Speaker
Description
Solar irradiance is the fundamental energy source powering the Earth system, and its variability over time is a critical factor in understanding climate dynamics. While Total Solar Irradiance (TSI) represents the overall energy output, it is the wavelength-dependent variability of Spectral Solar Irradiance (SSI), especially in the ultraviolet, that most directly influences atmospheric processes.
Solar output fluctuates on a vast range of timescales, from milliseconds to millennia, driven by processes from turbulent convection to the slow evolution of the Sun itself. However, assessing variations beyond the well- documented 11-year solar cycle presents a significant observational challenge. Space-based measurements rarely extend beyond a decade, making the construction of a reliable long-term irradiance record critically dependent on the precise intercalibration of data from successive and diverse missions. Reconstruction becomes even more complex when relying on sparse data from historical telescopic observations. To reconstruct TSI/SSI over millennial timescales, estimates of the open solar magnetic field are indispensable. Such TSI and SSI reconstructions rely on cosmogenic isotopes, which act as proxies for cosmic ray intensity. Cosmic rays, in turn, are modulated by the heliospheric magnetic field, reflecting variations in solar activity.
This presentation aims to synthesize key aspects of solar variability and present the latest state-of-the-art findings, reflecting the community’s ongoing efforts to reconstruct this complex dataset.