Search Publications
Ion nose spectral structures observed by the Van Allen Probes
Kistler, L. M.; Zhang, J. -C.; Spence, H. E. +5 more
We present a statistical study of nose-like structures observed in energetic hydrogen, helium, and oxygen ions near the inner edge of the plasma sheet. Nose structures are spectral features named after the characteristic shapes of energy bands or gaps in the energy-time spectrograms of in situ measured ion fluxes. Using 22 months of observations f…
Interactions between magnetosonic waves and ring current protons: Gyroaveraged test particle simulations
Zhang, Hui; Huang, Shiyong; Fu, Song +6 more
Gyroaveraged test particle simulations are implemented to quantitatively investigate interactions between linearly polarized magnetosonic waves (i.e., equatorial noises) and ring current protons inside and outside the plasmasphere at L = 4.5. For magnetosonic waves at the frequency of 33.3 Hz (fw/fcp = 6.4 at the magnetic equ…
Influence of intermittency on the anisotropy of magnetic structure functions of solar wind turbulence
He, Jiansen; Wang, Xin; Wang, Linghua +4 more
Intermittency appears to be connected with the spectral anisotropy of solar wind turbulence. We use the Local Intermittency Measure to identify and remove intermittency from the magnetic field data measured by the Ulysses spacecraft in fast solar wind. Structure functions are calculated based on the time sequences as obtained before and after remo…
Cassini observations of Saturn's southern polar cusp
Coates, A. J.; Krupp, N.; Russell, C. T. +15 more
The magnetospheric cusps are important sites of the coupling of a magnetosphere with the solar wind. The combination of both ground- and space-based observations at Earth has enabled considerable progress to be made in understanding the terrestrial cusp and its role in the coupling of the magnetosphere to the solar wind via the polar magnetosphere…
Conjugate observations of quasiperiodic emissions by the Cluster, Van Allen Probes, and THEMIS spacecraft
Pickett, J. S.; Kurth, W. S.; Santolík, O. +3 more
We present results of a detailed analysis of two electromagnetic wave events observed in the inner magnetosphere at frequencies of a few kilohertz, which exhibit a quasiperiodic (QP) time modulation of the wave intensity. The events were observed by the Cluster and Van Allen Probes spacecraft and in one event also by the THEMIS E spacecraft. The s…
Field-aligned currents in Saturn's magnetosphere: Local time dependence of southern summer currents in the dawn sector between midnight and noon
Coates, A. J.; Dougherty, M. K.; Alexeev, I. I. +6 more
We examine and compare the magnetic field perturbations associated with field-aligned ionosphere-magnetosphere coupling currents at Saturn, observed by the Cassini spacecraft during two sequences of highly inclined orbits in 2006/2007 and 2008 under late southern summer conditions. These sequences explore the southern currents in the dawn-noon and…
First in situ evidence of electron pitch angle scattering due to magnetic field line curvature in the Ion diffusion region
Lavraud, B.; Liu, Z. X.; Rong, Z. J. +8 more
Theory predicts that the first adiabatic invariant of a charged particle may be violated in a region of highly curved field lines, leading to significant pitch angle scattering for particles whose gyroradius are comparable to the radius of the magnetic field line curvature. This scattering generates more isotropic particle distribution functions, …
Commentary on accessing 3-D currents in space: Experiences from Cluster
Dunlop, M. W.; Haaland, S.; Dong, X. -C. +1 more
The curlometer was introduced to estimate the electric current density from four-point measurements in space; anticipating the realization of the four spacecraft Cluster mission which began full science operations in February 2001. The method uses Ampère's law to estimate current from the magnetic field measurements, suitable for the high-conducti…
Characterization of Saturn's bow shock: Magnetic field observations of quasi-perpendicular shocks
Dougherty, M. K.; Masters, A.; Sulaiman, A. H.
Collisionless shocks vary drastically from terrestrial to astrophysical regimes resulting in radically different characteristics. This poses two complexities. First, separating the influences of these parameters on physical mechanisms such as energy dissipation. Second, correlating observations of shock waves over a wide range of each parameter, e…
An induced global magnetic field looping around the magnetotail of Venus
Barabash, Stas; Zhang, Tielong; Rong, Zhaojin +8 more
Venus serves as the prototype of solar wind interaction with unmagnetized planetary bodies with atmospheres. It has no intrinsic dipole or crustal magnetic field; the only magnetic field is believed to be formed by the draped interplanetary magnetic field (IMF). However, the large-scale magnetic field observed over the north polar region of Venus …