The Power of Sea Salt - presented by Science at NASA.
On Friday, June 10th, when a Delta 2 rocket blasted off from California's
Vandenberg Air Force Base, rumbling into a morning-blue sky atop a column of
white smoke, some onlookers felt they could smell a hint of salt among the
rocket's exhaust.
Was it spray from the nearby Pacific Ocean? Or something to do with the payload
itself? That rocket was carrying a sensor named "Aquarius" on a mission to map
the salt in our planet's seas.
Researchers suspect that the salinity of Earth's oceans has far-reaching effects
on climate, much as the salt levels within our bodies influence our own delicate
internal balance. This is why the Aquarius mission is so important.
"Based on decades of historical data gathered by ships and buoys, we know the
salinity of Earth's oceans has changed over the last 40 years," says Aquarius
principal investigator Gary Lagerloef, a scientist at the Seattle-based
independent laboratory Earth and Space Research. "Something fundamental must be
happening to the water cycle."
In some regions, like the subtropical Atlantic, salinity is increasing, which
means more fresh water is being lost through evaporation at the sea surface. But
no one knows why this is happening; nor can anyone pinpoint why other areas are
experiencing more rainfall and lower salinity. To solve the mystery, scientists
need a comprehensive look at the ocean's salt content.
Within a few months, Aquarius will collect as many sea surface salinity
measurements as the entire 125 year history record from ships and buoys.
Circling Earth onboard Argentina's SAC-D satellite, Aquarius is one of the most
sensitive microwave radiometers ever built, and the first NASA sensor to track
ocean salinity from space.
"It can detect as little as 0.2 parts salt to 1,000 parts water - about the same
as a dash of salt in a gallon of water. A human couldn't taste such a low
concentration of salt, yet Aquarius manages to detect it while orbiting 408
miles above the Earth," says Lagerloef.
Salinity, along with temperature, governs the density of seawater. The saltier
the water, the denser it becomes. Density, in turn, drives the currents that
move heat around the planet.
"For example," says Lagerloef, "the Gulf Stream carries heat to higher latitudes
and moderates the climate. When these currents are diverted by density
variations, weather patterns such as rainfall and temperature change."
Could salinity be prompting such changes? For answers, researchers look to the
sky. Aquarius, they hope, will soon reveal the power of sea salt.
For more salty tales of Earth science, please visit science.nasa.gov.
Uploaded by ScienceAtNASA on Jun 16, 2011
Visit http://science.nasa.gov/science-news/science-at-nasa/2011/07jun_aquarius/
for the full story.
Документальный фильм "Power of Sea Salt"
