Barely recognizable at first glance, the continents can only be seen in outline. Because the star of the image is indeed him: the ocean.
Launched in December 2022 by NASA and the National Center for Space Studies (CNES), the SWOT satellite – an acronym for “topography of surface waters and oceans” – completed its first year of measurements taken from the sky. His “birthday card” is therefore logically a… topographical map!
The precious satellite data collected allowed researchers to study the natural borders between continents and, above all, to identify underwater mountains and volcanoes too small to be detected by previously launched satellites, report our colleagues from Live Science on December 12.
The surface of the ocean is not flat: bumps of water reflect what is on the bottom
With a resolution of 8 kilometers and a 21-day trajectory covering most of the planet, a single year of SWOT data provides a comprehensive picture “clearer” of the ocean floor than 30 years of data collected collectively by older ships and satellites, the researchers compared in the journal Science.
This new satellite actually measures the height of the ocean surface – which, “despite appearances, it is not flat”note our colleagues. By gravitational attraction, underwater reliefs accumulate above them a certain quantity of water which is organized into spreading humps. Variations in the height of the sea surface therefore reflect what lies at depth.
Scale: the Eötvös is a unit corresponding to a gravity gradient. By gravitational attraction, underwater reliefs accumulate above them a certain quantity of water which is organized into spreading humps. SWOT / NASA / CNES
On the map, we can thus distinguish the “abyssal hills”that is to say parallel ridges a few hundred meters high, formed by the movements of tectonic plates. The team was even able to spot several places where the direction of the ridges had changed – suggesting that at some point in Earth’s history, the tectonic plates changed course.
Underwater volcanoes revealed
We can also discern underwater mountains and volcanoes, whose presence influences ocean currents and which often constitute hotspots for biodiversity. By zooming in on the image, the scientists were able to count “several thousand small seamounts of less than 1,000 meters, previously unknown.”
“The discovery of these features will truly advance scientific developments, including theories of plate tectonics”Dr. Yao Yu, co-author of the study and geographer at the Scripps Institution of Oceanography, told popular science media.
Among the fields of research likely to experience immense advances thanks to this ultra-precise map are marine currents, the transport of nutrients in seawater, as well as the geological history of the Earth’s oceans. Quite a program!
