A NASA-sponsored expedition will sail to the North Atlantic's saltiest spot to get a detailed, 3-D picture of how salt content fluctuates in the ocean's upper layers and how these variations are related to shifts in rainfall patterns around the planet.
The research voyage is part of a multi-year mission, dubbed the
Salinity Processes in the Upper Ocean Regional Study (SPURS), which will deploy multiple instruments in different regions of the ocean.
The new data also will help calibrate the salinity measurements NASA's Aquarius instrument has been collecting from space since August 2011.
SPURS scientists aboard the research vessel Knorr leave Sept. 6 from the Woods Hole Oceanographic Institution in Woods Hole, Mass., and head toward a spot known as the Atlantic surface salinity maximum, located halfway between the Bahamas and the western coast of North Africa.
The National Oceanic and Atmospheric Administration and the National Science Foundation also support the expedition.
The researchers will spend about three weeks on site deploying instruments and taking salinity, temperature and other measurements, before sailing to the Azores to complete the voyage on Oct. 9.
They will return with new data to aid in understanding one of the most worrisome effects of climate change-the acceleration of Earth's water cycle. As global temperatures go up, evaporation increases, altering the frequency, strength, and distribution of rainfall around the planet, with far-reaching implications for life on Earth.
"We will investigate to what extent the observed salinity trends are a signature of a change in evaporation and precipitation over the ocean versus the ocean's own processes, such as the mixing of salty surface waters with deeper and fresher waters or the sideways transport of salt," said Eric Lindstrom, physical oceanography program scientist at NASA Headquarters in Washington.
To learn more about what drives salinity, the SPURS researchers will deploy an array of instruments and platforms, including autonomous gliders, sensor-laden buoys and unmanned underwater vehicles. Some will be collected before the research vessel heads to the Azores, but others will remain in place for a year or more, providing scientists with data on seasonal variations of salinity.
Some of the devices used during SPURS to explore the Atlantic's saltiest spot will focus on the outer edges of the study area, travelling for hundreds of miles and studying the broadest salinity features. Other instruments will explore smaller areas nested inside the research site, focusing on smaller fluxes of salt in the waters.
The suite of ocean instruments will complement data from NASA's salinity-sensing instrument aboard the Aquarius/SAC-D (Satelite de Aplicaciones Cientificas-D) observatory, and be integrated into real-time computer models that will help guide researchers to the most interesting phenomena in the cruise area.
"We'll be able to look at lots of different scales of salinity variability in the ocean, some of which can be seen from space, from a sensor like Aquarius. But we're also trying to see variations in the ocean that can't be resolved by current satellite technology," said David Fratantoni, a physical oceanographer with Woods Hole and a member of the SPURS expedition.
The 2012 SPURS measurements in the North Atlantic will help scientists understand the behaviour of other high-salinity regions around the world.
A second SPURS expedition in 2015 will investigate low-salinity regions where there is a high input of fresh water, such as the mouth of a large river or the rainy belts near the equator. (ANI)