G. Rostoker Y. Kamide

Satellite observations have revealed that the flux variations of outer belt relativistic electrons during the main phase of a magnetic storm exhibit a strong radial dependence. This L dependence is characterized as a small increase or decrease near the inner edge of the belt ( L ∼ 3) and a large decrease inits outer region ( L ∼ 5). Extending the study by Kim and Chan [1997] of relativistic electron flux decreases at geostationary orbit, we investigate the characteristic radial dependence in terms of the fully adiabatic response of relativistic electrons to magnetic field perturbations. Using Liouville's theorem and the conservation of the first and third adiabatic invariants, we calculate storm main phase fluxes of equatorially mirroring electrons by adiabatically evolving the prestorm values. A quiet time electron distribution model is constructed from the CRRES satellite data. The radial structure of magnetic field perturbations and the spatial and energy dependence of the quiet time electron distribution are found to affect the main phase fluxes through adiabatic processes. In response to the field perturbations, adiabatic flux changes become larger at higher L shells where electrons can experience strong deceleration and considerable radial displacement. The nonmonotonic energy spectrum at the inner edge of the outer belt, which is featured in our quiet time electron model, can yield a slight flux increase in that region even during adiabatic deceleration. The results of this study suggest that a fully adiabatic treatment can provide an important component of the explanation for the general pattern of large scale changes in the radial profile of relativistic electron fluxes during the storm main phase.

Van Allen Probes

10.1029/2001ja007513

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Citations (8)

A relationship between synchronous altitude electron fluxes and the auroral electrojet

Journal of Geophysical Research Atmospheres (1975)

R. D. Sharp E. G. Shelley G. Rostoker

Simultaneous observations during four substorms are reported from the Lockheed auroral particle spectrometer on ATS 5 and the University of Alberta meridian magnetometer chain. During the four events studied there was a good correlation between the magnitude of the trapped electron fluxes in the energy range from 1.8 to 53 keV and the magnitude of the electrojet current as measured by a station in the magnetometer chain at a latitude close to that expected for the ATS conjugate point. A model electrojet is constructed based on the work of Coroniti and Kennel (1972) which gives a good absolute agreement between the two measured quantities. The results are consistent with the convection electric field's remaining approximately constant during a substantial portion of each of the substorms studied. The temporal variations of the electrojet were apparently controlled by conductivity changes in the ionosphere as determined by the precipitating auroral electrons.

Electrojet

Equatorial electrojet

10.1029/ja080i016p02319

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Citations (9)

Satellite anomalies linked to electron increase in the magnetosphere

Eos (1994)

D. N. Baker S. G. Kanekal J. B. Blake B. Klecker G. Rostoker

On January 20, 1994, at 1443 UT, the momentum wheel control circuitry of the Intelsat K spacecraft at geostationary orbit suffered an operational anomaly causing a loss of attitude control. The system was switched to the backup circuitry, and control was reestablished. The same day, at 1735 UT, the Anik E‐l spacecraft, also at geostationary orbit, suffered the same kind of operational anomaly in the momentum wheel control circuitry [ Rostoker , 1994]. According to newspaper accounts the next day, Telesat Canada operators struggled for 8 hours to regain control of the Anik E‐1 satellite. They were able to finally switch to the backup momentum wheel controller and resume reasonably normal operations.

Momentum (technical analysis)

Anomaly (physics)

Orbit (dynamics)

10.1029/94eo01038

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Citations (112)

Coordinated ISTP satellite and ground observations of morningside Pc5 waves

Journal of Geophysical Research Atmospheres (1999)

S. Ohtani G. Rostoker Kazue Takahashi V. Angelopoulos Masato Nakamura

This paper reports the result of a coordinated data analysis of a morningside Pc 5 event observed at different altitudes in the magnetosphere and also on the ground. The event took place during 1400–1500 UT of April 29, 1993. The Geotail satellite was located in the boundary region and observed a 5‐min quasi‐periodic magnetic oscillation. The oscillation was mostly transverse to the background magnetic field. A 90° phase lag between the magnetic field and electric field variations was not clear, suggesting that the oscillation was not a standing wave and that Geotail was located in or close to the excitation region. The plasma flow vector rotated clockwise on the equatorial plane viewed from the north as expected for a magnetospheric surface wave on the morningside. At geosynchronous altitude, the GOES satellites also observed a 5‐min magnetic oscillation but with a significantly smaller amplitude than at the Geotail position. Five‐minute magnetic oscillations were also detected at Canadian Auroral Network for the OPEN Program Unified Study (CANOPUS) and Magnetometer Array for Cusp and Cleft Studies (MACCS) ground stations in the same local time sector as the satellites, even equatorward of a region 2 field‐aligned current observed by the Freja magnetometer data. From the phase analysis of ground signatures, the wave is inferred to propagate westward (antisunward) at a velocity of 18° in longitude per minute. The propagation speed mapped to the equator, 400 km/s, is in the range of the expected flow speed of the magnetosheath. It is inferred that in the present event, the Kelvin‐Helmholtz instability at the magnetopause, rather than at the inner edge of the boundary layer, excited an oscillation at the single frequency in a large area from the boundary region to deep inside the magnetosphere.

Substorm

Oscillation (cell signaling)

Local time

Electrojet

Magnetosheath

Longitude

10.1029/1998ja900037

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Citations (13)