Search Publications
Relationship between CME Speed and Geomagnetic Storm Intensity
Venkatakrishnan, P.; Srivastava, Nandita
In this paper, we discuss the solar origin and interplanetary consequences of the coronal mass ejection of March 29, 2001 that was responsible for the most intense geomagnetic storm (DST ~ -377 nT) of the current solar cycle to date. A comparison of the CME of March 29, 2001, with a set of geo-effective halo CMEs associated with X-class…
Relationship between discontinuities, magnetic holes, magnetic decreases, and nonlinear Alfvén waves: Ulysses observations over the solar poles
Balogh, A.; Lakhina, G. S.; Tsurutani, B. T. +6 more
Ulysses magnetic field data are used to study magnetic field microstructure over the solar poles. Magnetic holes (MHs) and magnetic decreases (MDs) are found to be located at the phase-steepened edges of nonlinear Alfvén waves. The phase-steepened edges (directional discontinuities) occur in time-coincidence with MHs, one edge of an MD, or through…
Solar wind from high-latitude coronal holes at solar maximum
McComas, D. J.; Elliott, H. A.; von Steiger, R.
In this study we combine Ulysses' observations from the solar wind plasma (SWOOPS) and ion composition (SWICS) instruments to study high-latitude coronal holes near solar maximum for the first time. While chromospheric and coronal composition signatures indicate that there is a unique type of solar wind, which flows from coronal holes, variations …
The draping of heliospheric magnetic fields upstream of coronal mass ejecta
Balogh, A.; Jones, G. H.; Forsyth, R. J. +1 more
The propagation of a fast coronal mass ejection through the interplanetary medium results in compression and draping of existing heliospheric magnetic fields, forming an upstream sheath. Such sheaths are a common context for planar magnetic structures, where the magnetic field is ordered into laminar sheets. A technique is presented to estimate th…
Strongly underwound magnetic fields in co-rotating rarefaction regions: Observations and Implications
Smith, E. J.; Schwadron, N. A.; Murphy, N.
Observations of the magnetic field orientation in co-rotating rarefaction regions (CRRs) reveals that the field can be significantly more radial than predicted by the Parker model. In particular, CRRs sampled by the Ulysses spacecraft beyond 4 AU from the sun often show average field orientations deviating by more than 30° from the expected Archim…
Interplanetary radio emission due to interaction between two coronal mass ejections
Gopalswamy, Nat; Howard, Russell A.; Yashiro, Seiji +2 more
We report on the detection of a new class of nonthermal radio emission due to the interaction between two coronal mass ejections (CMEs). The radio emission was detected by the Radio and Plasma Wave Experiment (WAVES) on board the Wind satellite, while the CMEs were observed by the white-light coronagraphs of the Solar and Heliospheric Observatory …
Cluster observations of fast magnetosonic waves in the terrestrial foreshock
Balogh, A.; Dandouras, I.; Eastwood, J. P. +2 more
Cluster observations of ULF waves in the terrestrial foreshock are presented. Four spacecraft timing techniques on magnetic field measurements are used with plasma bulk velocity measurements to determine wave properties in the plasma rest frame. Based on the propagation speed and polarisation, the waves are found to be fast magnetosonic. The analy…
Ionospheric and dayglow responses to the radiative phase of the Bastille Day flare
Mariska, J. T.; Warren, H. P.; Judge, D. L. +11 more
The Sun's Bastille Day flare on July 14, 2000 produced a variety of geoeffective events. This solar eruption consisted of an X-class flare followed by a coronal mass ejection that produced a major geomagnetic storm. We have undertaken a study of this event beginning with an analysis of the effects of the radiative phase of the flare on the dayglow…
A telescopic and microscopic view of a magnetospheric substorm on 31 March 2001
Mitchell, D. G.; Daly, P. W.; Baker, D. N. +6 more
On March 31, 2001 at ~0635 UT when the CLUSTER constellation was near local midnight and at ~4 RE geocentric distance, sensors observed an energetic electron injection event associated with a strong (AE ~ 1200 nT) magnetospheric substorm. Geostationary spacecraft 1991-080 located at ~20 LT also saw an abrupt electron injection event at …
Relation between Pressure Balance Structures and polar plumes from Ulysses high latitude observations
Sakurai, Takashi; Suess, Steven T.; Yamauchi, Yohei
Ulysses observations have shown that pressure balance structures (PBSs) are a common feature in high-latitude, fast solar wind near solar minimum. Previous studies of Ulysses/SWOOPS plasma data suggest these PBSs may be remnants of coronal polar plumes. Here we find support for this suggestion in an analysis of PBS magnetic structure. We used Ulys…