2 days Ago By David Bressan, Senior Contributor
Global map showing gravitational variations caused by topographic changes. In purple higher features ..
. More like seamounts and in green lower features like rift zones. There are better maps of the Moon’s surface than of the bottom of Earth’s ocean.
Researchers have been working for decades to change that. As part of the ongoing effort, a NASA-supported team in collaboration with researchers from the French space agency CNES (Centre National d’Études Spatiales) recently published one of the most detailed maps yet of the ocean floor, using data from the SWOT (Surface Water and Ocean Topography) mission. Launched in December 2022, the SWOT satellite measures the height of water in lakes, reservoirs and rivers.
Researchers can use these differences in height to create a kind of topographic map of the surface of fresh- and seawater. This data can then be used for tasks such as assessing changes in sea ice or tracking how floods progress down a river. SWOT covers about 90 percent of the globe every 21 days, so the researchers used the additional data to map the world’s oceans.
Elevations like underwater mountains, having a larger mass and a stronger gravitational pull, slightly deform the sea surface above them. Previous ocean-observing satellites have detected massive versions of these bottom features, such as seamounts over roughly 3,300 feet (1 kilometer) tall. The SWOT satellite can pick up seamounts less than half that height, potentially increasing the number of known seamounts from 44,000 to 100,000.
“Abyssal hills are the most abundant landform on Earth, covering about 70 percent of the ocean floor,” explains Yao Yu , an oceanographer at Scripps Institution of Oceanography and lead author on the paper. “These hills are only a few kilometers wide, which makes them hard to observe from space. We were surprised that SWOT could see them so well.
” The improved view from SWOT also gives researchers more insight into underwater plate boundaries, a key element in Earth’s plate tectonics . The seafloor widens along rift zones, pushing the tectonic plates apart, and gets recycled into Earth’s mantle along subduction zones. The orientation and extent of geological features mapped by SWOT can reveal how tectonic plates have moved over time.
Rift zone in the Indian Ocean showing a parallel set of fracture zones and faults. The new seafloor map has also practical applications. Knowing the topography of the ocean floor is crucial for a range of seafaring activities, including navigation and laying underwater communications cables.
The researchers have extracted nearly all the information on seafloor features they expected to find in the SWOT measurements. Now they’re focusing on refining their picture of the ocean floor by calculating the depth of the features they see. The work complements an effort by the international scientific community to map the entire seafloor using ship-based sonar (hopefully) by 2030.
The study, " Abyssal marine tectonics from the SWOT mission ," was published in the journal Science. Additional material and interviews provided by Jet Propulsion Laboratory and NASA Earth Observatory ..
