The major goal of the 'Satellite & In Situ Salinity (SISS) Working Group: Understanding Stratification and Sub-Footprint Processes' is to improve our understanding of the link between L-band satellite (SMOS and Aquarius) remotely sensed salinity (for approximately the top 1 cm of the sea surface) and in situ measured salinity (routinely measured at a few meters depths by ships and ARGO floats but recently accessible to up to few cm depth by new profilers, and by surface drifters ...) and to develop practical methodologies for relating satellite salinity to other estimates of sea surface salinity.