Search Publications
Merging of coronal and heliospheric numerical two-dimensional MHD models
Luhmann, J. G.; Odstrcil, D.; Riley, P. +4 more
Space weather research requires investigation of a complex chain of coupled dynamic phenomena occurring simultaneously on various spatial and temporal scales between the Sun and Earth. Specialized physically based numerical models have been developed to address particular aspects of the entire system. However, an integrated modeling approach is ne…
Four-point Cluster application of magnetic field analysis tools: The discontinuity analyzer
Balogh, A.; Glassmeier, K. -H.; Dunlop, M. W.
The Cluster spacecraft have collected 3-D information on magnetic field structures at small to medium scales (100-1000 km) in the Earth's dayside magnetosphere, magnetosheath, and near solar wind. We focus here on the first application of the discontinuity analyzer analysis technique (determination of the geometry and motion of magnetic discontinu…
Modeling the heliospheric current sheet: Solar cycle variations
Riley, Pete; Linker, J. A.; Mikić, Z.
In this report we employ an empirically driven, three-dimensional MHD model to explore the evolution of the heliospheric current sheet (HCS) during the course of the solar cycle. We compare our results with a simpler ``constant-speed'' approach for mapping the HCS outward into the solar wind to demonstrate that dynamic effects can substantially de…
On the origin of radial magnetic fields in the heliosphere
Gosling, J. T.; Skoug, R. M.
Numerous examples of events wherein the heliospheric magnetic field (HMF) measured at a fixed point in space remains nearly radial for many hours have been reported in the literature. Such events are observed both in the normal solar wind and within disturbances driven by coronal mass ejections (CMEs). A very large fraction of these extended, near…
April 2000 magnetic storm: Solar wind driver and magnetospheric response
Pulkkinen, Tuija I.; Palmroth, Minna; Pulkkinen, Antti +4 more
On 4 April 2000, a coronal mass ejection (CME) took place close to the western limb of the Sun. The shock front of the CME hit the Earth's magnetosphere on 6 April. A strong interplanetary southward BZ event in the sheath region caused a magnetic storm that was the second strongest in the year 2000 if quantified by the peak of the Dst i…
Four spacecraft measurements of the quasiperpendicular terrestrial bow shock: Orientation and motion
Balogh, A.; Horbury, T. S.; Lucek, E. A. +5 more
Measurements of the magnetic field at the four Cluster spacecraft, typically separated by ~600 km, during bow shock crossings allow the orientation and motion of this structure to be estimated. Results from 48 clean and steady quasiperpendicular crossings during 2000 and 2001, covering local times from 0600 to 1700, reveal the bow shock normal to …
The underlying direction of the heliospheric magnetic field through the Ulysses first orbit
Balogh, A.; Forsyth, R. J.; Smith, E. J.
Between February 1992 and April 1998 the Ulysses spacecraft carried out the first survey of how the properties of the solar wind and heliospheric magnetic field vary with latitude during the declining and minimum phases of the solar cycle. In this paper we report on how the underlying direction of the heliospheric magnetic field varied through the…
Polarity reversal of the solar magnetic field during cycle 23
Andrews, M. D.; Sheeley, N. R.; Wang, Y. -M.
Using magnetograph data, coronagraph observations, and source surface extrapolations, we examine the evolution of the photospheric magnetic field from 1996 through the 2000-2001 polarity reversal and show how this evolution is reflected in coronal holes, coronal streamers, the heliospheric current sheet (HCS), and the solar wind. The photospheric …
Magnetospheric responses to sudden and quasiperiodic solar wind variations
Kim, K. -H.; Andre, M.; Mozer, F. S. +5 more
On April 13 (day 103), 2001, 0700-1400 UT, the Polar satellite experienced different plasma regimes (i.e., magnetosphere, magnetosheath, and solar wind) because of the solar wind dynamic pressure variations and its high orbital inclination near the subsolar magnetopause meridian. When Polar was in the magnetosheath, quasiperiodic spacecraft potent…
Signatures of wave-ion interactions in the solar wind: Ulysses observations
Goldstein, Bruce E.; Neugebauer, Marcia; Gary, S. Peter
Theory and simulations predict that resonant wave-particle scattering by enhanced magnetic fluctuations yields characteristic signatures in properties of solar wind ions. Here Ulysses/Solar Wind Observations Over the Poles of the Sun (SWOOPS) instrument measurements of protons and alpha particles are examined to seek three types of these signature…