Change search
ReferencesLink to record
Permanent link

Direct link
Cluster observations in the inner magnetosphere during the 18 April 2002 sawtooth event: Dipolarization and injection at r=4.6 R-E
KTH, School of Electrical Engineering (EES), Space and Plasma Physics.
Show others and affiliations
2007 (English)In: Journal of Geophysical Research, ISSN 0148-0227, Vol. 112, no A8Article in journal (Refereed) Published
Abstract [en]

The present study examines a sawtooth injection event that took place around 0800 UT on 18 April 2002 when the Cluster spacecraft were located in the inner magnetosphere in the premidnight sector. In association with this injection, Cluster, at a radial distance of 4.6 RE, observed that the local magnetic field became more dipolar and that both ion and electron fluxes increased without notable energy dispersion. These features were accompanied by intensifications of the equatorward component of a double- oval structure and also by an enhancement of the ring- current oxygen ENA flux. The event was also accompanied by large magnetic field ( a few tens of nT) and electric field ( a few tens of mV/ m) fluctuations with characteristic timescales of a few tens of seconds. These observations strongly suggest that this sawtooth injection extended not only widely in local time but also deeply into the inner magnetosphere. Interestingly, Cluster repeatedly observed dipolarization- like signatures afterward, which, however, were not associated with enhancements of local energetic ion flux or with geosynchronous dipolarization or injection signatures. Instead, these magnetic signatures were accompanied by oscillatory plasma motion in the radial direction with a characteristic timescale of about 10 min, which appears to be related to the westward propagation of a spatially periodic auroral structure. The associated azimuthal electric field component was well correlated with the time derivative of the north- south magnetic field component, suggesting that the observed electric field is inductive. These findings suggest that electromagnetic processes far inside geosynchronous orbit play an important role in energization of energetic ions and auroral dynamics during magnetospheric storms.

Place, publisher, year, edition, pages
2007. Vol. 112, no A8
Keyword [en]
storm-substorm relationship, ring current, tail current, geomagnetic storms, electric-field, ampte cce, magnetotail, mission, sheet
URN: urn:nbn:se:kth:diva-16945DOI: 10.1029/2007ja012357ISI: 000249339100002ScopusID: 2-s2.0-35349020509OAI: diva2:334988
QC 20100525Available from: 2010-08-05 Created: 2010-08-05Bibliographically approved

Open Access in DiVA

No full text

Other links

Publisher's full textScopus

Search in DiVA

By author/editor
Blomberg, Lars G.
By organisation
Space and Plasma Physics
In the same journal
Journal of Geophysical Research

Search outside of DiVA

GoogleGoogle Scholar
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

Altmetric score

Total: 25 hits
ReferencesLink to record
Permanent link

Direct link