Solar wind responses to the solar activity cycle Original Research Article

The solar magnetic field and the plasma properties, such as the temperature and density distributions in the solar corona, determine the solar wind stream structure and the extent and dynamics of the entire heliosphere, including its global magnetic field. The variation of the solar wind (coming in the form of steady fast streams, variable slow flows and transient fast mass ejections) in response to solar activity over the whole cycle is reviewed in detail. Emphasis is placed on the observed and inferred changes of the plasma states in the closed corona (streamers, loops) and open corona (funnels, holes), and on the evolution of the coronal and interplanetary magnetic field on all scales. The resulting three-dimensional structure of the solar wind and the evolution of the inner heliosphere over the solar cycle are discussed. The variations of the solar wind ram pressure and consequent variations of the global heliosphere are briefly addressed.