Search Publications
On the numerical modelling of VLF chorus dynamical spectra
Santolik, O.; Nunn, D.; Rycroft, M. +1 more
This paper presents a study of the use of a one-dimensional Vlasov Hybrid Simulation (VHS) computer code to simulate the dynamical spectra (i.e. frequency versus time spectrograms) of ELF/VLF chorus signals (from ~a fraction to ~10 kHz). Recently excellent measurements of chorus have been made in the source region close to the geomagnetic equator …
A global study of hot flow anomalies using Cluster multi-spacecraft measurements
Dandouras, I.; Facskó, G.; Erdos, G. +2 more
Hot flow anomalies (HFAs) are studied using observations of the magnetometer and the plasma instrument aboard the four Cluster spacecraft. We study several specific features of tangential discontinuities on the basis of Cluster measurements from the time periods of February-April 2003, December 2005-April 2006 and January-April 2007, when the sepa…
Low frequency eigenmodes of thin anisotropic current sheets and Cluster observations
Malova, H. V.; Petrukovich, A. A.; Zelenyi, L. M. +3 more
The eigenmodes of low frequency perturbations of thin anisotropic current sheets with a finite value of the normal magnetic field, are investigated in this paper. It is shown that two possible polarizations of symmetric and asymmetric modes (sausage and kink) exist where the growth rate of instabilities is positive. In addition, we demonstrate tha…
Cluster and Double Star multipoint observations of a plasma bubble
Zhang, T. L.; Dandouras, I.; Lucek, E. +14 more
Depleted flux tubes, or plasma bubbles, are one possible explanation of bursty bulk flows, which are transient high speed flows thought to be responsible for a large proportion of flux transport in the magnetotail. Here we report observations of one such plasma bubble, made by the four Cluster spacecraft and Double Star TC-2 around 14:00 UT on 21 …
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…