Invited speakers: Sean Bruinsma, Ilaria Ermolli, Michael Lockwood, Sandrine Rochel-Grimald

Geomagnetic and Solar indices are extremely important for understanding the variations of solar and terrestrial parameters for times when no direct observations are available. These indices, which inherit the knowledge accumulated during more than one century of continuous observation and are now easily available, allow us to study in detail the physical coupling between the solar and cosmic energy input (solar wind, solar irradiance, cosmic rays) and the Earth’s ionized and neutral environment.

This session is devoted to discuss both the current state-of-the-art of indices time-series as well as studies that use these indices to understand the coupling between solar activity and the variation of our space environment. Of particular importance will be to discuss the detailed physics that explain the assets and limitations of the indices, as well as their discrepancies with other indices or parameters.

Contributions discussing the latest developments and inter-calibration of indices and the contributions of indices to our understanding of space climate and space weather are welcome. We encourage contributions related to the European COST ES 1005 action TOSCA. The multidisciplinary perspective of this session is intended to strengthen the dialog between the solar and geomagnetic communities.