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Cluster observations of the heliospheric current sheet and an associated magnetic flux rope and comparisons with ACE
Balogh, A.; Eastwood, J. P.; Dunlop, M. W. +1 more
Cluster and ACE magnetic field measurements from the 13 February 2001 are presented. On this day the four Cluster spacecraft made two crossings of the heliospheric current sheet (HCS) while in the solar wind and observed a large-scale rotation of the magnetic field in the magnetosheath. These features were also observed by ACE upstream of the Eart…
Ulysses Cosmic Ray and Solar Particle Investigation/Kiel Electron Telescope observations: Charge sign dependence and spatial gradients during the 1990-2000 A > 0 solar magnetic cycle
Kunow, H.; Wibberenz, G.; Ferreira, S. E. S. +10 more
Ulysses, launched in October 1990, began its second out-of-ecliptic orbit in September 1997. From 1991 to mid-2000, solar polar magnetic field observations indicate a magnetic field pointing outward over the northern polar region (A > 0 epoch). While the first fast latitude scan in 1994/1995 was performed around solar minimum, the second Ulysse…
Solar mean magnetic field variability: A wavelet approach to Wilcox Solar Observatory and SOHO/Michelson Doppler Imager observations
Liu, Wei; Hoeksema, J. Todd; Scherrer, Philip H. +2 more
Solar mean magnetic field (SMMF) measurements from the Wilcox Solar Observatory and with the SOHO/MDI instrument are described and analyzed. Even though two completely different methods of observation are used, the two data sets obtained show a strong similarity. Using continuous wavelet transforms, SMMF variability is found at a number of tempora…
Wind and ACE observations during the great flow of 1-4 May 1998: Relation to solar activity and implications for the magnetosphere
Farrugia, C. J.; Mason, G. M.; Matsui, H. +13 more
Using magnetic field, plasma, and energetic particle data from Wind and ACE, we analyze interplanetary features associated with the first strongly geoeffective interval in the rising phase of solar cycle 23, which affected Earth on 1-4 May 1998. As shown by [1999], the configuration consisted of a compound stream made up of an interplanetary coron…
Evolution of a semicircular flux rope with two ends anchored in the photosphere
van Ballegooijen, A. A.; Lin, J.; Forbes, T. G.
We investigated a coronal magnetic configuration including a semicircular flux rope with two ends anchored in the photosphere. The background field is produced by two source regions on the photosphere. We study the evolution of this configuration in response to the gradual change in the background field, which is modeled by varying either the stre…
Observation of the terrestrial bow shock in quasi-electrostatic subshock regime
Balogh, A.; Eriksson, A.; Walker, S. N. +8 more
Electric field measurements made on board the four Cluster II satellites are used to estimate the spatial scale of the electrostatic potential in the front of the terrestrial bow shock in the quasi-perpendicular regime. High-amplitude electric fields (up to 70 mV m-1) were measured at the shock fronts encountered on 31 March 2001. The m…
Response of interplanetary glow to global variations of hydrogen ionization rate and solar Lyman α flux
Bzowski, Maciej; Summanen, Tuula; Ruciński, Daniel +1 more
The aim of the paper is to investigate the influence of the solar cycle variations of the radiation pressure and time- and heliolatitude-dependent ionization rate on the spatial distribution and temporal evolution of the interplanetary hydrogen Lyman α glow, observed from 1 AU. We identify the variables affecting the distribution and evolution of …
Low-latitude solar wind during the Fall 1998 SOHO-Ulysses quadrature
Biesecker, D. A.; Poletto, G.; Ko, Y. -K. +4 more
The Fall 1998 Solar and Heliospheric Observatory (SOHO)-Ulysses quadrature occurred when Ulysses was at 5.2 AU, 17.4°S of the equator, and off the west limb of the Sun. SOHO coronal observations, at heliocentric distances of a few solar radii, showed that the line through the solar center and Ulysses crossed, over the first days of observations, a…
Correlation of magnetic field intensities and solar wind speeds of events observed by ACE
Owens, Mathew J.; Cargill, Peter J.
The relationship between the magnetic field intensity and speed of solar wind events is examined using ~3 years of data from the ACE spacecraft. No preselection of coronal mass ejections (CMEs) or magnetic clouds is carried out. The correlation between the field intensity and maximum speed is shown to increase significantly when |B| > 18 nT for…
Origin of the May 1998 suprathermal particles: Solar and Heliospheric Observatory/Charge, Element, and Isotope Analysis System/(Highly) Suprathermal Time of Flight results
Wurz, P.; Klecker, B.; Wimmer-Schweingruber, R. F. +4 more
The Solar and Heliospheric Observatory/Charge, Element, and Isotope Analysis System/(Highly) Suprathermal Time of Flight ((H)STOF) mass spectrometer measures the elemental composition and the charge state distribution of ions with suprathermal energies in the range 10-4000 keV amu-1 from above the solar wind particle distribution up to …