Evolution of the solar wind transition region over the epoch of solar activity minimum

Occultation studies of near-Sun plasmas at radial distances of 10 to 40 solar radii from the Sun, by using several natural sources simultaneously, result in large-scale patterns, radio maps of the solar wind flow. Large radio telescopes of the P.N.Lebedev Physical Institute, Pushino, were used. The 1995–1997 experiments showed that the evolution of the transition region geometry is very close to that of the optical corona. Correlations between the solar wind flow structure and magnetic field data were studied. It emphasizes the fundamental role of the magnetic fields at all stages of the solar wind acceleration, from subsonic flow close to the Sun up to supersonic streams far in the interplanetery space.