Search Publications
Empirical Modeling of the Geomagnetosphere for SIR and CME-Driven Magnetic Storms
Tsyganenko, N. A.; Andreeva, V. A.
During geomagnetic disturbances, the solar wind arrives in the form of characteristic sequences lasting from tens of hours to days. The most important magnetic storm drivers are the coronal mass ejections (CMEs) and the slow-fast stream interaction regions (SIRs). Previous data-based magnetic field models did not distinguish between these types of…
Multiband Study of a Bidirectional Jet Occurred in the Upper Chromosphere
Reeves, Katharine K.; Ni, Lei; Lin, Jun +3 more
We present a study of a jet observed by the Solar Dynamics Observatory (SDO) and the Interface Region Imaging Spectrograph (IRIS), which provide high spatial-temporal resolution observational data of (extreme) ultraviolet images, spectra, and magnetograms. The jet was observed in multiple bands of AIA and manifested clear bidirectional flows in IR…
Extremely High Plasma Densities in the Mars Ionosphere Associated With Cusp-Like Magnetic Fields
Fallows, K.; Withers, P.; Kopf, A. +1 more
The Martian crustal magnetic field modifies the structure of the ionosphere, the loss of atmosphere to space, and the interactions of the upper atmosphere with the solar wind. The Mars Advanced Radar for Subsurface and Ionosphere Sounding topside sounder on Mars Express has regularly observed oblique echoes from magnetically controlled plasma stru…
Jupiter's Dark Polar Region as Observed by the Hubble Space Telescope During the Juno Approach Phase
Nichols, J. D.; Bunce, E. J.; Swithenbank-Harris, B. G.
We present an analysis of Jupiter's dark polar region, previously described as a crescent-shaped region devoid of emission along the dawnside poleward of the main oval. Using ultraviolet images obtained by the Hubble Space Telescope between days of year 137 and 176, coupled with interplanetary data captured during the approach phase of the NASA Ju…
Magnetic Field Observations on Cassini's Proximal Periapsis Passes: Planetary Period Oscillations and Mean Residual Fields
Dougherty, M. K.; Cowley, S. W. H.; Bunce, E. J. +4 more
We analyze periapsis pass magnetic field data from the final 23 orbits of the Cassini spacecraft at Saturn, uniquely encompassing auroral, subauroral, ring region, and intra-ring field lines, to determine the planetary period oscillations (PPOs) and mean residual fields in these regions. Dual modulation by northern and southern PPO systems is foun…
Reconstruction of Local Magnetic Structures by a Modified Radial Basis Function Method
Semenov, V. S.; Tsyganenko, N. A.; Andreeva, V. A. +2 more
Local magnetic structures in space environments, in particular, those in the diffusion region such as magnetic nulls or separators, are very difficult to identify by satellite measurements but important for understanding of magnetic reconnection. Multi-spacecraft missions such as Cluster or MMS, however, provide an opportunity to reconstruct the f…
Efficacy of Electric Field Models in Reproducing Observed Ring Current Ion Spectra During Two Geomagnetic Storms
Kistler, L. M.; Mouikis, C. G.; Matsui, H. +4 more
We use the UNH-IMEF, Weimer 1996, https://doi.org/10.1029/96GL02255 and Volland-Stern electric field models along with a dipole magnetic field to calculate drift paths for particles that reach the Van Allen Probes' orbit for two inbound passes during two large geomagnetic storms. We compare the parti…
Energy Spectral Properties of Hydrogen Energetic Neutral Atoms Emitted From the Dayside Atmosphere of Mars
Barabash, S.; Futaana, Y.; Wurz, P. +3 more
The energy spectrum of hydrogen energetic neutral atoms (HENAs) emitted from the dayside atmosphere of Mars reveals the physical processes of their origin and provides means for remote sensing on the Mars plasma environment. We first compile all available energy spectra of sunward flowing HENA using high-energy resolution data from the neutral par…
Signatures of Magnetic Separatrices at the Borders of a Crater Flux Transfer Event Connected to an Active X-Line
Eastwood, J. P.; Lavraud, B.; Dunlop, M. W. +7 more
In this paper, we present Magnetospheric Multiscale (MMS) observations of a flux transfer event (FTE) characterized by a clear signature in the magnetic field magnitude, which shows maximum at the center flanked by two depressions, detected during a period of stable southward interplanetary magnetic field. This class of FTEs are called "crater-FTE…
Abnormal Subauroral Ion Drifts (ASAID) and Pi2s During Cross-Tail Current Disruptions Observed by Polar on the Magnetically Quiet Days of October 2003
Horvath, Ildiko; Lovell, Brian C.
In this study we further investigate the development of abnormal subauroral ion drifts/polarization streams (ASAID/ASAPS) during the magnetically quiet days of 9-10 October 2003. Our main aim is to provide direct observational evidence verifying that the Defense Meteorological Satellite Program F15 detected quiet-time ASAID/ASAPS features develope…