Search Publications
Heliospheric magnetic field polarity inversions at high heliographic latitudes
Balogh, A.; Horbury, T. S.; Lucek, E. A. +2 more
The heliospheric magnetic field over the poles of the sun has been examined to identify intervals when the polarity of the magnetic field deviates significantly from the calculated Parker spiral, using Ulysses observations in 1994 and 1995, near solar minimum. Intervals with deviation > 90° have been identified, corresponding to magnetic field …
Long-term drift of the coronal source magnetic flux and the total solar irradiance
Lockwood, M.; Stamper, R.
We test the method of Lockwood et al [1999] for deriving the coronal source flux from the geomagnetic aa index and show it to be accurate to within 12% for annual means and 4.5% for averages over a sunspot cycle. Using data from four solar constant monitors during 1981-1995, we find a linear relationship between this magnetic flux and the total so…
Evidence of a solar origin for pressure balance structures in the high-latitude solar wind
Reisenfeld, D. B.; McComas, D. J.; Steinberg, J. T.
Ulysses observations of the high-latitude solar wind have shown that on time scales of < 1 day, the polar wind is dominated by pressure balance structures (PBSs). Fluctuations of the plasma beta within PBSs appear to be strongly correlated with fluctuations in the helium abundance. The correlation occurs in both the northern and southern hemisp…
Differences in the temporal variations of galactic cosmic ray electrons and protons: Implications from Ulysses at solar minimum
Sierks, H.; Kunow, H.; Bothmer, V. +8 more
According to standard drift dominated modulation models the intensity variations of galactic cosmic ray protons and electrons respond differently to the latitudinal extension of the heliospheric current sheet α. In an A>0 solar cycle intensities of protons should vary weakly with the latitudinal extension, whereas electrons should show a strong…
The global nature of solar cycle variations of the solar wind dynamic pressure
Wang, Chi; Richardson, John
The solar wind dynamic pressure measured near the ecliptic varies over the solar cycle. A major unanswered question has been whether this variation is a global feature or restricted to low latitudes and thus perhaps a consequence of the changing heliospheric current sheet configuration. We use plasma data from IMP-8, Ulysses and Voyager 2 to show …
Ulysses measurements of variations in the solar wind-interstellar hydrogen charge exchange rate
McComas, D. J.; Gosling, J. T.; Pryor, W. R. +1 more
Charge exchange with solar wind protons is the primary ionization process for interstellar hydrogen traveling through the heliosphere. In this study we use Ulysses solar wind observations to examine and quantify variations in charge exchange. We find that these variations are largest within stream interaction regions where the charge exchange rate…
Observations of heliospheric planar and offset-planar magnetic structures
Balogh, A.; Jones, G. H.; Horbury, T. S.
Planar magnetic structures are regions of solar wind plasma where the magnetic field orientation is constrained within a fixed plane for durations of several hours. Within these structures, magnetic field discontinuities are seen, with the discontinuity surfaces being almost co-planar. The results of a survey of planar magnetic strutures detected …
The electron heat flux in the polar solar wind: Ulysses observations
Scime, Earl E.; Littleton, J. E.; Badeau, Allen E., Jr.
Ulysses measurements of the solar wind electron heat flux as a function of heliographic latitude are presented. Contamination from a light leak at the highest latitudes has been removed from the data by interpolating between uncontaminated pixels. After normalization by the radial gradient in the electron heat flux obtained during the inecliptic p…
Energetic particle abundances at CIR shocks
Fränz, M.; Keppler, E.; Mason, G. M. +3 more
The forward and reverse shocks that bound corotating interaction regions (CIRs) travel into different solar wind regimes. In order to test whether the energetic ions associated with the CIR shocks reflect the ambient solar wind, we investigate the elemental composition of 0.1-4.0 MeV/N ions in CIRs observed from 1 to 5 AU with instrumentation on b…
Current sheet control of recurrent particle increases at 4-5 AU
Lario, D.; Balogh, A.; Maksimovic, M. +5 more
We examine the relation between the current sheet as derived from observations of the Sun's neutral line, and recurrent particle increases associated with co-rotating interactions regions (CIR) at 4 to 5 AU radial distance as observed by the Ulysses spacecraft during its first out-of-ecliptic orbit around the Sun. We compare observations during th…