Earth observation model showing variations in sea surface salinity from December 2011 to December 2012. These data were collected by the Aquarius spacecraft. Salinity is colour-coded from low (dark blue) to high (red), with green showing the average salinity of 35 PSU. Salinity affects the circulation of water around the world's oceans, as water density increases with salinity. Also, the ability of seawater to dissolve carbon dioxide falls with increasing salinity. Hence, understanding salinity changes is an important component in the study of climate change. Inland seas, the Red Sea and the Gulf are not measured here. Aquarius is a NASA instrument on board the SAC-D satellite, operated by the Argentinian space agency CONAE (National Space Activities Commission).