Probe to Track Warming's Effects on Water

Hoping to untangle a key mechanism by which Earth warms and cools, a new satellite will for the first time make ongoing measurements of the saltiness of Earth's seas and the water content of the land.

The salinity of the oceans is believed to be responsible for pockets of cooler temperatures, particularly in the North Atlantic, though on a global scale the planet is warming, said Meric Srokosz with the National Oceanography Center in Southampton and a lead researcher on the new mission known as Soil Moisture and Ocean Salinity, or SMOS.

"You can get a local cooling effect," Srokosz told Discovery News. "It doesn't mean there's no global warming. Eventually the North Atlantic will also get warmer."

The goal of SMOS is to track the planet's water cycle, a task that has been spotty at best.

Ocean salinity, for example, affects water density and, in turn, ocean circulation, which transports heat from the planet's equatorial regions to the poles. Ocean salinity depends on several factors including rainfall, river runoffs, and the freezing and melting of polar ice.

"It's all part of the global water cycle. The oceans account for a large part of the operation," Srokosz said.

The satellite, which was launched Sunday night from Russia's Plesestk Cosmodrome, will fill in the large gaps in ocean data currently collected by ships and floating buoys.

"It's not a very dense coverage, said Srokosz. "The satellite will give you complete global coverage every few days."

SMOS, which is designed to last at least three years, will join an armada of spacecraft already in orbit monitoring Earth, information considered vital to assess human impacts on the planet and ultimately determine if efforts to curb warming trends are successful or not.

SMOS is expected to have a more immediate benefit as well. With ongoing soil moisture levels, scientists believe they will be able to better predict when flooding, mudslides and other potential disasters may occur.

"Being able to accurately measure the water available in the skin of the Earth helps us have a better understanding of the future weather," said Yann Kerr, the European Space Agency's lead researcher for the SMOS soil measurements. "Being able to forecast extreme events gives people time to escape."

The satellite works by measuring the temperature of microwaves reflected from the Earth's surface through 69 small antennas anchored into three deployable arms of the spacecraft. Unfolded, SMOS has a diameter of eight meters (26 feet).

Initially, SMOS will be used to obtain baseline measurements of salinity and soil moisture, but scientists would like to keep it running long enough to track any changes.