Solar Activity Cycle in Solar-wind Sources and Flows

Experiments based on multi-source radio occultation measurements of the circumsolar plasma at R∼4.0−70R _S were carried out during 1997 – 2008 to locate the inner boundary of the solar-wind transonic transition region, R _in. The data obtained were used to correlate the solar-wind stream structure and magnetic fields on the source surface (R=2.5R _S) in the solar corona. The method of the investigation is based on the analysis of the dependence R _in=F(|B _R|) in the correlation diagrams, where R _in is the inner boundary of the solar-wind transition region and |B _R| is the intensity of the magnetic field at the source surface. On such diagrams, the solar wind is resolved into discrete branches, streams of different types. The analysis of the stream types using a continuous series of data from 1997 to 2008 allowed us to propose a physical criterion for delimiting the epochs in the current activity cycle.