Friday, June 14, 2024

Melting Sea Ice Swirls off Greenland's East Coast | NASA Terra Earth Satellite

Melting Sea Ice Swirls off Greenland's East Coast | NASA Terra Earth Satellite

A satellite view of sea ice. The ice is white and solid at top left, while the edges swirl and swoop through the dark blue water.
Annotated/labeled version

Floating fragments of sea ice spun into intricate patterns as ocean currents carried them south along Greenland’s east coast in spring 2024. The Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite captured a moment of this dizzying journey on June 4, 2024.

Much of the ice has likely drifted a great distance to get to this point. The Fram Strait, a 450-kilometer (280-mile)-wide passage between Greenland and Svalbard (to the north, out of view), connects the Arctic Ocean with the Greenland Sea. It serves as the primary route for sea ice out of the Arctic. After moving through the Fram Strait, ice is swept south along the Greenland coast by the East Greenland Current.

Along the way, it breaks into smaller pieces and starts to melt in warmer ocean waters. “The smaller the floes, the more ‘wispy’ the patterns,” said Walt Meier, a sea ice scientist at the National Snow and Ice Data Center (NSIDC). The small ice fragments in those swirling patterns may only be meters or tens of meters across, he said—too small to distinguish in MODIS imagery. The aggregation of small pieces imparts the look of hazy, smoke-like curls to the surface of the water.

The predominant southward current along the coast gets perturbed by the jagged coastline, other offshore currents, and occasionally winds coming off the Greenland Ice Sheet, said Meier, forming eddies that are made visible by the ice chunks. “With the thinning and breaking up of the ice, it becomes more easily pushed around by the winds and current,” he said.

Larger floes appear closer to the shoreline. This ice is likely more local in origin, breaking off from the fast ice and becoming entrained in the swirling waters. Fast ice, anchored to the shore or shallow ocean bottom, is visible at the top of the image and along other sections of the coast.

As the summer wears on, ice will continue to drift out of the Arctic. However, in recent years, more of the Arctic Ocean’s sea ice has become too young and thin to make the journey south, noted Angela Bliss, a sea ice scientist at NASA’s Goddard Space Flight Center. “Historically, when more of the Arctic sea ice would survive the summer melt season, growing thicker and older, a larger volume of sea ice would be transported through the Fram Strait,” she said.

Climate scientists are watching this diminished flow closely. The movement of sea ice and freshwater out of the Arctic is a component of ocean circulation patterns that distribute heat around the planet. The so-called “global ocean conveyor belt” transports cold water south and warm water north, contributing to climate conditions worldwide. “Less ice and freshwater transport have big implications for ocean productivity, as well as warming upper ocean temperatures, in the region,” said Bliss.

A 2023 study looking at two decades of ocean-mooring observations found that the East Greenland Current is moving less sea ice through the Fram Strait, primarily due to sea ice thinning. The researchers observed that summertime surface water temperatures off Greenland have risen, in part due to the increased presence of heat-absorbing open water. The water column has also become less stratified, making more nutrients available to phytoplankton communities.

Image Credit: NASA/Wanmei Liang, using MODIS data from NASA EOSDIS LANCE and GIBS/Worldview

Story Credit: Lindsey Doermann

Image Date: June 4, 2024

Release Date: June 13, 2024

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