Search Publications
Searching for ULF signatures of the cusp: Observations from search coil magnetometers and auroral imagers in Svalbard
Lorentzen, Dag A.; Kim, Hyomin; Engebretson, Mark J. +4 more
Spacecraft traveling through the cusp at a variety of altitudes have consistently found the cusp to be filled with intense, often irregular power in the upper ULF frequency range. Some ground-based studies have observed narrowband waves in this same frequency range in the vicinity of the cusp foot point, but it has not been possible with magnetome…
Spherical harmonic analysis of particle velocity distribution function: Comparison of moments and anisotropies using Cluster data
Gurgiolo, Chris; Viñas, Adolfo F.
This paper presents a spherical harmonic analysis of the plasma velocity distribution function using high-angular, energy, and time resolution Cluster data obtained from the PEACE spectrometer instrument to demonstrate how this analysis models the particle distribution function and its moments and anisotropies. The results show that spherical harm…
The decay phase of solar energetic particle events
Kecskeméty, K.; Daibog, E. I.; Logachev, Y. I. +1 more
The shape of the particle flux profile in the decay phase of solar energetic particle (SEP) events is of particular importance in understanding the propagation of energetic particles in the interplanetary medium. The majority of few-MeV proton events (>90%) exhibit exponential law declines, suggesting the dominant role of convection transport a…
A possible generation mechanism of interplanetary rotational discontinuities
Lin, C. C.; Lee, L. C.; Tsai, C. L. +3 more
In the present paper, we first examine some interplanetary directional discontinuities with very small B n /B (<0.1) using intraspacecraft timing method. It is found that the velocity and magnetic field fluctuations of these directional discontinuities satisfy the Walén relation. We suggest that these directional discontinuities are…
Oblique lower band chorus waves: Time shifts between discrete elements observed by the Cluster spacecraft
Gurnett, Donald A.; Chum, Jaroslav; Santolik, Ondrej +1 more
We report observations of remarkable frequency differences and time shifts between the corresponding elements of lower band chorus recorded by the four Cluster spacecraft at low magnetic latitudes on 20 January 2004. The Poynting flux measurements made by the Spatio-Temporal Analysis of Field Fluctuations (STAFF) instrument confirm that the chorus…
Relative timing of substorm processes as derived from multifluid/multiscale simulations: Internally driven substorms
Winglee, R. M.; Harnett, E.; Kidder, A.
The role of tail reconnection in initiating substorm onset remains highly controversial. Multifluid/multiscale simulations are used to examine this problem with the unique capability of being able to resolve ion skin depth and ion cyclotron processes within a very thin tail current sheet within a global magnetosphere. It is shown that, consistent …
Solar wind erosion of the polar regions of the Mars ionosphere
Lundin, R.; Pérez-de-Tejada, H.; Reyes-Ruiz, M. +1 more
Measurements conducted with the Analyzer of Space Plasmas and Energetic Atoms (ASPERA-3) instrument of the Mars Express spacecraft provide data of plasma fluxes that stream away from the polar regions of the Mars ionosphere with energy spectra whose peak value increases with distance from the planetary surface. The observed energy distribution rev…
Can magnetotail reconnection produce the auroral intensities observed in the conjugate ionosphere?
Snekvik, K.; Østgaard, N.; Haaland, S. E. +5 more
In a recent case study, Borg et al. (2007) reported that an inverted V structure, caused by a field-aligned potential drop of 30 kV producing very strong X-ray aurora, was found in connection with tail reconnection. However, the in situ particle measurements indicated clearly that the particles responsible for the X-ray aurora were not accelerated…
Deformation and evolution of solar wind discontinuities through their interactions with the Earth's bow shock
Dandouras, I.; Nakamura, R.; Lucek, E. A. +13 more
The present study examines the interaction of solar wind discontinuities with the Earth's bow shock, using multipoint observations in the magnetosheath by Time History of Events and Macroscale Interactions During Substorms (THEMIS), Cluster, and Double Star TC1. We focus on the deformation and evolution of two discontinuities observed on 21 June 2…
Plasmoid-like structures in multiple X line Hall MHD reconnection
Lu, Q. M.; Liu, C. X.; Jin, S. P. +2 more
Driven by a waveform inflow, multiple X line reconnection is initiated in a long current layer, and the plasmoids are bound between two neighboring reconnection sites. We investigate the behaviors of the plasmoid-like structures in the absence and presence of an initial guide field B y0 normalized by B 0 (B 0 is t…