Activité solaire et forçage climatique
Thierry Dudok de Wit
Over 99.99% of the energy input to the terrestrial environment comes from solar radiation, and yet the impact of solar variability on long-term changes remains a highly controversial issue. Direct radiative forcing is the most studied mechanism but other much weaker ones can have a significant leverage. Interestingly, these mechanisms have direct astrophysical relevance and much still remains to be learned by viewing the Sun as a star. In this presentation I shall briefly review the main mechanisms by which solar variability affects the Earth, and put them in a more astrophysical context.
Tomography of the solar photosphere from Hinode observations
M. Faurobert, Cl. Aime, G. Ricort.
(Université de Nice)
We have used Hinode/SOT spectroscopic observations in the magnetic sensitive lines of FeI at 602 nm to explore the depth variations of solar photospheric structures. A cross-correlation method between images obtained out of disk center at different line widths allows us to measure with a high accuracy the depth differences between the images. As an example we show that the altitude of the region where the contrast inversion of the granulation takes place is derived and compared to model predictions.