Search Publications
Cassini observations of ionospheric photoelectrons at large distances from Titan: Implications for Titan's exospheric environment and magnetic tail
Lewis, G. R.; Coates, A. J.; Jones, G. H. +6 more
Discrete peaks near 24.1 eV are seen in electron spectra measured in Titan's ionosphere by the ELS (Electron Spectrometer), part of the Cassini Plasma Spectrometer (CAPS), and are interpreted as photoelectrons. These photoelectrons are generated as a result of ionization of N2 by the strong solar He II (30.4 nm) line. They are generally…
Pickup protons: Comparisons using the three-dimensional MHD HHMS-PI model and Ulysses SWICS measurements
Sun, Wei; Intriligator, Devrie S.; Detman, Thomas +5 more
We report the first comparisons of pickup proton simulation results with in situ measurements of pickup protons obtained by the SWICS instrument on Ulysses. Simulations were run using the three dimensional (3D) time-dependent Hybrid Heliospheric Modeling System with Pickup Protons (HHMS-PI). HHMS-PI is an MHD solar wind model, expanded to include …
Saturn's auroral/polar H3+ infrared emission: The effect of solar wind compression
Dougherty, Michele K.; Bunce, Emma J.; Melin, Henrik +6 more
Previous investigations into Saturn's aurora have shown that they are strongly controlled by the solar wind. Here, for the first time, we use a combination of ground-based infrared observations of the aurora and in situ measurements of the magnetosphere in order to better understand this association. We show that large-scale variability in both th…
The role of the inner tail to midtail plasma sheet in channeling solar wind power to the ionosphere
Dandouras, I.; André, M.; Hamrin, M. +5 more
In this article we use Cluster power density (E · J) data from 2001, 2002, and 2004 to investigate energy conversion and transfer in the plasma sheet. We show that a southward IMF Bz is favorable for plasma sheet energy conversion, and that there is an increased particle and Poynting flux toward the Earth at times when Cluster observes …
Geometry of the 20 November 2003 magnetic cloud
Park, Sung-Hong; Cho, Kyung-Suk; Kim, Yeon-Han +2 more
This study is an attempt to find a coherent interpretation of the link between the 20 November 2003 magnetic cloud (MC) and its solar source. Most previous studies agree on the orientation of the MC, but the orientation is nearly perpendicular to the axis of the post-eruption arcade (PEA) or the orientation of the neutral line in the solar source …
Statistical model of electron pitch angle diffusion in the outer radiation belt
Krasnoselskikh, V.; Breuillard, H.; Agapitov, O. +2 more
We calculated the bounce averaged electron pitch angle diffusion coefficients ? using the statistical characteristics of lower band chorus activity collected by the Cluster mission from 2001-2009. Nine years of Cluster observations provide the distributions of the θ angle between wave vectors and the background magnetic field; and the distribution…
Observations of oxygen ions in the dayside magnetosheath associated with southward IMF
Nilsson, H.; Slapak, R.; Eriksson, A. +1 more
We present a case study of high energy oxygen ions (O+) observed in the dayside terrestrial magnetosheath, in the southern hemisphere. It is shown that the presence of O+ is strongly correlated to the IMF direction: O+ is observed only for Bz < 0. Three satellites observe O+ immediately at …
A survey of the polar cap density based on Cluster EFW probe measurements: Solar wind and solar irradiation dependence
Haaland, S.; Lybekk, B.; Pedersen, A. +1 more
The plasma density above the Earth's polar caps provide crucial information about the state of the magnetosphere. This region of space is known for its tenuous plasma and extremely low plasma densities, thus making traditional measurements with particle and plasma instruments extremely difficult. A new method based on spacecraft potential measurem…
Multipoint study of magnetosheath magnetic field fluctuations and their relation to the foreshock
Němeček, Z.; Gutynska, O.; Šimůnek, J. +2 more
The magnetosheath is occupied with a variety of low-frequency fluctuations from different sources. Among them, the bow shock and dominantly foreshock processes are often considered as their major contributors. We use distant (Wind) and close (Geotail) interplanetary magnetic field monitors and compare their measurements with simultaneous magnetic …
Determining the full magnetic field gradient from two spacecraft measurements under special constraints
Dunlop, M.; Rong, Z. J.; Shen, C.
In this exploration, it is revealed for the first time that the full magnetic field gradient and current density distribution can be derived from two spacecraft magnetic field measurements under the assumptions that the magnetic field is approximately stationary and force-free, conditions which are particularly relevant to low altitude regions of …