Search Publications
A computational and theoretical analysis of falling frequency VLF emissions
Omura, Yoshiharu; Nunn, David
Recently much progress has been made in the simulation and theoretical understanding of rising frequency triggered emissions and rising chorus. Both PIC and Vlasov VHS codes produce risers in the region downstream from the equator toward which the VLF waves are traveling. The VHS code only produces fallers or downward hooks with difficulty due to …
Time-dependent MHD modeling of the global solar corona for year 2007: Driven by daily-updated magnetic field synoptic data
Liu, Yang; Wu, S. T.; Feng, X. S. +3 more
In this paper, we develop a time-dependent MHD model driven by the daily-updated synoptic magnetograms (MHD-DUSM) to study the dynamic evolution of the global corona with the help of the 3D Solar-Interplanetary (SIP) adaptive mesh refinement (AMR) space-time conservation element and solution element (CESE) MHD model (SIP-AMR-CESE MHD Model). To ac…
Saturn's inner magnetospheric convection pattern: Further evidence
Gurnett, D. A.; Thomsen, M. F.; Tokar, R. L. +7 more
Observations of the radial locations of satellite absorption microsignatures in energetic particle data at Saturn have suggested the existence of an average convection pattern, fixed in local time, that is superimposed on the dominant near-corotation of the inner magnetosphere. Such a pattern should have additional observational consequences, and …
Localized density enhancements in the magnetosheath: Three-dimensional morphology and possible importance for impulsive penetration
Nilsson, H.; Karlsson, T.; Trotignon, J. -G. +3 more
We use Cluster multipoint density measurements, using the spacecraft potential, to identify localized density enhancements (>50%) in the magnetosheath, and estimate their three-dimensional morphology and orientation. Typically one dimension of the density enhancements is shorter than others, is directed perpendicular to the background magnetic …
Estimating the capture and loss of cold plasma from ionospheric outflow
Nilsson, H.; André, M.; Eriksson, A. +9 more
An important source of magnetospheric plasma is cold plasma from the terrestrial ionosphere. Low energy ions travel along the magnetic field lines and enter the magnetospheric lobes where they are convected toward the tail plasma sheet. Recent observations indicate that the field aligned ion outflow velocity is sometimes much higher than the conve…
Reconnection at the magnetopause of Saturn: Perspective from FTE occurrence and magnetosphere size
Lai, H. R.; Russell, C. T.; Wei, H. Y. +2 more
Flux transfer events observed at Mercury, Earth, and Jupiter are attributed to spatially and temporally limited events in which the magnetosheath and magnetospheric magnetic field become interconnected and magnetic flux is transported from the dayside to the lobes of the magnetotail. Examination of the Saturnian magnetopause at local times from 10…
Cassini observations of ion and electron beams at Saturn and their relationship to infrared auroral arcs
Coates, A. J.; Brown, R. H.; Baines, K. H. +14 more
We present Cassini Visual and Infrared Mapping Spectrometer observations of infrared auroral emissions from the noon sector of Saturn's ionosphere revealing multiple intense auroral arcs separated by dark regions poleward of the main oval. The arcs are interpreted as the ionospheric signatures of bursts of reconnection occurring at the dayside mag…
Hot and cold ion outflow: Spatial distribution of ion heating
Nilsson, H.; Slapak, R.; André, M. +2 more
Ions apparently emanating from the same source, the ionospheric polar cap, can either end up as energized to keV energies in the high-altitude cusp/mantle, or appear as cold ions in the magnetotail lobes. We use Cluster observations of ions and wave electric fields to study the spatial variation of ion heating in the cusp/mantle and polar cap. The…
Energetic neutral atom observations of magnetic anomalies on the lunar surface
Barabash, S.; Holmström, M.; Futaana, Y. +5 more
SARA, the Sub-KeV Atom Analyzer, on board Chandrayaan-1 recorded the first image of a minimagnetosphere above a lunar magnetic anomaly using energetic neutral atoms (ENAs). It was shown that this magnetosphere, which is located near the Gerasimovich crater, is able to reduce the solar wind ion flux impinging onto the lunar surface by more than 50%…
Oxygen and hydrogen ion abundance in the near-Earth magnetosphere: Statistical results on the response to the geomagnetic and solar wind activity conditions
Dandouras, I.; Daly, P. W.; Kistler, L. M. +4 more
The composition of ions plays a crucial role for the fundamental plasma properties in the terrestrial magnetosphere. We investigate the oxygen-to-hydrogen ratio in the near-Earth magnetosphere from -10 RE < XGSE < 10 RE. The results are based on seven years of ion flux measurements in the energy range ∼10 keV…