Search Publications
Deriving the radial distances of wide coronal mass ejections from elongation measurements in the heliosphere - application to CME-CME interaction
Vourlidas, A.; Lugaz, N.; Roussev, I. I.
We present general considerations regarding the derivation of the radial distances of coronal mass ejections (CMEs) from elongation angle measurements such as those provided by SECCHI and SMEI, focusing on measurements in the Heliospheric Imager 2 (HI-2) field of view (i.e. past 0.3 AU). This study is based on a three-dimensional (3-D) magneto-hyd…
Evolution of dipolarization in the near-Earth current sheet induced by Earthward rapid flux transport
Dandouras, I.; André, M.; Klecker, B. +7 more
We report on the evolution of dipolarization and associated disturbances of the near-Earth current sheet during a substorm on 27 October 2007, based upon Cluster multi-point, multi-scale observations of the night-side plasma sheet at X~-10 RE. Three dipolarization events were observed accompanied by activations on ground magnetograms at…
Survey of cold ionospheric outflows in the magnetotail
André, M.; Eriksson, A. I.; Cully, C. M. +4 more
Low-energy ions escape from the ionosphere and constitute a large part of the magnetospheric content, especially in the geomagnetic tail lobes. However, they are normally invisible to spacecraft measurements, since the potential of a sunlit spacecraft in a tenuous plasma in many cases exceeds the energy-per-charge of the ions, and little is theref…
Plasma boundary variability at Mars as observed by Mars Global Surveyor and Mars Express
Barabash, S.; Fränz, M.; Lester, M. +4 more
We have used Mars Express (MEX) and Mars Global Surveyor (MGS) simultaneous and non-simultaneous measurements to study the Martian plasma environment. In particular, we have derived quantitative expressions for the altitude of the terminator bow shock (BS) and magnetic pileup boundary (MPB) as functions of solar wind dynamic pressure, crustal magn…
Mirror structures above and below the linear instability threshold: Cluster observations, fluid model and hybrid simulations
Budnik, E.; Dandouras, I.; Génot, V. +6 more
Using 5 years of Cluster data, we present a detailed statistical analysis of magnetic fluctuations associated with mirror structures in the magnetosheath. We especially focus on the shape of these fluctuations which, in addition to quasi-sinusoidal forms, also display deep holes and high peaks. The occurrence frequency and the most probable locati…
Thin embedded current sheets: Cluster observations of ion kinetic structure and analytical models
Malova, H. V.; Petrukovich, A. A.; Zelenyi, L. M. +3 more
Kinetic structure of embedded thin horizontal current sheets is investigated. Current density estimated by curlometer technique is in general agreement with a sum of electron and proton currents. Embedding of observed thin current sheets in the much wider plasma sheet is apparent in the current density profiles. Ion velocity distributions consist …
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 …