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 sol ar radii from the Sun, by using several natural sources simultaneously, res ult 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 ge ometry is very close to that of the optical corona. Correlations between th e solar wind flow structure and magnetic field data were studied. It emphas izes 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 st reams far in the interplanetery space. (C) 1999 Elsevier Science Ltd. All r ights reserved.