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…
Coronagraph observations of inflows during high solar activity
Simnett, G. M.; Howard, R. A.; Sheeley, N. R., Jr. +2 more
Since the start of the SOHO mission three years ago, the Large Angle Spectrometric Coronagraph (LASCO) has recorded numerous examples of small, faint features moving inward through the corona. The inflows are observed at heliocentric distances of 2-4 Rs and became increasingly common during 1998, as solar and coronal mass ejection (CME)…
Astrometric and space-geodetic observations of polar wander
Vondrák, Jan; Gross, Richard S.
Optical astrometric measurements of star positions taken during the past century have been recently re-reduced using the final Hipparcos star catalog in order to determine variations in the mean location of the Earth's rotation pole with respect to the Earth's crust. This newly available polar motion series, which is the longest homogeneous polar …
Streamer disconnection events observed with the LASCO coronagraph
Lamy, P. L.; Howard, R. A.; Sheeley, N. R., Jr. +2 more
We present Large Angle Spectrometric Coronagraph (LASCO) observations of two events that suggest magnetic disconnection in coronal streamers. During the 1-2 days preceding each event, successions of narrow looptops are seen rising slowly through the 2-6 RS field of view, forming a bright streamer stalk which continues to elongate with t…
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 …
Direct evidence of the interstellar gas flow velocity in the pickup ion cut-off as observed with SOHO CELIAS CTOF
Bochsler, P.; Klecker, B.; Möbius, E. +9 more
He+ pickup ions as observed with SOHO CELIAS CTOF have been analyzed for the time period DOY 160-190, 1996. During this time of the year the Earth is on the upwind side of the interstellar gas flow with respect to the sun. The high-speed cut-off in the frame of the sun is significantly higher v/Vsw = 2, predicted for pickup i…
Ion-cyclotron wave dissipation channel for Alfvén waves
Kaghashvili, Edisher Kh.
The effect of inhomogeneous velocity flow on Alfvén wave dynamics in the solar wind is investigated. Unlike existing studies in this field that model energy deposition from high-frequency waves to solar wind particles, we consider here the possibility of obtaining high-frequency waves (in this case fast magnetosonic waves) from the ordinary Alfvén…