co-founder of Bedrock , a public benefit technology startup that is working toward a scalable , lower-cost system for nearshore , shallow-water hydrographic surveys ( 3D details ) of the ocean floor .
Tidal power , which harnesses energy from tides , requires similar knowledge . Carbon sequestration and hydrogen production ( by splitting seawater ) are also promising technologies that rely on the ocean . Exploring these energy alternatives without actually understanding what the ocean floor looks like is akin to flying blind . You cannot afford to make mistakes when time is of the essence — the United Nations ’ Global Sustainable Development Goals have a target date of 2030 .
HARNESSING THE RISING TIDES OF TECH Hydrographic surveys , which detail the seafloor , have evolved over decades . In the 19th century , the best maps of the seafloor came from what are known as sounding lines . Just as an echo in a valley rebounds , acoustic systems sent sound down to the ocean floor and recorded the time it took to reach the bottom and back . Measuring the different times at different distances gave a rough idea of the features ( mountains , valleys , etc .) of the ocean floor .
GPS satellites came later . But tracing the details of the seafloor using satellites is like figuring out the details of a moving airplane with the naked eye . “ It is really only a gross topography ,” says Dr . Charles Paull , a senior scientist at the Monterey Bay Aquarium Research Institute ( MBARI ), a center for ocean research and technology development in Monterey , California . He indicates that the resultant maps were mostly rough sketches . “[ They do ] not provide enough detail at resolution to be able to understand the seascape and what it might look like or the processes that formed it ,” Paull says .
Early maps served their purpose for maritime navigation , but addressing climate change will demand more rigor in seafloor mapping .
Multibeam sonar techniques are huge improvements . They send out many sonar beams — in a fan shape — that cover the ocean a lot faster . They have a downside , however . High-frequency sonar beams are dulled by water . “ The ocean is a really harsh environment ,” says DiMare . “ Different layers of the ocean will have different salinities that will bend the sound in different ways . You have to understand the chemical layers the sound has to pass through .” To bypass these headaches , instead of shooting sonar beams from the ocean ’ s surface down to the depths , researchers are launching autonomous vehicles from the surface into the water , bringing the mapping apparatus as close to the ocean floor as possible .
MBARI , for example , launches autonomous underwater vehicles ( AUVs ) on programmed missions from small ships . MBARI concentrates on collecting extremely high-resolution ( 1m x 1m ) maps of small patches of the ocean floor . These surveys are used
“ [ GPS satellite maps do ] not provide enough detail at resolution to be able to understand the seascape and what it might look like or the processes that formed it .”
— Dr . Charles Paull , senior scientist , Monterey Bay Aquarium Research Institute
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