Search Publications
Mapping the electron energy in Jupiter's aurora: Hubble spectral observations
Bonfond, B.; Clarke, J. T.; Waite, J. H. +6 more
Far ultraviolet spectral observations have been made with the Hubble Space Telescope in the time-tag mode using the Space Telescope Imaging Spectrograph (STIS) long slit. The telescope was slewed in such a way that the slit projection scanned from above the polar limb down to midlatitudes, allowing us to build up the first spectral maps of the FUV…
A "breathing" source surface for cycles 23 and 24
Sun, X.; Arden, W. M.; Norton, A. A.
The potential field source surface (PFSS) model is used to represent the large-scale geometry of the solar coronal magnetic fields. The height of the source surface in this model can be taken as a free parameter. Previous work suggests that varying the source surface height during periods of solar minimum yields better agreement between PFSS model…
Full-halo coronal mass ejections: Arrival at the Earth
Wang, Yuming; Shen, Chenglong; Wang, S. +3 more
A geomagnetic storm is mainly caused by a frontside coronal mass ejection (CME) hitting the Earth and then interacting with the magnetosphere. However, not all frontside CMEs can hit the Earth. Thus, which CMEs hit the Earth and when they do so are important issues in the study and forecasting of space weather. In our previous work, the deprojecte…
The origin of Saturn's magnetic periodicities: Northern and southern current systems
Cowley, S. W. H.; Southwood, D. J.
The recent survey by Andrews et al. (2012) of the separate northern and southern ~10.7 h periodic magnetic signals in Saturn's magnetosphere limits very much their governing current systems. The existence of signals with pure or close to pure northern or southern periods in respective polar caps taken with the relatively narrow bandwidth of the si…
Oblique reflections in the Mars Express MARSIS data set: Stable density structures in the Martian ionosphere
Gurnett, D. A.; André, M.; Edberg, N. J. T. +6 more
The Mars Advanced Radar for Subsurface and Ionospheric Sounding (MARSIS) onboard the European Space Agency's Mars Express (MEX) spacecraft routinely detects evidence of localized plasma density structures in the Martian dayside ionosphere. Such structures, likely taking the form of spatially extended elevations in the plasma density at a given alt…
Interaction of magnetic reconnection and Kelvin-Helmholtz modes for large magnetic shear: 2. Reconnection trigger
Ma, Xuanye; Otto, Antonius; Delamere, Peter A.
A typical property of magnetopause reconnection is a significant perpendicular shear flow due to the fast streaming magnetosheath plasma. Therefore, the magnetopause represents a large magnetic and flow shear boundary during periods of southward interplanetary magnetic field, which can be unstable to Kelvin-Helmholtz (KH) modes and to magnetic rec…
Properties of Kelvin-Helmholtz waves at the magnetopause under northward interplanetary magnetic field: Statistical study
Wang, Chi; Li, Wenya; Tang, Binbin +3 more
We search the plasma and magnetic field data of the Time History of Events and Macroscale Interactions during Substorms (THEMIS) probes B and C during 2008 and 2009 for observation evidences of the Kelvin-Helmholtz instability (KHI). Fourteen KHI events with rolled-up vortices are identified under the northward interplanetary magnetic field (IMF) …
The solar meridional circulation and sunspot cycle variability
Hathaway, D. H.; Upton, L.
We have measured the meridional motions of the magnetic elements in the Sun's surface layers since 1996 and find systematic and substantial variations. In general the meridional flow speed is fast at cycle minima and slow at cycle maxima. We find that these systematic variations are characterized by a weakening of the meridional flow on the polewa…
Effects of a strong ICME on the Martian ionosphere as detected by Mars Express and Mars Odyssey
Gurnett, D. A.; Mitrofanov, I.; Fränz, M. +8 more
We present evidence of a substantial ionospheric response to a strong interplanetary coronal mass ejection (ICME) detected by the Mars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS) on board the Mars Express (MEX) spacecraft. A powerful ICME impacted the Martian ionosphere beginning on 5 June 2011, peaking on 6 June, and trailing o…
Properties of dust particles near Saturn inferred from voltage pulses induced by dust impacts on Cassini spacecraft
Gurnett, D. A.; Kempf, S.; Kurth, W. S. +5 more
The Cassini Radio and Plasma Wave Science (RPWS) instrument can detect dust particles when voltage pulses induced by the dust impacts are observed in the wideband receiver. The size of the voltage pulse is proportional to the mass of the impacting dust particle. For the first time, the dust impacts signals measured by dipole and monopole electric …