Scientists Study Sea Surface Salinity

Aquarius is a focused effort to measure sea surface salinity and will provide the global view of salinity variability needed for climate studies. The mission is a collaboration between NASA and the Space Agency of Argentina. Launched June 10, 2011, aboard the Argentine spacecraft Aquarius/Satelite de Aplicaciones Cientificas (SAC)-D, Aquarius is NASA's first satellite instrument specifically built to study the salt content of ocean surface waters. Salinity variations, one of the main drivers of ocean circulation, are closely connected with the cycling of freshwater around the planet and provide scientists with valuable information on how the changing global climate is altering global rainfall patterns. 

The salinity sensor detects the microwave emissivity of the top approximately 1 inch (1 to 2 centimeters) of ocean water - a physical property that varies depending on temperature and saltiness. The instrument collects data in 240-mile-wide (386 kilometers) swaths in an orbit designed to obtain a complete survey of global salinity of ice-free oceans every seven days. Its instruments measure changes in sea surface salinity equivalent to about a "pinch" (i.e., 1/6 of a teaspoon) of salt in 1 gallon of water. By measuring sea surface salinity over the globe with such unprecedented precision, Aquarius answers long-standing questions about how our oceans respond to climate change and the water cycle. For example, monthly sea surface salinity maps give clues about changes in freshwater input and output to the ocean associated with precipitation, evaporation, ice melting, and river runoff. Aquarius data is also used to track the formation and movement of huge water masses that regulate ocean circulation and Earth's climate. The mission is led by principal investigator Dr. Gary Lagerloef of Earth & Space Research. Goddard Space Flight Center (GSFC) built and calibrated the highly accurate radiometers that are crucial for the detection of ocean salinity. Jet Propulsion Laboratory (JPL) designed and built the scatterometer that helps to minimize measurement errors due to sea surface roughness. JPL managed the mission until launch when GSFC assumed duty. Data processing, dissemination, and archiving tasks will be shared between GSFC and JPL.