Magnetospheric substorms observed at the synchronous orbit

Cummings, W. D.; Barfield, J. N.; Coleman, Paul J.

doi:10.1029/ja073i021p06687

Cited by 181 publications

(77 citation statements)

References 21 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…As is well known (Cummings, at al, 1968;Fairfield and Ness 1970;Coleman and Mc pherron, 1970;Camidge and Rostoker, 1970;Russell at at, 1971) and as is illustrated in Figure 2, the magnetic field in the equatorial plane at -6R e often becomes tail-like during an -1 hour period before the expansion phase and becomes dipole-like during the expansion phase. These facts may be interpreted as evidence of enhanced convection during the growth phase since such convection brings the tail-like magnetic field geometry closer to the earth.…”

mentioning

confidence: 88%

On the relationship between the growth and expansion phases of substorms and magnetospheric convection

Mozer¹

1973

J. Geophys. Res.

View full text Add to dashboard Cite

mentioning

confidence: 88%

On the relationship between the growth and expansion phases of substorms and magnetospheric convection

Mozer¹

1973

J. Geophys. Res.

View full text Add to dashboard Cite

“…Belian, 1978). Cummings et al (1968) showed that during the two substorms they examined, the H component of the magnetic field was decreased and the inclination was radially outward in the dusk-to-midnight quadrant. However, the distortion of the magnetic field was not observed in other local time sectors.…”

Section: Introductionmentioning

confidence: 99%

A statistical study of magnetic dipolarization for sawtooth events and isolated substorms at geosynchronous orbit with GOES data

2006

View full text Add to dashboard Cite

Abstract. We investigate whether the dipolarization process during sawtooth events is global or not through an examination of the local time distribution of the magnetic tilt angle (i.e. the angle between the B vector and the equatorial plane in dipole VDH coordinates) at geostationary orbit. From the statistical analysis of 207 individual teeth and 212 isolated substorms, we find that individual teeth follow a dipolarization pattern similar to that observed for isolated substorms. The dipolarization for individual teeth initiates in the sector between 22:00 magnetic local time (MLT) and 00:00 MLT. Then the dipolarization expands both eastward and westward. However, relative to isolated substorms, we find that the nightside magnetosphere is much more stretched prior to the onset, and the change of the tilt angle during the dipolarization process is much larger during individual teeth. The magnetic dipolarization is seen over a wider local time sector during individual teeth than during isolated substorms. However, the magnetic dipolarization is rarely observed near local noon during individual teeth. This suggests that the magnetic dipolarization process during individual teeth is still confined primarily to the nightside.

show abstract

“…The associated dipolarization of the magnetic field that occurs at substorm onset has been well documented (e.g. Cummings et al, 1968;Kokubun and McPherron, 1981). In the near-Earth magnetotail the formation of a neutral line during substorms is inferred from observations of fast flows forming bursty-bulk flows (BBFs) (e.g.…”

Section: Introductionmentioning

confidence: 99%

Thinning and expansion of the substorm plasma sheet: Cluster PEACE timing analysis

et al. 2004

View full text Add to dashboard Cite

Abstract. The storage and subsequent removal of magnetic flux in the magnetotail during a geomagnetic substorm has a dramatic effect on the thickness of the cross-tail plasma sheet. The near-Earth plasma sheet is thought to thin during the growth phase and then rapidly expand after onset of the substorm. The direction of propagation, whether earthward or tailward along the GSM-X direction in the near-Earth tail, may suggest the time ordering of current-disruption and near-Earth reconnection, both of which are key to the substorm process. Cluster's Plasma Electron And Current Experiment (PEACE) allows 4-point observations of electrons at the plasma sheet -lobe boundary as this interface passes over the Cluster tetrahedron. The relative timings of the boundary passage at each spacecraft allow a determination of this boundary's speed and direction of motion, assuming this is planar on the scale of the Cluster separation scale. For those boundaries corresponding to the expansion of the plasma sheet, this direction is fundamental to determining the direction of expansion. We present an example of isolated thinning and expansion of the plasma sheet, as well as a multiple thinning-expansion event that occurs during a more active substorm. Data from the 2001 and 2002 tail passes have been analysed and the average plasma sheet -lobe boundary normal vectors and normal component velocities have been calculated. A total of 77 crossings, typically between 10 and 20 R E downtail, correspond to substorm associated expansion of the plasma sheet over the spacecraft. These had normal vectors predominantly in the GSM-YZ plane and provided no clear evidence for the formation of the near-Earth neutral line occurring before current disruption or vice versa. The expansions of the plasma sheet generally exhibit the appropriate GSM-Z direction expected for the given lobe, and tend to have GSM-Y components that support onset occurring near the origin of the GSM-YZ plane. This result is noteworthy in that it indicates a homogeneous plasma sheet expansion. These expansions have an average velocity along their normal of 60±37 km s −1 . Conversely we find an average thinning velocity of 43±32 km s −1 from 66 substormCorrespondence to: J. P. Dewhurst (jpd@mssl.ucl.ac.uk) associated thinnings. The normal vectors of the thinning plasma sheet vary considerably in the GSM-YZ plane across the entire magnetotail, suggesting that more complex dynamics govern this process.

show abstract

Magnetospheric substorms observed at the synchronous orbit

Cited by 181 publications

References 21 publications

On the relationship between the growth and expansion phases of substorms and magnetospheric convection

On the relationship between the growth and expansion phases of substorms and magnetospheric convection

A statistical study of magnetic dipolarization for sawtooth events and isolated substorms at geosynchronous orbit with GOES data

Thinning and expansion of the substorm plasma sheet: Cluster PEACE timing analysis

Contact Info

Product

Resources

About