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The radial width of a Coronal Mass Ejection between 0.1 and 0.4 AU estimated from the Heliospheric Imager on STEREO
Harrison, R. A.; Davies, J. A.; Owens, M. J. +4 more
On 15-17 February 2008, a CME with an approximately circular cross section was tracked through successive images obtained by the Heliospheric Imager (HI) instrument onboard the STEREO-A spacecraft. Reasoning that an idealised flux rope is cylindrical in shape with a circular cross-section, best fit circles are used to determine the radial width of…
First simultaneous measurements of waves generated at the bow shock in the solar wind, the magnetosphere and on the ground
Lucek, E. A.; Yeoman, T. K.; Fear, R. C. +3 more
On 5 September 2002 the Geotail satellite observed the cone angle of the Interplanetary Magnetic Field (IMF) change to values below 30° during a 56 min interval between 18:14 and 19:10 UT. This triggered the generation of upstream waves at the bow shock, 13 RE downstream of the position of Geotail. Upstream generated waves were subseque…
Separatrix regions of magnetic reconnection at the magnetopause
Lavraud, B.; André, M.; Vaivads, A. +5 more
Using data from the four Cluster spacecraft we study the separatrix regions of magnetic reconnection sites at the dayside magnetopause under conditions when reconnection is occurring in the magnetopause current layer which separates magnetosheath plasma from the hot magnetospheric plasma sheet. We define the separatrix region as the region between…
Analysis of three-spacecraft data using planar reciprocal vectors: methodological framework and spatial gradient estimation
Marghitu, O.; Albert, A.; Vogt, J.
In the context of ESA's Cluster mission, four-point array techniques are widely used to analyze space plasma phenomena such as shocks and discontinuities, waves and turbulence, and spatial gradients. Due to failures of single instruments on the Cluster spacecraft fleet, there is also need for array processing of three-point measurements. In this p…
Dipole tilt effects in plasma sheet By: statistical model and extreme values
Petrukovich, A. A.
With 11 years of Geotail measurements we construct a model of plasma sheet By, depending on IMF By, coordinates X,Y and geodipole tilt angle. At midnight and pre-midnight local times By is positively correlated with tilt (positive in summer). Thus in summer By is shifted towards positive values and in wi…
Solar wind and substorm excitation of the wavy current sheet
Dandouras, I.; Lucek, E.; Fazakerley, A. N. +5 more
Following a solar wind pressure pulse on 3 August 2001, GOES 8, GOES 10, Cluster and Polar observed dipolarizations of the magnetic field, accompanied by an eastward expansion of the aurora observed by IMAGE, indicating the occurrence of two substorms. Prior to the first substorm, the motion of the plasma sheet with respect to Cluster was in the Z…
Multi-spacecraft measurement of anisotropic power levels and scaling in solar wind turbulence
Horbury, T. S.; Osman, K. T.
Measurements by the four Cluster spacecraft in the solar wind are used to determine quantitatively the field-aligned anisotropy of magnetohydrodynamic inertial range turbulence power levels and spectral indexes. We find, using time-lagged second order structure functions, that the spectral index is near 2 around the field-parallel direction, which…
Cluster and ACE observations of phase synchronization in intermittent magnetic field turbulence: a comparative study of shocked and unshocked solar wind
Chian, A. C. -L.; Miranda, R. A.
We apply two distinct nonlinear techniques, kurtosis and phase coherence index, to analyze the modulus of interplanetary magnetic field data |B| measured by Cluster and ACE spacecraft from 1 to 3 February 2002. High degree of phase synchronization is found across a wide range of time scales, from 1 s to 104 s, in the magnetic field fluc…
Signatures of interchange reconnection: STEREO, ACE and Hinode observations combined
Sauvaud, J. -A.; Luhmann, J. G.; van Driel-Gesztelyi, L. +8 more
Combining STEREO, ACE and Hinode observations has presented an opportunity to follow a filament eruption and coronal mass ejection (CME) on 17 October 2007 from an active region (AR) inside a coronal hole (CH) into the heliosphere. This particular combination of "open" and closed magnetic topologies provides an ideal scenario for interchange recon…
Oxygen ion escape from Venus in a global hybrid simulation: role of the ionospheric O+ ions
Kallio, E.; Janhunen, P.; Barabash, S. +4 more
We study the solar wind induced oxygen ion escape from Venus' upper atmosphere and the Venus Express observations of the Venus-solar wind interaction by the HYB-Venus hybrid simulation code. We compare the simulation to the magnetic field and ion observations during an orbit of nominal upstream conditions. Further, we study the response of the ind…