Science & Technology

The tide becomes stronger as the Arctic ice melts

In the Canadian Arctic Archipelago (CAA), tide strength in the Kitikmeot Sea is more related to sea ice coverage than previously thought or observed in neighboring areas. This new understanding of the relationship between sea ice and tides from a year’s worth of ocean monitoring and state-of-the-art tidal modeling provides a high tide season as climate change lengthens the ice-free season in this region of the Arctic. It can become long and cause a feedback loop of sea ice melting.

“At Kitikmeot, seasonal sea ice reduces tide heights and currents by about 50%,” he explained. Lina M. RotermandHe is an oceanographer and senior researcher at the project at Dalhousie University in Halifax, Nova Scotia. “The longer the ice-free period, the longer the period of stronger tides and the shorter the period of low tides.”

Melted ice leads to stronger tides

The sea freezes on ice in the Arctic winters and melts in the Arctic summers. This cycle may seem simple at first glance, but it is only one element of the seasonal change in the cryosphere. “Every winter, sea ice reduces the tides,” said Rotermand. In the Arctic and other regions, tides can bring both nutrients and heat from the ocean floor to the surface of the water, thus playing an important role in marine dynamics and ecosystems. Too, they regulate the production of sea ice.

The sea ice in the Kitikmeot region of the Canadian Arctic Islands (CAA), highlighted in orange on this map, is more affected by the Atlantic tides than the sea ice in other parts of the CAA. The Victoria Strait, where Atlantic currents enter the region, is a water cove between Iqaluktuuttiaq (Cambridge Bay) and Talurjuaq (Spence Bay) north of Uqsuqtuuq (Gjoa Haven). Click to enlarge. credit: Maximilian Dörrbecker (Chumwa), CC BY-SA 2.5

The connection between sea ice and tide Studied before Some areas of the CAA have less focus on Kitikmeot, she said. “In some areas, sea ice causes strong seasonal changes in tides, and in others, the impact is negligible.” Despite this relationship, most computer models of sea ice growth are of Arctic ice. It does not take into account the role that sea ice plays in adjusting position, thickness, concentration, and movement.

To better understand the relationship between sea ice and tides, researchers collected a year’s worth of tidal data from the Dease Strait in the Kitikmeot Region (just west of Ikarkututtiak, also known as Cambridge Bay). Year. From those data, they found that winter tides were 50% to 60% shallower and 65% slower than summer tides. They used these data to help build a high-resolution tidal model for the entire Kitikumeo region, including many narrow and shallow straits. They investigated whether the tides were widespread in winter and what it was about sea ice to dry those tides.

“Strong tidal dissipation in the Victoria Strait region leads to smaller tides in the Kitikmeot region in both summer and winter,” said Roternund. The Victoria Strait is an important passage for Atlantic tides to enter the Kitikmeot Sea. Moreover, the model showed that: “In winter, sea ice friction and blockages of sea ice formed by thick, rough sea ice in the Straits of Victoria. [cause] Additional winter tide dissipation. Researchers validated the model using tide readings collected across the region.These results are Release In Journal of Geophysical Research: Oceans During April.

Can climate change cause a feedback loop?

“Tide mixing can bring subsurface heat to the surface and contribute to the melting of ice.”

The dual seasonal cycle of sea ice and tides can be out of balance due to the additional melting of sea ice caused by human initiative. Climate change.. “The less sea ice, the longer the season of strong tides,” says Roternund. “But it’s not the high tides that can complete the feedback loop, but the strong tides. Strong tides lead to more. [vertical] Tide mixing especially in shallow water. In winter in the Arctic, the sea level is colder than the bottom water. Therefore, tidal mixing can bring subsurface heat to the surface and contribute to the melting of ice. Therefore, a decrease in sea ice can lead to stronger tides, which in turn can lead to further reductions in sea ice.

“In the eastern Arctic, recent tidal intensifications have already brought more heat than usual from inside the ocean to the surface, melting more sea ice and setting up a strengthening cycle.” And a marine scholar at the University of Alaska Fairbanks Igor Polyakov Said Hakai Magazine During September. “Such studies are very important and useful because the effects of tides on the Arctic Ocean and ecosystems are often understated.” Polyakov was not involved in this study.

Feedback loops between sea ice and tides can play a much larger role than expected Some areas.. “In the Kitikmeot region, tides decrease by about 50% from summer to winter,” says Rotermand. [the reduction] Is about 25%, and in the Arctic Archipelago in eastern Canada it is about 5% to 10%. “

In the future, she said, the differences between these regions need to be better explained in the sea ice model. Arctic tide.. Researchers continue to monitor the tide, Sea ice At Kitikmeot, we plan to investigate how strong tides over a longer period affect formation. Polinias (Permanent open waters in otherwise ice-dominated areas) and their impact on marine ecosystems.

— Kimberly MS Cartier (@AstroKimCartier), Staff writer

Quote: Cartier, KMS (2021), Arctic sea ice melts and tides get stronger, Eos, 102, Published on October 21, 2021.
Text © 2021. AGU. CC BY-NC-ND 3.0
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The tide becomes stronger as the Arctic ice melts The tide becomes stronger as the Arctic ice melts

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