Search Publications
Motion of observed structures calculated from multi-point magnetic field measurements: Application to Cluster
Balogh, A.; Zong, Q. -G.; Lucek, E. +5 more
A new method is described which calculates the velocity of observed, quasi-stationary structures at every moment in time from multi-point magnetic field measurements. Once the magnetic gradient tensor G = $\nabla$$\vec {B and the time variation of the magnetic field have been estimated at every moment, the velocity can then be determined, in princ…
Structure of the separatrix region close to a magnetic reconnection X-line: Cluster observations
Pickett, J. S.; André, M.; Khotyaintsev, Y. +9 more
We use Cluster spacecraft observations to study in detail the structure of a magnetic reconnection separatrix region on the magnetospheric side of the magnetopause about 50 ion inertial lengths away from the X-line. The separatrix region is the region between the magnetic separatrix and the reconnection jet. It is several ion inertial lengths wide…
Do BBFs contribute to inner magnetosphere dipolarizations: Concurrent Cluster and Double Star observations
Zhang, T. L.; Klecker, B.; Nakamura, R. +7 more
We examined the relationship between bursty bulk flow (BBF) events observed by Cluster between -19 RE < X < -12 RE and dipolarization events observed by Double Star TC1 between -13 RE < X < -6 RE. TC1 observed dipolarizations for ~33% of the cases when BBFs were observed by Cluster. During th…
Low-energy (order 10 eV) ion flow in the magnetotail lobes inferred from spacecraft wake observations
Dandouras, I.; André, M.; Quinn, J. +4 more
Cold ionospheric ions with eV energies are common in the magnetosphere and can travel far out in the magnetotail. However, they are difficult to measure with conventional ion spectrometers mounted on spacecraft, since the potential of a sunlit spacecraft often reaches several tens of volts. In this paper we present two alternative methods of measu…
Substorm associated magnetotail energetic electrons pitch angle evolutions and flow reversals: Cluster observation
Lucek, E.; Fritz, T. A.; Wu, P. +1 more
The Cluster satellites observed a distinct pattern in the evolution of energetic electron pitch angle distributions on November 13, 2003, in the mid-tail (radius >10RE) associated with intensifications of these electron fluxes that accompanied an observed local dipolarization of the magnetic field. The intensity of electrons (20-200 …
Cluster PEACE observations of electron pressure tensor divergence in the magnetotail
Lucek, E.; Fazakerley, A. N.; Owen, C. J. +4 more
Cluster crossed the magnetotail neutral sheet on four occasions between 16:38 and 16:43 UT on 08/17/2003. The four-spacecraft capabilities of Cluster are used to determine spatial gradients from the magnetic field vectors and, for the first time, full electron pressure tensors. We find that the contribution to the electric field from the Hall term…
Kinetic aspects of foreshock cavities
Schwartz, Steven J.; Meziane, Karim; Horbury, Timothy S. +2 more
We have investigated the kinetic signatures within, and at the edges of, a foreshock cavity. Such cavities are believed to be formed when an isolated collection of interplanetary magnetic field lines connect to quasi-parallel regions of the Earth's bow shock, allowing energetic ions to flow upstream and excavate a local cavity. Observations by the…
Temporal evolution of a staircase ion signature observed by Cluster in the mid-altitude polar cusp
Berchem, J.; Escoubet, C. P.; Pitout, F. +9 more
We use the Cluster string of pearls configuration to investigate temporal variations of ion precipitation in the mid-altitude polar cusp. On 7 Aug. 2004, Cluster 4 was moving poleward through the Northern cusp, followed by Cluster 1, Cluster 2, and finally Cluster 3. The Wind spacecraft detected a Southward turning of the Interplanetary Magnetic F…
Cluster observations of broadband electromagnetic waves in and around a reconnection region in the Earth's magnetotail current sheet
Walsh, A. P.; Freeman, M. P.; Petkaki, P.
We present an analysis of the electric and magnetic wave spectra on kinetic scales during several crossings of a reconnecting current sheet. The spectra were measured from 1 Hz or less up to 4096 Hz by the EFW, FGM and STAFF instruments onboard the Cluster spacecraft between 3 and 4 UT on 11 October 2001. During the event plasma flows of order of …
Spatial gradients in the plasmasphere from Cluster
Dunlop, M. W.; Décréau, P. M. E.; De Keyser, J. +2 more
The Cluster mission allows the study of the plasmasphere with four-point measurements, including its overall density distribution, plasmaspheric plumes close to the plasmapause, and density irregularities inside the plasmasphere. The purpose of this letter is to examine the geometry and orientation of the overall density structure and of the magne…