In-situ observing system has provided the capability to monitor multi-decadal changes of salinity in the open ocean and on large scales. However, in-situ platforms are inadequate to monitor salinity changes in marginal seas and coastal oceans as well as salinity variations on mesoscales. Monitoring longer-term changes of salinity in these regions and scales are important to the studies of terrestrial-ocean water cycle linkage, cross-shelf exchanges, coastal-open ocean connection, energy transfer, and biogeochemistry. Satellite measurements of sea surface salinity (SSS) have demonstrated their values to enhance salinity observing capability in these regions and scales. This presentation highlights the accomplishments of satellite SSS, especially in studying salinity variations for regions and scales not well resolved by in-situ platforms. Examples will be provided to emphasize the synergy of satellite and in-situ salinity observing systems to investigate the linkage of open-ocean and marginal sea salinity in relation to longer-term changes in the climate and water cycle. Recognizing this need, the Global Climate Observing System (GCOS) Implementation Needs (Belward et al.2016) suggested Action 032: Ensure the continuity of space-based SSS measurements. Sustaining satellite SSS observing capability, enhancing spatial resolution, and improving accuracy (especially in high-latitude oceans) are important to studying the linkages of the ocean with the water cycle and climate variability.