Search Publications
Three-Dimensional Solar Wind Modeling Using Remote-Sensing Data
Jackson, B. V.; Hick, P. P.
We have developed a computer-assisted tomography (CAT) technique that iteratively modifies a kinematic solar wind model to least-squares fit heliospheric remote sensing observations (interplanetary scintillation and Thomson-scattering observations). These remote sensing data cover a large range of solar elongations, and access high-latitude region…
Solar Wind Composition at Solar Maximum
Bochsler, Peter
Although coronal mass ejections have traditionally been thought to contribute only a minor fraction to the total solar particle flux, and although such events mainly occur in lower heliographic latitudes, the impressive spectacle of eruptions - observed with SOHO/LASCO even at times of solar minimum - indicates that an important part of the low-la…
UVCS Observations of Velocity Shear at Streamer Boundaries in the Corona
Habbal, Shadia Rifai; Woo, Richard; Vial, Jean-Claude
Measurements of the intensities of the Ovi 1032 and 1037 Å spectral lines in the southern solar hemisphere, from 1.5 to 5 R_s, were made with the SOHO Ultraviolet Coronagraph Spectrometer (UVCS) in May 2000 close to solar maximum. The ratio of the intensity of the two oxygen lines is used as a proxy for solar wind velocity in the inner corona. Whi…
Rigidity Dependence and Time Response of Cosmic Rays to the Modulation Steps in the Rising Part of Solar Cycle 23. Cospin/ket Results
Kunow, H.; Heber, B.; Müller-Mellin, R. +4 more
Previous work on the latitudinal gradient and on the amplitude of the recurrent cosmic ray decreases, has shown that their magnitude does not decrease monotonically with the particle rigidity, but it presents a broad maximun around 1 2 GV. We have extended this analysis to study the behaviour of cosmic-ray particles during the modulation steps in …
Origins of Anisotropic 40 300 keV Electron Events Observed at Low and High Latitudes
Pick, M.; Gold, R. E.; Hawkins, S. E., III +1 more
Using a survey of anisotropic electron events in the energy range of ∼40 300 keV observed by HI-SCALE on Ulysses, we have selected several time intervals during 1999 when Ulysses traveled from about 20° S at 5.2 AU (January 1999) to 42° S at 4.2 AU (January 2000). We compare these events with observations at ∼1 AU using the nearly identical instru…
Oxygen and Iron Ions at High Heliolatitudes
Lanzerotti, L. J.; Gold, R. E.; Maclennan, C. G.
The fluxes of O and Fe ions at high heliolatitudes measured by the HiScale instrument on Ulysses reflect the dynamical processes that affect the charged particle populations in the heliosphere. Both the O and Fe ions show more latitude dependence in the first (solar minimum) orbit to high southern heliolatitudes than during the second (solar maxim…
Source Region of High and Low Speed Wind during the Spartan 201-05 Flight
Skoug, Ruth; Kucera, Therese; Fisher, Richard +4 more
The large-scale coronal magnetic fields of the Sun are believed to play an important role in organizing the coronal plasma and channeling the high and low speed solar wind along the open magnetic field lines of the polar coronal holes and the rapidly diverging field lines close to the current sheet regions, as has been observed by the instruments …
A Survey of Field-Aligned Mach Number and Plasma Beta in the Solar Wind
De Keyser, Johan; Poedts, Stefaan; Roth, Michel +1 more
We have surveyed solar wind plasma beta and field-aligned Alfvénic Mach number using Ulysses and Wind data. We show the characteristic timescale and occurrence frequency of `magnetically dominated' solar wind, whose interaction with a planetary magnetosphere may produce a bow shock with multiple shock fronts. We discuss radial, latitudinal, and so…
Associating the Solar Wind Measured by Ulysses with its Source at the sun
Habbal, Shadia Rifai; Woo, Richard
Radio occultation, ultraviolet, and white-light measurements have expanded our knowledge of the morphology of density and velocity in polar coronal holes, and made it possible to carry out the first systematic comparisons between the Ulysses solar wind measurements and quantitative white-light observations of the solar corona. This paper summarize…
Comparison of quiet-Sun radiances measured by CDS and SUMER on SOHO
Solanki, S. K.; Wilhelm, K.; Schühle, U. +6 more
Since the beginning of the SOHO (Solar and Heliospheric Observatory) mission an intercalibration programme was carried out which included simultaneous observations of the EUV instruments CDS (Coronal Diagnostic Spectrometer) and SUMER (Solar Ultraviolet Measurements of Emitted Radiation) of common targets on the quiet Sun. The observations in the …