Search Publications
Global reconnection topology as inferred from plasma observations inside Kelvin-Helmholtz vortices
Dandouras, I.; Lucek, E.; Kistler, L. M. +4 more
During a long lasting period of northward interplanetary magnetic field and high solar wind speed (above 700 km/s), the Cluster spacecraft go across a number of very large rolled-up Kelvin-Helmholtz (KH) vortices at the dusk magnetopause, close to the terminator. The peculiarity of the present event is a particular sequence of ions and electrons d…
Large-scale fluctuations of PSBL magnetic flux tubes induced by the field-aligned motion of highly accelerated ions
Zelenyi, L. M.; Sauvaud, J. -A.; Grigorenko, E. E. +2 more
We present a comprehensive analysis of magnetic field and plasma data measured in the course of 170 crossings of the lobeward edge of Plasma Sheet Boundary Layer (PSBL) in the Earth's magnetotail by Cluster spacecraft. We found that large-scale fluctuations of the magnetic flux tubes have been registered during intervals of propagation of high vel…
On arc-polarized structures in the solar wind
Haaland, S. E.; Paschmann, G.; Sonnerup, B. U. Ö.
A theoretical model is proposed to account for some of the behavior of arc-polarized magnetic structures seen in the solar wind. To this end, an exact analytical solution is developed that describes infinite plane wave trains of arbitrary amplitude in a plasma governed by ideal Hall MHD. The main focus is on intermediate-mode wave trains, which di…
Auroral and sub-auroral phenomena: an electrostatic picture
de Keyser, J.; Echim, M.
Many auroral and sub-auroral phenomena are manifestations of an underlying magnetosphere-ionosphere coupling. In the electrostatic perspective the associated auroral current circuit describes how the generator (often in the magnetosphere) is connected to the load (often in the ionosphere) through field-aligned currents. The present paper examines …
Monopolar and bipolar auroral electric fields and their effects
de Keyser, J.; Maggiolo, R.; Echim, M.
Most of the high-altitude auroral electric fields observed by CLUSTER can be classified into monopolar and bipolar structures. The observations associate monopolar electric fields with polar cap boundary arcs, while bipolar fields tend to be linked to discrete arcs within the auroral oval and to polar cap arcs. The present paper proposes an explan…
Effects of a solar wind dynamic pressure increase in the magnetosphere and in the ionosphere
Milan, S. E.; Kauristie, K.; Amm, O. +4 more
On 17 July 2005, an earthward bound north-south oriented magnetic cloud and its sheath were observed by the ACE, SoHO, and Wind solar wind monitors. A steplike increase of the solar wind dynamic pressure during northward interplanetary magnetic field conditions was related to the leading edge of the sheath. A timing analysis between the three spac…
The Alfvén edge in asymmetric reconnection
André, M.; Vaivads, A.; Khotyaintsev, Yu. V. +1 more
We show that in the case of magnetic reconnection where the Alfvén velocity is much higher in the plasma on one side of the current sheet than the other, an Alfvén edge is formed. This edge is located between the electron and ion edges on the high Alfvén velocity side of the current sheet. The Alfvén edge forms because the Alfvén wave generated ne…
Local influence of magnetosheath plasma beta fluctuations on magnetopause reconnection
André, M.; Vaivads, A.; Rème, H. +2 more
We present observations from two subsolar Cluster magnetopause crossings under southward interplanetary magnetic field and strong mirror mode fluctuations in the magnetosheath. In both events the reconnection outflow jets show strong variations on the timescale of one minute. We show that at least some of the recorded variations are truly temporal…
First measurements of electron vorticity in the foreshock and solar wind
Fazakerley, A. N.; Gurgiolo, C.; Goldstein, M. L. +1 more
We describe the methodology used to set up and compute spatial derivatives of the electron moments using data acquired by the Plasma Electron And Current Experiment (PEACE) from the four Cluster spacecraft. The results are used to investigate electron vorticity in the foreshock. We find that much of the measured vorticity, under nominal conditions…
Oxygen ion energization observed at high altitudes
Gunell, H.; Waara, M.; Nilsson, H. +3 more
We present a case study of significant heating (up to 8 keV) perpendicular to the geomagnetic field of outflowing oxygen ions at high altitude (12 RE) above the polar cap. The shape of the distribution functions indicates that most of the heating occurs locally (within 0.2-0.4 RE in altitude). This is a clear example of local…