Variations of the solar-wind stream structure in the region of subsonic flow during the 11-year solar cycle

Abstract

The large-scale stream structure of the solar wind near the Sun and its evolution during the 11-year solar activity cycle are investigated. The study is based on observations of scattering of the radiation from compact natural radio sources at radial distances R≤14RS (RS is the solar radius). Regular observations were conducted in 1981–1998 on the RT-22 and DKR-1000 radio telescopes of the Russian Academy of Sciences at Pushchino, at λ=1.35 cm and 2.7 m, respectively. The radial dependences of the interplanetary scintillations m(R) and the scattering angle 2ϑ(R) are considered together with the structure of large-scale magnetic fields in the solar corona at R=2.5RS. The entire range of variations in the level of scattering and the associated heliolatitude flow structures in the subsonic solar wind forms over the 11-year solar cycle, as a direct result of the large-scale structure of the evolving magnetic fields at the source of the solar-wind streamlines.