SOLARNET Conference: The Many Scales of the Magnetic Sun

Variations of the solar magnetic field are the main sources of several manifestations of the solar activity (e.g. flares, CMEs, solar wind). A way to quantify such variations is by means of a physical index, the Ca II K index, which has been proven to be a great proxy for the line-of-sight unsigned magnetic flux density along all phases of the cycle, and not only when sunspots are present.
In this respect, an assessment of the long-term behaviour of the solar wind is of paramount importance to understand the nature of its relationship with the global magnetic field of the Sun and with its cycle-to-cycle variations. Here, we study the variations of physical proxies of the solar activity (i.e. Ca II K index, Mg II index), on solar cycle time-scales, and how they are related to variations of solar wind parameters. The available time series allow to evaluate this relation over the last five solar cycles (from 1965 to now).
By adopting a climatological approach, the results show that there is a delayed response of the solar wind with respect to the solar activity, but such response is not the same for the different solar cycles. The analysis offers the possibility to deepen the understanding of the processes that link the global dynamo to solar variability and to the properties of the solar wind near the Earth.