Splintering Sea Ice in the Amundsen Gulf

Splintering Sea Ice in the Amundsen Gulf
Splintering Sea Ice in the Amundsen Gulf

During the winter months, much of the Amundsen Gulf in northern Canada is typically covered with fast ice—stationary sea ice that is “fastened” to the surrounding coastlines. However, the breakup of that ice tends to be rapid when the melting season arrives in spring.

The breakup was on full display in May 2023, when the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Aqua satellite captured this pair of images. On May 22 (left image), intact fast ice still covered much of the gulf. By May 30 (right image), an expanding series of cracks in the western part of the gulf had splintered that ice, leaving chunks of sea ice floating freely and drifting west into the Beaufort Sea. Patches of fast ice remained in the eastern part of the gulf in late May, but summer weather will ultimately clear it away as well. The Amundsen Gulf, the western entrance to the Northwest Passage, is usually ice-free by August.

“Winds played in important role in this breakup,” said Walt Meier, a senior research scientist at the National Snow and Ice Data Center. He noted that an area of low pressure centered south of the gulf prior to the breakup fueled strong easterly winds and large waves that broke up the ice and sent chunks of it drifting west. That event followed short-lived breakups in mid-March and mid-April that had already weakened the ice. “Back then, it was so cold that the ice started to regrow right away, but the ice that regrew was so thin that it was pre-conditioned to easily break up again later,” Meier said.

The timing of the spring breakup was earlier than usual, which matches the overall trend in the Beaufort Sea region in recent decades. However, the timing of the spring ice breakup in the Amundsen Gulf is known for being particularly inconsistent.

“Over a period of two decades, the Amundsen Gulf had the highest interannual variability of anywhere across the entire Northwest Canadian Arctic,” said Eleanor Wratten, a researcher at Northumbria University and the lead author of an analysis of decades of MODIS observations of fast ice in the Northwest Canadian Arctic. “We saw the timing of breakup change considerably from one year to the next, but the general pattern looked similar to what you see here. Ice usually remains in the southern bays the longest, with breakup veering toward the strait in the southeastern portion of the gulf.”

NASA Earth Observatory images by Allison Nussbaum, using MODIS data from NASA EOSDIS LANCE and GIBS/Worldview. Story by Adam Voiland.

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