Search Publications
Solar cycle variations in ion composition in the dayside ionosphere of Titan
Wahlund, J. -E.; Edberg, N. J. T.; Waite, J. H. +4 more
One Titanian year spans over two complete solar cycles, and the solar irradiance has a significant effect on ionospheric densities. Solar cycle 24 has been one of the quietest cycles on record. In this paper we show data from the Cassini ion and neutral mass spectrometer (INMS) and the radio and plasma wave science Langmuir probe spanning the time…
Cluster observations of non-time continuous magnetosonic waves
Boardsen, Scott A.; Sibeck, David G.; Walker, Simon N. +3 more
Equatorial magnetosonic waves are normally observed as temporally continuous sets of emissions lasting from minutes to hours. Recent observations, however, have shown that this is not always the case. Using Cluster data, this study identifies two distinct forms of these non-temporally continuous emissions. The first, referred to as rising tone emi…
Partitioning of integrated energy fluxes in four tail reconnection events observed by Cluster
Goldstein, Melvyn; Gurgiolo, Chris; Thaller, Scott +4 more
We present the partitioning of integrated energy flux from four tail reconnection events observed by Cluster, focusing on the relative contributions of Poynting flux, electron, H+ and O+ enthalpy, and kinetic energy flux in the tailward and earthward directions in order to study temporal and spatial features of each event. We further subdivide the…
On improving the accuracy of electron density profiles obtained at high altitudes by the ionospheric sounder on the Mars Express spacecraft
Gurnett, D. A.; Němec, F.; Morgan, D. D.
We attempt to improve the standard inversion routine used to obtain electron density profiles from the data measured by the Mars Advanced Radar for Subsurface and Ionospheric Sounding (MARSIS) topside radar sounder on board the Mars Express spacecraft. Artificial ionospheric traces corresponding to how the MARSIS instrument would see model electro…
Hemispheric asymmetry in the near-Venusian magnetotail during solar maximum
Zhang, T. L.; Baumjohann, W.; Xiao, S. D.
During solar minimum the near-Venusian magnetotail exhibits a hemispheric asymmetry in the cross-tail field distribution. It implies that the magnetic field lines in the -E hemisphere are wrapped more tightly around Venus than in the +E hemisphere. Therefore, a strong field reversal region occurs in the magnetotail, which is prone to the magnetic …
Coronal magnetic field profiles from shock-CME standoff distances
Gopalswamy, N.; Cairns, Iver H.; Yashiro, S. +1 more
Coronagraphs observe coronal mass ejections (CMEs) and driven shocks in white light images. From these observations the shock's speed and the shock's standoff distance from the CME's leading edge can be derived. Using these quantities, theoretical relationships between the shock's Alfvénic Mach number MA and standoff distance, and empirical radial…
A 17 June 2011 polar jet and its presence in the background solar wind
Jackson, B. V.; Buffington, A.; Hick, P. P. +3 more
High-speed jet responses in the polar solar wind are enigmatic. Here we measure a jet response that emanates from the southern polar coronal hole on 17 June 2011 at the extreme speed of over 1200 km/s. This response was recorded from the Sun-Earth line in Solar Dynamics Observatory/Atmospheric Imaging Assembly (SDO/AIA) and Large Angle and Spectro…
Milne-Eddington inversion for unresolved magnetic structures in the quiet Sun photosphere
Bommier, Véronique
This paper is first devoted to present our method for modeling unresolved magnetic structures in the Milne-Eddington inversion of spectropolarimetric data. The related definitions and other approaches and different used inversion algorithms are recalled for comparison. In a second part, we apply our method to quiet Sun data outside active regions.…
Some new aspects of the transient ionization layer of comet Siding Spring origin in the Martian upper atmosphere
Venkateswara Rao, N.; Rao, S. V. B.; ManasaMohana, P. +1 more
The close encounter of comet Siding Spring with Mars resulted in the formation of a dense transient ionization layer in the Martian upper atmosphere at altitudes between 80 and 120 km. Instruments on three spacecraft orbiting Mars detected the presence of this layer, as reported in previous publications. In this study, we reanalyzed the ionograms …
MHD-IPS analysis of relationship among solar wind density, temperature, and flow speed
Hayashi, Keiji; Tokumaru, Munetoshi; Fujiki, Ken'ichi
The solar wind properties near the Sun are a decisive factor of properties in the rest of heliosphere. As such, determining realistic plasma density and temperature near the Sun is very important in models for solar wind, specifically magnetohydrodynamics (MHD) models. We had developed a tomographic analysis to reconstruct three-dimensional solar …