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Tracking the World's Water

After more than 20 years of research and development, the SMOS (Soil Moisture and Ocean Salinity) satellite was finally launched from Plesetsk, in northern Russia, on November 2nd, 2009. It will spend at least the next three years in orbit, monitoring the Earth's water.
The SMOS project, which originated at the Center for the Study of the Biosphere from Space (CESBIO)1 in Toulouse, aims to provide the first global maps of soil moisture and ocean salinity, two key indicators of the state of the Earth's climate.
“Getting the satellite into orbit has been the work of an international team,” says Yann Kerr, CESBIO's director and SMOS PI.



With its 69 antennae mounted on its three arms, the SMOS satellite will analyze the oceans' salinity and the soil's moisture.

The SMOS satellite acts as a giant radio-thermometer picking up the Earth's microwave radiation, which is reduced by soil moisture and salinity. The 69 antennae mounted on the satellite's three “arms” pick up radiation from large pseudo-hexagons approximately 1000 kilometers wide. “It lets researchers compile maps of our planet's surface water every three days with a resolution of 40 kilometers or better,” adds Kerr.
Since water levels, whether as soil moisture or in the oceans, are seen as “a tracer or an indicator of climate change,” the SMOS mission—a joint French, Spanish, and European Space Agency project—will not only let researchers track long-term climate change, but also predict it with greater accuracy in the short term.
This also means scientists can follow ocean currents as they move around the globe, and thus “better understand and model thermohaline circulation,” in other words, the way temperature and salinity interact.
Since its launch last November, SMOS has already started sending back data, which is promising for meteorologists, hydrologists, and agronomists. “All the first stages have gone marvellously well and we have received the first images earlier than anticipated,” Kerr says. “We're extremely satisfied.”

Tom Ridgway

Notes :

1. Centre d'études spatiales de la biosphère (CNRS / Université Paul Sabatier / CNES / IRD).

Contacts :

Yann Kerr,
CESBIO, Toulouse.


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