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Title:Underwater tsunamis created by glacier calving cause vigorous ocean mixing

Scientists on a research vessel in Antarctica watched the front of a glacier disintegrate and their measurements "went off the scale." As well as witnessing disruptions on the ocean surface, they recorded "internal" underwater tsunamis as tall as a house, a phenomenon that has been previously missed in the understanding of ocean mixing and in computer models. The team, led by British Antarctic Survey (BAS) researchers, report their observations today in the journal Science Advances.

Internal tsunamis are an important factor in ocean mixing, which affects life in the ocean, temperatures at different depths, and how much ice the ocean can melt. Ice in Antarctica flows to the coast along glacier-filled valleys. While some ice melts into the ocean, much breaks off into icebergs, which range in size from small chunks up to the size of a country.

A team on board the BAS research ship RRS James Clark Ross was taking ocean measurements close to the William Glacier, situated on the Antarctic Peninsula, as the front of it dramatically disintegrated into thousands of small pieces.

The William Glacier typically has one or two large calving events per year, and the team estimated this one broke off around 78,000 square meters of ice - around the area of 10 football pitches - with the front of the glacier towering 40 meters above sea level.

Before it broke away, the water temperature was cooler at around 50-100 meters in depth, and warmer below this. After the calving, this changed dramatically, with temperature much more even across different depths.

Lead author of the study Professor Michael Meredith, head of the Polar Oceans team at BAS, said, "This was remarkable to see, and we were lucky to be in the right place at the right time. Lots of glaciers end in the sea, and their ends regularly split off into icebergs. This can cause big waves at the surface but we know now it also creates waves inside the ocean. When they break, these internal...

Organization:PHYS.ORG - Earth
Date Added:11/24/2022 6:37:35 AM