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Orientation, location, and velocity of Saturn's bow shock: Initial results from the Cassini spacecraft
Russell, C. T.; Dougherty, M. K.; Tsurutani, B. T. +8 more
The Cassini spacecraft commenced its tour of the planet Saturn on 1 July 2004 (GMT). During the insertion orbit, the Cassini magnetometer (MAG), radio/plasma wave experiment (RPWS), and plasma spectrometer (CAPS) obtained in situ measurements of the magnetic field and plasma conditions associated with Saturn's environment. Analysis of the magnetic…
Ripples observed on the surface of the Earth's quasi-perpendicular bow shock
Horbury, T. S.; Lucek, E. A.; Burgess, D. +1 more
Multipoint measurements from Cluster of a particularly slow encounter with the Earth's bow shock are presented. The shock is classified as high Mach number, quasi-perpendicular, and high plasma beta. Coherent oscillations of the plasma density and the magnetic field amplitude are seen in the foot and ramp of the shock with period approximately 15 …
Orientation and motion of a plasma discontinuity from single-spacecraft measurements: Generic residue analysis of Cluster data
Balogh, A.; RèMe, H.; Dunlop, M. W. +3 more
A unified minimum-residue approach is presented to the use of classical conservation laws for determination of the orientation and motion of a plasma discontinuity, using data from a single spacecraft that traverses the discontinuity and makes measurements, not only on its two sides but also within it. The method is a generalization of the minimum…
Saturn's auroral morphology and activity during quiet magnetospheric conditions
Coates, A. J.; Dougherty, M. K.; Kurth, W. S. +8 more
We report the results of a coordinated Hubble Space Telescope-Cassini campaign that took place between 26 October and 2 November 2005. During this period, Saturn's magnetosphere was in an expanded state and the solar wind was quiet, as indicated by the location of the magnetopause, in situ particle measurements, weak auroral SKR emission, and the …
Striated auroral kilometric radiation emission: A remote tracer of ion solitary structures
Gurnett, D. A.; Menietti, J. D.; Mutel, R. L. +2 more
We describe the statistical properties of narrowband drifting auroral kilometric radiation ("striated" AKR) based on observations from the Cluster wideband receiver during 2002-2005. We show that the observed characteristics, including frequency drift rate and direction, narrow bandwidth, observed intensity, and beaming angular sizes are all consi…
Magnetospheric energy budget during huge geomagnetic activity using Cluster and ground-based data
Buchert, S.; Vaivads, A.; Lu, G. +2 more
The Cluster spacecraft crossed the magnetopause at the duskward flank of the tail while the European Incoherent Scatter (EISCAT) radars and magnetometers observed the ionosphere during a sequence of intense substorm-like geomagnetic activity in October 2003. We attempt to estimate the local and global energy flow from the magnetosheath into the ma…
Are halo coronal mass ejections special events?
Gopalswamy, Nat; Xie, Hong; Lara, Alejandro +3 more
We revisited the properties of wide coronal mass ejections (CMEs) called halo CMEs. Using the large LASCO/SOHO CMEs data set, from 1996 to 2004, we examined the statistical properties of (partial and full) halo CMEs and compare with the same properties of "normal" width (lower than 120°) CMEs. We found that halo CMEs have different properties than…
Divergent electric fields in downward current channels
Streltsov, A. V.; Marklund, G. T.
The results from a numerical study on the formation and dynamics of the localized, diverging perpendicular electric fields found in the nightside auroral magnetosphere are presented. These fields are frequently observed inside the downward magnetic field-aligned current (FAC) channels where the electrons flow upward from the ionosphere. The presen…
The 17-22 October (1999) solar-interplanetary-geomagnetic event: Very intense geomagnetic storm associated with a pressure balance between interplanetary coronal mass ejection and a high-speed stream
Balmaceda, Laura A.; Dal Lago, Alisson; Gonzalez, Walter D. +9 more
Using observations from the Advanced Composition Explorer (ACE) magnetic field and plasma experiments, we investigate the magnetic, thermal, and dynamic pressure balance in the border of a high-speed stream (HSS) and an average-speed interplanetary coronal mass ejection (ICME) observed on 21-22 October (1999). We believe that the HSS compressed th…
Bifurcated current sheets: Statistics from Cluster magnetometer measurements
Balogh, A.; Kistler, L. M.; El-Alaoui, M. +3 more
We report on a statistical study of bifurcated current sheets in the near-Earth plasma sheet and the association of such current sheets with a near-Earth neutral line. Support for this interpretation is provided by a global MHD simulation generated for geomagnetic and solar wind conditions prevailing at the time when a bifurcated current sheet was…