Corotating shock accelerated particles guided by wavy spiral magnetic fields in the solar wind at high heliographic latitudes

Abstract

We propose the persistent presence of randomly fluctuating, large‐amplitude, long‐timescale wavy spiral magnetic fields in the solar wind at all heliographic latitudes. These Alfvénic fluctuations can be generated by gradual evolution of solar coronal holes or by interplanetary Kelvin‐Helmholtz instabilities occurring around the two conical interfaces at ∼±30° where strong wind shears appear quasi‐periodically during the solar minimum. Using this scenario, we offer interpretations for several recent high‐latitude observations of quasi‐periodic (i.e., ∼26.6 days) energetic particle and cosmic ray modulations from Energetic Particle Composition instrument and Cosmic Ray and Solar Particle Investigation sensor systems aboard Ulysses spacecraft.

Propagation of three‐dimensional Alfvén waves in a stratified, thermally conducting solar wind

“…As a result of recent high-latitude observations from the Ulysses spacecraft on the properties of the fast (h 700 km s -x) solar wind arall et al, 1996] [Parker, 1958[Parker, , 1963[Parker, , 1991. In particular, these transverse magnetic [An et al, 1989Hollweg, 1990Hollweg, , 1996Barkhudarov, 1991;Barnes, 1992;Similon and Zargham, 1992;Musielak et al,, 1992;Velli, 1993;Lou, 1992Lou, , 1993aLou, , b, 1994aLou, , b, 1995Lou, , 1996Rosner et al, 1991;Lou and Rosner, 1994;MacGregor and Charbonneau, 1994;Krogulec et al, 1994;Lau and Siregat, 1996]. Nevertheless, while an enormous literature has grown on this subject, the theoretical details of exactly how this wave acceleration process takes place, and how it relates to the presence of solar high speed wind streams, remain uncertain.…”

Bursty synchrotron intensity variations of Jovian 6-cm radio emissions and Jupiter's quasi-periodic polar activities

“…Jupiter is known to be an important planetary source of relativistic electrons to populate the entire heliosphere (e.g. Nishida 1976;Lou 1996). As the Jovian magnetic field points towards its south pole, out-streaming extremely relativistic electrons gyrate around south field lines with very small pitch angles and emit low-frequency (ν < ∼ 0.7 MHz) beamed radio bursts with partially right-hand circular polarizations (MacDowall et al 1993;Lou 2001a;LZ).…”

Untitled

“…Here, we present a scenario of random-phased wavy spiral magnetic fields (over a wide frequency range) in the solar wind (see Fig. 10 and Lou, 1996) and explain in physical terms how global solar modulation of cosmic rays and energetic particles works. For a detailed analysis of wavy spiral magnetic fields, one is referred to Lou (1994) on Alfvénic fluctuations in the solar wind with a mean spiral magnetic field.…”

“…The mean spiral magnetic field is roughly perpendicular to the radial solar wind and thus cannot suppress such KH instabilities. As a result, large-amplitude Alfvénic fluctuations with low frequencies and long azimuthal wavelengths in spiral magnetic fields can be sustained along the interfaces by periodically varying shears in solar wind speeds (Lou, 1996). In particular, magnetic field fluctuations should be stronger along those portions associated with CIRs because of stronger shears.…”