Search Publications
Electron heating and energy inventory during asymmetric reconnection in a laboratory plasma
Roytershteyn, V.; Chen, Li-Jen; Ji, Hantao +6 more
Electron heating and the energy inventory during asymmetric reconnection are studied in the laboratory plasma with a density ratio of about 8 across the current sheet. Features of asymmetric reconnection such as the large density gradients near the low-density side separatrices, asymmetric in-plane electric field, and bipolar out-of-plane magnetic…
Electron temperature anisotropy regulation by whistler instability
Yoon, P. H.; Hwang, J.; Kim, H. P. +1 more
The solar wind electron temperature anisotropy is regulated by a number of physical processes, which include adiabatic expansion, electron Coulomb collisions, and microinstabilities. In the collisionless limit, the measured electron temperature anisotropy is constrained by the marginal threshold conditions for whistler (electromagnetic electron cy…
Phase relationship between ULF waves and drift-bounce resonant ions: A statistical study
Zong, Q. G.; Rankin, R.; Wang, Y. F. +4 more
We explore the phase relationship between the poloidal mode ULF wave electric field oscillations and drift-bounce resonant oxygen ions under the resonant condition of N = 2 at the magnetic equator. Using Cluster data from 2001 to 2004, we identify 55 fundamental poloidal mode wave events, among which 42 show "negative slope" pitch angle dispersion…
Long-Term Variability of Jupiter's Magnetodisk and Implications for the Aurora
Bunce, Emma J.; Clarke, John T.; Vogt, Marissa F. +2 more
Observations of Jupiter's UV auroral emissions collected over several years show that the ionospheric positions of the main emission and the Ganymede footprint can vary by as much as 3° in latitude. One explanation for this shift is a change of Jupiter's current sheet current density, which would alter the amount of field line stretching and displ…
Morphology of Ganymede's FUV auroral ovals
Saur, Joachim; Roth, Lorenz; Feldman, Paul D. +4 more
We study the morphology of Ganymede's FUV aurora by analyzing spectral images obtained over the past two decades by the Space Telescope Imaging Spectrograph on board the Hubble Space Telescope. The observations cover the eastern and western elongation as well as various magnetic latitudes of Ganymede within the Jovian plasma sheet. We find both as…
Spontaneous hot flow anomalies at Mars and Venus
Zhang, Tielong; Futaana, Yoshifumi; Persson, Moa +8 more
We report the first observations of Spontaneous Hot Flow Anomalies (SHFAs) at Venus and Mars, demonstrating their existence in the foreshocks of other planets beyond Earth. Using data from the ESA Venus Express and the NASA Mars Atmosphere and Volatile EvolutioN (MAVEN) spacecraft, we present magnetic and plasma observations from events at both pl…
Cold Ion Outflow Modulated by the Solar Wind Energy Input and Tilt of the Geomagnetic Dipole
Wei, Y.; Nilsson, H.; André, M. +7 more
The solar wind energy input into the Earth's magnetosphere-ionosphere system drives ionospheric outflow, which plays an important role in both the magnetospheric dynamics and evolution of the atmosphere. However, little is known about the cold ion outflow with energies lower than a few tens of eV, as the direct measurement of cold ions is difficul…
IMF dependence of energetic oxygen and hydrogen ion distributions in the near-Earth magnetosphere
Daly, P. W.; Kronberg, E. A.; Nykyri, K. +5 more
Energetic ion distributions in the near-Earth plasma sheet can provide important information for understanding the entry of ions into the magnetosphere and their transportation, acceleration, and losses in the near-Earth region. In this study, 11 years of energetic proton and oxygen observations (> 274 keV) from Cluster/Research with Adaptive P…
The transient topside layer and associated current sheet in the ionosphere of Mars
Gurnett, Donald A.; Halekas, Jasper S.; DiBraccio, Gina A. +2 more
Radar soundings from the Mars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS) instrument on board the Mars Express spacecraft have shown that transient layers exist in the dayside upper ionosphere of Mars. The most prominent of these features is a second layer at an altitude near 200 km, well above that of the main photoionization l…
A hybrid approach to empirical magnetosphere modeling
Tsyganenko, N. A.; Andreeva, V. A.
A new approach has been devised and explored to reconstruct magnetospheric configurations, based on spacecraft data and a synthesis of two methods of modeling the magnetic field of extraterrestrial currents. The main idea is to combine within a single framework (1) a modular structure explicitly representing separate contributions to the total fie…