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The Influence of Tilt Angle and Magnetic Field Variations on Cosmic ray Modulation
Wibberenz, G.; Cane, H. V.; Richardson, I. G. +1 more
The maximum inclination of the heliospheric current sheet (the tilt angle) and the magnitude B of the heliospheric magnetic field are often used to characterize cosmic ray (CR) modulation. The relevance of B is likely to be the coupling of the interplanetary diffusion coefficients K to the field magnitude in a relation K∝ B -n. In this …
Energetic Particle Characteristics in the High-Latitude Heliosphere Near Solar Maximum
Simnett, G. M.
This review is focused on the energetic particle observations made from the Ulysses spacecraft during the period it spent at high latitudes above the streamer belt in 1999/2000. The relativistic electron intensity has exhibited a significant number of impulsive increases, which are attributed to solar flares, up to latitudes of S80° degrees. These…
The Solar and Cosmic-Ray Synodic Periodicity (1969 1998)
Rybák, J.; Kudela, K.; Antalová, A.
The synodic recurrence of the Mt. Wilson plage index (MPSI) and the Calgary cosmic ray (CR) intensity is investigated, using the wavelet power spectra in the range of 18 38 days, during the last three solar cycles. The unique temporal coincidence between the quasi synodic MPSI and the CR periods is detected in 1978 1982 (the 21st solar cycle). In …
Solar Wind Electron Observations Near Solar Maximum at High Latitudes From Thermal Noise Spectroscopy
Moncuquet, Michel; Issautier, Karine; Meyer-Vernet, Nicole +1 more
The Ulysses spacecraft is reaching high heliolatitudes during the approach to solar maximum. We show preliminary in situ electron observations from the URAP experiment, using thermal noise spectroscopy. This method is especially suited to measure accurately the electron density and thermal temperature. The data acquired in the period June Septembe…
Remote Sensing of H from Ulysses and Galileo
McComas, D.; Witte, M.; Pryor, W. +5 more
We model interplanetary H Lyman-α (Lα) observations from Galileo UVS (Ultraviolet Spectrometer) and EUVS (Extreme Ultraviolet Spectrometer) (Hord et al., 1992) and the Ulysses interstellar neutral gas (GAS) instrument (Witte et al., 1992). EUVS measurements near solar maximum (max) in 1990 1992 have a peaked brightness maximum upwind due to a rath…
Ion Acoustic Waves in the Heliosphere
Lin, Naiguo; Kellogg, P. J.; MacDowall, R. J. +1 more
Observations of ion acoustic waves in the solar wind during the first and second orbit of the Ulysses spacecraft are presented. The observations show variations of the wave activity with the heliolatitude and with the phase of the solar cycle. The interrelationships between the wave intensity and the electron heat flux and the ratio of electron to…
An Estimate of Drift Effects in Various Models of the Heliospheric Magnetic Field
Potgieter, M. S.; Burger, R. A.; van Niekerk, Y.
We use a comparison with other models to estimate how significant drifts will be in the Fisk model of the heliospheric magnetic field (HMF). We also show that drifts are still be present in an idealized field model for the period shortly after the solar polarity reversal.
Cosmic Ray Transport in a Heliospheric Magnetic Field with Non-Polar Coronal Holes
Jokipii, J. R.; Kóta, J.
The simple tilted dipole picture of Corotating Interaction Regions which prevailed during the first polar pass of Ulysses no longer applies since the Sun entered a more active phase. Recent observations show that CIRs still persist, though the large polar coronal holes of solar minimum shrink to smaller areas and move to lower latitudes. We presen…
Latitudinal Variation of the Underlying Heliospheric Magnetic Field Direction: Comparison of the Ulysses First and Second Orbits
Balogh, A.; Forsyth, R. J.; Smith, E. J.
We discuss the underlying direction of the heliospheric magnetic field measured by Ulysses in the latitude range 6° S-65° S by examining distributions of the magnetic field azimuthal angle with respect to the simple Parker spiral model. During the first Ulysses traversal of this latitude range in 1992 1994, while solar activity was declining, the …
26-day Analysis of Energetic Ion Observations at High and Low Heliolatitudes: Ulysses and ACE
Lario, D.; Forsyth, R. J.; Roelof, E. C. +1 more
We present observations of energetic (0.34 8 MeV) ions from the Ulysses spacecraft during its second ascent to southern high latitude regions of the heliosphere. We cover the period from January 1999 until mid-2000 as Ulysses moved from 5.2 AU and 18° S to 3.5 AU and 55° S. In contrast to the long-lived and well-defined ∼26-day recurrences that we…