From space, SWOT maps our water reserves with unparalleled precision

Scientists always have eyes that light up when they talk about the space missions they’re working on. For SWOT (Surface Waters in Ocean Topography), which is currently holding its first team meeting in Toulouse with hundreds of participants, the excitement is complete.

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“The satellite and the SWOT system are working so well that it exceeds all our expectations!”, confirms Rosemary Moreau, principal scientific researcher in oceanography for the SWOT project at LEGOS (1) in Toulouse. The oceanographer already knows that she will be able to “better monitor currents and levels, to ultimately understand the mechanism of the water cycle. These observations are crucial in the context of climate change.”

For study models to be effective, experts need data. The SWOT satellite, developed by NASA and the French National Center for Space Studies on a three-year mission, aims to provide high-resolution maps of the planet’s fresh water resources as well as the effects of rising sea and ocean levels. The first results provide unprecedented accuracy, ten times greater than the altimetry data provided by current satellites. Thanks to SWOT, 90% of the water on Earth can be measured.

Measured sizes of waterways less than 50 meters wide

In hydrology, strengths, weaknesses, opportunities and threats go beyond the stated definition of 100-metre-wide watercourses. As evidence of this, the first radar image (KaRIn instrument) of the Toulouse area, taken in January 2023, logically shows the 200-metre-wide Garonne River, but also to the south, the 50-metre-wide Ariege River and, more unexpectedly, the Canal du Midi which… Its width reaches 20 metres. SWOT is able to measure heights and volumes. “We did not think we could reach this level of precision. I have observed the same thing on small mountain lakes in the Pyrenees whose sizes we will be able to study. We have taken a step forward and all scientists are waiting for this data,” explains Jean-François Creto. , from the French National Center for Space Studies, Deputy Director of LEGOS (1), Principal Investigator of the SWOT mission.

“When we launched nine months ago, we knew we were witnessing an important moment in science. SWOT will help set new standards. We are not only testing new technologies, we are gaining advanced knowledge of the water cycle, a vital component of our survival.” “, confirmed Nadia Vinogradova, responsible for the SWOT scientific program at NASA.