Search Publications
Anisotropy of the Taylor scale and the correlation scale in plasma sheet magnetic field fluctuations as a function of auroral electrojet activity
El-Alaoui, M.; Dasso, S.; Matthaeus, W. H. +2 more
Magnetic field data from the Cluster spacecraft in the magnetospheric plasma sheet are employed to determine the correlation scale and the magnetic Taylor microscale from simultaneous multiple-point measurements for multiple intervals over a range of mean magnetic field directions for three different levels of geomagnetic activity. We have determi…
Moderate geomagnetic storm (21-22 January 2005) triggered by an outstanding coronal mass ejection viewed via energetic neutral atoms
Barabash, Stas; McKenna-Lawlor, Susan; Dandouras, Iannis +7 more
An outstanding flare on 20 January 2005 was accompanied by a coronal mass ejection which arrived at the magnetopause at ∼1712 UT, 21 January, and produced a strong compression-pressure pulse. Enhanced magnetospheric activity was stimulated. The associated development between <1800 UT and >02.19 UT on 21-22 January, 2005 of a ring current dis…
Whistler propagation and modulation in the presence of nonlinear Alfvén waves
Goldstein, M. L.; Sharma, R. P.; Dwivedi, Navin Kumar +1 more
This paper presents the modulation of whistler waves due to linear interactions between a weak whistler signal and a pump kinetic Alfvén wave (KAW) in intermediate-β(me/mi ≪ β ≪ 1) plasmas (where β is the ratio of the ion sound speed to the Alfvén speed). As a consequence of ponderomotive nonlinearity, the pump KAW becomes fi…
Venusian bow shock as seen by the ASPERA-4 ion instrument on Venus Express
Coates, A. J.; Kallio, E.; Schmidt, W. +40 more
The Analyzer of Space Plasmas and Energetic Atoms (ASPERA-4) instrument on Venus Express is used to determine bow shock position at Venus using ion data alone, using data recorded during a solar minimum from the Ion Mass Analyzer (IMA) which is part of the ASPERA-4 package. Previous models constructed from solar minimum data using Venus Express, P…
Recovery of time evolution of Grad-Shafranov equilibria from single-spacecraft data: Benchmarking and application to a flux transfer event
Hasegawa, Hiroshi; Sonnerup, Bengt U. Ã. -.; Nakamura, Takuma K. M.
First results are presented of a method, developed by Sonnerup and Hasegawa (2010), for analyzing time evolution of magnetohydrostatic Grad-Shafranov (GS) equilibria, using data recorded by an observing probe as it traverses a quasi-static, two-dimensional (2D), magnetic-field/plasma structure. The method recovers spatial initial values used in th…
Energetic electron microsignatures as tracers of radial flows and dynamics in Saturn's innermost magnetosphere
Coates, A. J.; Krupp, N.; Roussos, E. +6 more
Signatures of energetic electron depletions from Saturn's inner moons (microsignatures) have been mainly utilized to infer properties of magnetospheric diffusion. The same data, however, indicate that microsignatures can be a much more powerful tool for magnetospheric studies. Here we introduce a new method where the energy structure of a microsig…
Harmonic growth of ion-cyclotron waves in Saturn's magnetosphere
Russell, C. T.; Dougherty, M. K.; Wilson, R. J. +3 more
Ion-cyclotron waves have been observed by the Cassini spacecraft in Saturn's middle magnetosphere. Waves have frequencies near the gyrofrequencies of water-group ions, they are left handed, and in most regions they propagate at small angles to the ambient magnetic field. Their origin is explained in terms of the ion-cyclotron instability generated…
On slowly evolving Grad-Shafranov equilibria
Hasegawa, Hiroshi; Sonnerup, Bengt U. Ã. -.
A method is developed for analyzing the slow, purely kinematic evolution of magnetohydrostatic Grad-Shafranov equilibria, recovered by reconstruction from data taken by a single spacecraft as it traverses a quasi-static, two-dimensional, magnetic field/plasma structure in space, such as a flux transfer event at the magnetopause. The evolution is c…
Hybrid simulations of the plasma environment around Enceladus
Russell, C. T.; Tokar, R. L.; Leisner, J. S. +1 more
The plasma environment around Enceladus is governed by the interaction between the corotating plasma with the body of the moon and the neutral gas associated with Saturn's extended cloud and plumes ejected from its southern polar region. To understand the nature of this interaction, we use 3-D electromagnetic hybrid simulations that treat ions kin…
Chorus wave generation near the dawnside magnetopause due to drift shell splitting of substorm-injected electrons
Keika, Kunihiro; Lee, Jeongwoo; Min, Kyungguk
We study the relationship between the electron injection and the chorus waves during a substorm event on 23 March 2007. The chorus waves were detected at high geomagnetic latitude (∼70°S) Antarctic observatories in the range of 0600-0900 h in magnetic local time (MLT). Electrons drifting from the injection event were measured by two LANL spacecraf…