Salinity Remote Sensing and Results from the Aquarius Satellite Mission

Conceived in the late 1990s, and proposed to NASA’s Earth System Science Pathfinder (ESSP) Missions program in 2001-2002, the Aquarius mission was selected to resolve missing physical processes that link the water cycle, the climate, and the ocean by measuring sea surface salinity (SSS). The satellite was developed in partnership with Argentina as the joint Aquarius/SACD mission, and included complementary sensors provided by Argentina, Italy, France and Canada. The primary salinity sensor, Aquarius, provided global coverage every 7 days at 150 km spatial resolution for more than three years to resolve the global mean, seasonal and interannual variability. This presentation will provide a brief summary of the physics underlying the microwave remote sensing measurement of ocean surface salinity by, and a survey of the scientific results from Aquarius. Using both Aquarius and SMAP data, the SSS variations during 2015/16 El Nino are being analyzed. We also note anomalously high SSS in the western equatorial Pacific during the recent El Nino mature phase. While the scientific focus was basin-scale, the capability to resolve smaller scale features exceeded expectations; such as tropical instability waves, river plumes and ocean fronts. Other key science achievements include improving tropical Pacific SST forecast skill, linking SSS changes to terrestrial rainfall, estimating total alkalinity, and discovering the range of temporal variability of the SSS field.. NASA’s support of ocean salinity research will continue through the Ocean Salinity Science Team (OSST), and satellite salinity observations are ongoing with NASA’s SMAP and ESA’s SMOS missions.