Search Publications
A new form of Saturn's magnetopause using a dynamic pressure balance model, based on in situ, multi-instrument Cassini measurements
Coates, A. J.; Krupp, N.; Dougherty, M. K. +9 more
The shape and location of a planetary magnetopause can be determined by balancing the solar wind dynamic pressure with the magnetic and thermal pressures found inside the boundary. Previous studies have found the kronian magnetosphere to show rigidity (like that of Earth) as well as compressibility (like that of Jupiter) in terms of its dynamics. …
Reconstruction of solar spectral irradiance since the Maunder minimum
Solanki, S. K.; Krivova, N. A.; Vieira, L. E. A.
Solar irradiance is the main external driver of the Earth's climate. Whereas the total solar irradiance is the main source of energy input into the climate system, solar UV irradiance exerts control over chemical and physical processes in the Earth's upper atmosphere. The time series of accurate irradiance measurements are, however, relatively sho…
Conjugate ground and multisatellite observations of compression-related EMIC Pc1 waves and associated proton precipitation
Glassmeier, K. -H.; Matsui, H.; Fornacon, K. -H. +10 more
We present coordinated ground satellite observations of solar wind compression-related dayside electromagnetic ion cyclotron (EMIC) waves from 25 September 2005. On the ground, dayside structured EMIC wave activity was observed by the CARISMA and STEP magnetometer arrays for several hours during the period of maximum compression. The EMIC waves we…
Theory and observation of electromagnetic ion cyclotron triggered emissions in the magnetosphere
Dandouras, Iannis; Masson, Arnaud; Omura, Yoshiharu +5 more
We develop a nonlinear wave growth theory of electromagnetic ion cyclotron (EMIC) triggered emissions observed in the inner magnetosphere. We first derive the basic wave equations from Maxwell's equations and the momentum equations for the electrons and ions. We then obtain equations that describe the nonlinear dynamics of resonant protons interac…
Enceladus plume variability and the neutral gas densities in Saturn's magnetosphere
Johnson, R. E.; Mitchell, D. G.; Smith, H. T. +3 more
Neutral particle dominance over charged particles in Saturn's magnetosphere was evident prior to Cassini's arrival at Saturn in 2004. The observation of active plumes emanating from the south pole of Enceladus suggests that this small moon is likely to be the principal source of neutrals in Saturn's magnetosphere. Cassini has flown through the plu…
Features of separatrix regions in magnetic reconnection: Comparison of 2-D particle-in-cell simulations and Cluster observations
Wang, Shui; Huang, Can; Vaivads, Andris +4 more
In collisionless magnetic reconnection, the in-plane Hall currents are carried mainly by the magnetized electrons. The in-plane Hall currents are directed toward the X line along the magnetic field lines just inside the separatrices and away from the X line along the separatrices. Such a current system leads to the quadrupole out-of-plane magnetic…
Cassini observations of a Kelvin-Helmholtz vortex in Saturn's outer magnetosphere
Coates, A. J.; Krupp, N.; Dougherty, M. K. +9 more
We present Cassini observations of a plasma vortex in Saturn's dayside outer magnetosphere. The vortex encounter took place on 13 December 2004 as Cassini was travelling toward the planet. The spacecraft crossed the magnetopause 3 times, before being immersed in the low-latitude boundary layer. During the transition between the boundary layer and …
Heliospheric evolution of solar wind small-scale magnetic flux ropes
Moldwin, M. B.; Cartwright, M. L.
We present results from the first comprehensive small-scale flux rope survey between 0.3 and 5.5 AU using the Helios 1, Helios 2, IMP 8, Wind, ACE, and Ulysses spacecrafts to examine their occurrence rate, properties, and evolution. Small-scale flux ropes are similar to magnetic clouds and can be modeled as a constant-alpha, force-free, cylindrica…
Magnetospheric period oscillations at Saturn: Comparison of equatorial and high-latitude magnetic field periods with north and south Saturn kilometric radiation periods
Coates, A. J.; Dougherty, M. K.; Lamy, L. +4 more
It has recently been shown using Cassini radio data that Saturn kilometric radiation (SKR) emissions from the Northern and Southern hemispheres of Saturn are modulated at distinctly different periods, ∼10.6 h in the north and ∼10.8 h in the south, during the southern summer conditions that prevailed during the interval from 2004 to near-equinox in…
Influence of spacecraft outgassing on the exploration of tenuous atmospheres with in situ mass spectrometry
Wurz, P.; Altwegg, K.; Balsiger, H. +10 more
In situ mass spectrometry has been a powerful tool in many space missions to investigate atmospheres and exospheres of different bodies in the solar system. Applying new technologies, the mass spectrometers have become increasingly more sensitive. In this study, we show that spacecraft outgassing, which can never be completely prevented, will be t…