A warming climate is causing a decline in sea ice in the Arctic Ocean, where loss of sea ice has important ecological, economic and climate impacts. On top of this long-term shift due to climate change are weather events that affect the sea ice from week to week.

The strongest Arctic cyclone ever observed poleward of 70 degrees north latitude struck in January 2022 northeast of Greenland. A new analysis led by the 91Ě˝»¨ shows that while weather forecasts accurately predicted the storm, ice models seriously underestimated its impact on the region’s sea ice.

The , published in October in the Journal of Geophysical Research–Atmospheres, suggests that existing models underestimate the impact of big waves on ice floes in the Arctic Ocean.

“The loss of sea ice in six days was the biggest change we could find in the historical observations since 1979, and the area of ice lost was 30% greater than the previous record,” said lead author , a research assistant professor of atmospheric sciences at the UW. “The ice models did predict some loss, but only about half of what we saw in the real world.”

Accurate sea ice forecasts are important safety tools for Northern communities, mariners and others operating in Arctic waters. The accuracy of forecasts in the Arctic Ocean also has broader effects.

“The skill of a weather forecast in the Arctic affects the skill of weather forecasts in other places,” Blanchard-Wrigglesworth said.

The January 2022 cyclone had the lowest pressure center estimated since satellite records began in 1979 above 70 degrees north. It was an extreme version of a typical winter storm. Climate change doesn’t appear responsible for the cyclone: The researchers didn’t find a trend in the strength of intense Arctic cyclones since 1979, and sea ice area was close to the historical normal for that region before the storm hit.

Waves travel through sea ice in the Arctic Ocean, as seen from a ship in October 2015. Credit: Ed Blanchard-Wrigglesworth/91Ě˝»¨

During the storm, record winds howled over the Arctic Ocean. The waves grew to 8 meters (26 feet) tall in open water and remained surprisingly strong as they traveled through the sea ice. The ice heaved 2 meters (6 feet) up and down near the edge of the pack, and NASA’s ICESat-2 satellite shows that the waves reached as far as 100 kilometers (60 miles) toward the center of the ice pack.

Six days after the storm struck, the sea ice had thinned significantly in the affected waters north of Norway and Russia, in places losing more than half a meter (about 1.5 feet) of thickness.

“It was a monster storm, and the sea ice got pummeled. And the sea ice models didn’t predict that loss, which suggests there are ways we could improve the model physics,” said second author , a research assistant professor at the University of Alaska Fairbanks. She begins a research position at the 91Ě˝»¨Applied Physics Laboratory in the new year.

The new analysis shows that the atmospheric heat from the storm had a small effect, meaning some other mechanism was to blame for the ice loss. Possibilities, Blanchard-Wrigglesworth suggests, include sea ice that was thinner before the storm hit than models had estimated; that the storm’s waves broke up ice floes more forcefully than models predicted as they penetrated deep into the ice pack; or that waves churned up deeper, warmer water and brought it into contact with the sea ice, melting the ice from below.

The unexpected ice loss, despite an accurate storm forecast, suggests that this is an area where models could improve. The researchers hope to monitor future storms to pinpoint exactly what led to the dramatic sea ice loss, potentially by placing sensors in the path of a future approaching storm.

While this storm doesn’t appear to be linked to climate change, the increase of open water as sea ice melts is allowing for larger waves that are eroding Arctic coastlines. Those waves, researchers said, could also affect the remaining sea ice pack.

“Going into the future, this is something to keep in mind, that these extreme events might produce these episodes of huge sea ice loss,” Blanchard-Wrigglesworth said.

Other co-authors are at NASA, at NASA and the University of Maryland and at the University of Auckland and Brown University. The research was funded by NASA, the U.S. Navy’s Office of Naval Research and Schmidt Futures.

For more information, contact Blanchard-Wrigglesworth at ed@atmos.uw.edu or Webster at mwebster3@alaska.edu.

Grants: NASA: 80NSSC20K0922, 80NSSC20K0959, ONR-DRI: N00014-21-1-2490

91Ě˝»¨ polar scientists are on Alaska’s North Slope this week for the 2016 Barrow Sea Ice Camp. Supported by the National Science Foundation, the event brings together U.S.-based sea ice observers, satellite experts and modelers at various career stages to collect data and discuss issues related to measuring and modeling sea ice. The goal is to integrate the research community in order to better observe and understand the changes in Arctic sea ice.

Check out the group’s , written by a who’s taking his first trip into the field, or follow updates on . The group is based just north of Barrow from May 26 to June 2, in the northernmost point in the U.S.

91Ě˝»¨participants include , a 91Ě˝»¨professor of atmospheric sciences, , an oceanographer at the 91Ě˝»¨Applied Physics Laboratory, , a physicist at the Applied Physics Laboratory, , a 91Ě˝»¨graduate who is now a research assistant at APL, 91Ě˝»¨atmospheric sciences postdoctoral researchers and , and , an anthropology student who has a visiting appointment at APL.

From research stations drifting on ice floes to high-tech aircraft radar, scientists have been tracking the depth of snow that accumulates on Arctic sea ice for almost a century. Now that people are more concerned than ever about what is happening at the poles, research led by the 91Ě˝»¨ and NASA confirms that snow has thinned significantly in the Arctic, particularly on sea ice in western waters near Alaska.

A , now online in the Journal of Geophysical Research: Oceans, combines data collected by ice buoys and NASA aircraft with historic data from ice floes staffed by Soviet scientists from the late 1950s through the early 1990s to track changes over decades.

Historically, Soviets on drifting sea ice used meter sticks and handwritten logs to record snow depth. Today, researchers on the ground use an automated probe similar to a ski pole to verify the accuracy of airborne measurements.

“When you stab it into the ground, the basket move up, and it records the distance between the magnet and the end of the probe,” said first author , a 91Ě˝»¨graduate student in oceanography. “You can take a lot of measurements very quickly. It’s a pretty big difference from the Soviet field stations.”

Webster verified the accuracy of airborne data taken during a March 15, 2012 NASA flight over the sea ice near Barrow, Alaska. The following day Webster followed the same track in minus 30-degree temperatures while stabbing through the snow every two to three steps.

The authors compared data from NASA airborne surveys, collected between 2009 and 2013, with U.S. Army Corps of Engineers buoys frozen into the sea ice, and earlier data from Soviet drifting ice stations in 1937 and from 1954 through 1991. Results showed that snowpack has thinned from 14 inches to 9 inches (35 cm to 22 cm) in the western Arctic, and from 13 inches to 6 inches (33 cm to 14.5 cm) in the Beaufort and Chukchi seas, west and north of Alaska.

That’s a decline in the western Arctic of about a third, and snowpack in the Beaufort and Chukchi seas less than half as thick in spring in recent years compared to the average Soviet-era records for that time of year.

“Knowing exactly the error between the airborne and the ground measurements, we’re able to say with confidence, Yes, the snow is decreasing in the Beaufort and Chukchi seas,” said co-author , an oceanographer at the UW’s Applied Physics Laboratory.

The authors speculate the reason for the thinner snow, especially in the Beaufort and Chukchi seas, may be that the surface freeze-up is happening later in the fall so the year’s heaviest snowfalls, in September and October, mostly fall into the open ocean.

What thinner snow will mean for the ice is not certain. Deeper snow actually shields ice from cold air, so a thinner blanket may allow the ice to grow thicker during the winter. On the other hand, thinner snow cover may allow the ice to melt earlier in the springtime.

Thinner snow has other effects, Webster said, for animals that use the snow to make dens, and for low-light microscopic plants that grow underneath the sea ice and form the base of the Arctic food web.

The new results support a 15-year-old UW-led study in which Russian and American scientists first analyzed the historic Arctic Ocean snow measurements. That detected a slight decline in spring snow depth that the authors believed, even then, was due to a shorter ice-covered season.

“This confirms and extends the results of that earlier work, showing that we continue to see thinning snow on the Arctic sea ice,” said Rigor, who was also a co-author on the earlier paper.

The recent fieldwork was part of NASA’s Operation program, which is using aircraft to track changes while NASA prepares to launch a new ice-monitoring satellite in 2017. The team conducted in spring 2012 as part of a larger program to monitor changes in the Arctic.

The research was supported by NASA and the U.S. Interagency Arctic Buoy Program. Co-authors are Son Nghiem at NASA’s Jet Propulsion Laboratory, Nathan Kurtz at NASA’s Goddard Space Flight Center, Sinead Farrell at the University of Maryland, Don Perovich at the federal Cold Regions Research and Engineering Laboratory and Matthew Sturm at the University of Alaska Fairbanks.

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For more information, contact Webster at melindaw@uw.edu and Rigor at 206-685-2571 or ignatius@apl.washington.edu.

More images are available at  www.flickr.com/uwnews.