A Southern Ocean research expedition has mapped seamounts that string through and help shape the Antarctic Circumpolar Current.
Mapping Submarine Volcanoes in the Antarctic
Novel high-resolution seafloor maps between Antarctica and Tasmania show an underwater volcano chain with towering peaks that could sculpt the currents of the ocean above. These submarine volcanoes sit 4,000 meters below the ocean waves and are right in the path of Earth's strongest ocean current, known as the Antarctic Circumpolar Current. This strong current has a clockwise flow around Antarctica and serves as a barrier that helps the continent remain frozen.
Scientists have now been able to map a specific region where the barrier is leaking. This leaking allows warm water swirls to reach Antarctica shores.
Benoit Legresy, the mapping expedition's chief scientist and a sea level scientist from the University of Tasmania, explains that the area is a gateway where heat gets funneled to Antarctica. This contributes to the melting of ice and the rising of sea levels.
While the leak apparently is not new, the scientists are hopeful that the novel map could aid with predictions pertaining to the leak's evolution as oceans get warmer because of climate change and meltwater surges into the Southern Ocean.
The team gathered ocean data within the current from the Australian research vessel "Investigator." They also made use of the new Surface Water and Ocean Topography (SWOT) satellite of NASA and the French National Center for Space Studies. The SWOT gauges ocean surface height from space in order to glean what lies under.
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Chain of Ancient Seamounts
The satellite measurements shed light on a mountain chain in the area of the survey. This spanned 20,000 square kilometers in an area by Macquarie Island and Macquarie Ridge's west.
Christopher Yule, marine geophysics doctoral student from James Cook University who participated in the expedition, explains that they were able to discover a remarkable chain of ancient submarine volcanoes that comprises eight volcanoes that have remained dormant for long periods of time. These long-dormant mounts have a peak of 1,500 meters, with one having a double vent. Yule adds that four of the seamounts were new to the world of science.
The formation of the volcanoes took place within the last 20 million years. It is likely that they play a crucial role when it comes to shaping the currents that surround Antarctica.
Helen Philips, a co-chief scientist of the expedition and an oceanography associate professor from the University of Tasmania, explains that the Antarctic Circumpolar Current is able to "feel" the seafloor and the mountains within its path. Where it meets barriers, such as seamounts or ridges, it creates wiggles in the flow of water. These wiggles then form eddies, or currents that are circular and that pinch off the currents of the ocean. These eddies are like ocean weather systems that play a crucial role in transporting carbon and heat from the upper ocean down into deeper layers.
Understanding the sea floor's depth and shape is important to quantify the undersea mountain, valley, and hill influence on the heat leak towards Antarctica and the Antarctic Circumpolar Current.
Overall, mapping the area will offer clues regarding the ice melt levels in Antarctica and aid in predicting sea level rises.
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