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Electrostatic solitary waves with distinct speeds associated with asymmetric reconnection
André, M.; Vaivads, A.; Khotyaintsev, Yu. V. +1 more
Electrostatic solitary waves (ESWs) are observed at the magnetopause with distinct time scales. These ESWs are associated with asymmetric reconnection of the cold dense magnetosheath plasma with the hot tenuous magnetospheric plasma. The distinct time scales are shown to be due to ESWs moving at distinct speeds and having distinct length scales. T…
Modification of the Hall physics in magnetic reconnection due to cold ions at the Earth's magnetopause
André, M.; Vaivads, A.; Toledo-Redondo, S. +1 more
Magnetic reconnection is a process permitting mass and energy exchange across plasma boundaries and converting magnetic energy into particle kinetic energy. Strong electric fields and currents due to the Hall effect are set up in narrow regions where ions are demagnetized but electrons remain magnetized. It has been recently shown that cold (few e…
Slow electron phase space holes: Magnetotail observations
André, M.; Vaivads, A.; Khotyaintsev, Y. V. +1 more
We report multispacecraft observations of slow electrostatic solitary waves in the plasma sheet boundary layer. The electrostatic solitary waves are embedded in a region with field-aligned electron flows and are interpreted as electron phase space holes. We make unambiguous velocity and length estimates of the electron holes, vEH∼500 km…
Simultaneous field-aligned currents at Swarm and Cluster satellites
Dunlop, M. W.; Carr, C. M.; Bogdanova, Y. V. +13 more
We show for the first time, with direct, multispacecraft calculations of electric current density, and other methods, matched signatures of field-aligned currents (FACs) sampled simultaneously near the ionosphere at low (~500 km altitude) orbit and in the magnetosphere at medium (~2.5 RE altitude) orbits using a particular Swarm and Clu…
Slow electron holes in multicomponent plasmas
André, M.; Vaivads, A.; Khotyaintsev, Yu. V. +2 more
Electrostatic solitary waves (ESWs), often interpreted as electron phase space holes, are commonly observed in plasmas and are manifestations of strongly nonlinear processes. Often slow ESWs are observed, suggesting generation by the Buneman instability. The instability criteria, however, are generally not satisfied. We show how slow electron hole…
Birkeland current effects on high-latitude ground magnetic field perturbations
Anderson, B. J.; Snekvik, K.; Østgaard, N. +8 more
Magnetic perturbations on ground at high latitudes are directly associated only with the divergence-free component of the height-integrated horizontal ionospheric current, J⊥,df. Here we show how J⊥,df can be expressed as the total horizontal current J⊥ minus its curl-free component, the latter being completely det…
Identifying the source region of plasmaspheric hiss
Laakso, Harri; Masson, Arnaud; Escoubet, Philippe +4 more
The presence of the plasmaspheric hiss emission around the Earth has been known for more than 50 years, but its origin has remained unknown in terms of source location and mechanism. The hiss, made of whistler mode waves, exists for most of the time in the plasmasphere and is believed to control the radiation belt surrounding the Earth which makes…
Nonlinear subcyclotron resonance as a formationmechanism for gaps in banded chorus
Gary, S. Peter; Fu, Xiangrong; Dong, Chuanfei +1 more
An interesting characteristic of magnetospheric chorus is the presence of a frequency gap at ω≃0.5Ωe, where Ωe is the electron cyclotron angular frequency. Recent chorus observations sometimes show additional gaps near 0.3Ωe and 0.6Ωe. Here we present a novel nonlinear mechanism for the formation of thes…
Magnetic forces associated with bursty bulk flows in Earth's magnetotail
Karlsson, Tomas; Nilsson, Hans; Hamrin, Maria +2 more
We present the first direct measurements of magnetic forces acting on bursty bulk flow plasma in the magnetotail. The magnetic forces are determined using Cluster multispacecraft measurements. We analyze 67 bursty bulk flow (BBF) events and show that the curvature part of the magnetic force is consistently positive, acting to accelerate the plasma…
Motion of reconnection region in the Earth's magnetotail
Nakamura, Rumi; Semenov, Vladimir S.; Nakamura, Takuma K. M. +1 more
We obtain the X-line velocity in the Earth's magnetotail for 24 reconnection events observed by the Cluster spacecraft between 2001 and 2005. The data set consists of 10 single X-lines and 14 X-lines from the time intervals of multiple reconnection. Except for two X-lines from multiple reconnection, all the X-lines move tailward (radial outward) a…