Arctic cyclones

[vox_mundi]

Although they are referenced anecdotaly in various threads, Arctic cyclones do not appear to have their own thread like hurricanes. If this thread is redundant feel free to move or delete.

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Cyclones In the Arctic Are Forming More Often and Getting Stronger: Study Suggests
https://phys.org/news/2023-10-cyclones-arctic-stronger.html



A team of Earth scientists from North Carolina State University, the University of Alaska Fairbanks, North Carolina A&T State University, and Sandia National Laboratories has found evidence that suggests cyclones have become more common over the past half-century and have also become stronger.

In their paper published in the journal Communications Earth & Environment, the group describes how they gathered resource data from a variety of sites covering decades of environmental research in the Arctic and what they learned about cyclones in the region.

Prior research has shown that temperatures in the Arctic are rising faster than anywhere else on Earth. Such changes have led to ice forming later and melting earlier each year; some scientists have predicted that there may be ice-free summers by the end of this decade. In this new effort, the research team focused their attention on Arctic cyclones. This came on the heels of the strongest known cyclone to ever strike the Arctic region last year. With wind speeds up to 67mph, the storm generated massive waves that broke up a lot of the winter ice.

To find out if such storms are becoming more prevalent, the research group gained access to a large number of data sets that hold climate information about the Arctic, going back to the 1950s. They then made comparisons of cyclones that have occurred over the past seventy years.

The researchers found what they describe as a clear association between rising temperatures and cyclone formation in the Arctic. They also found that changes in temperature gradients are playing a role in the size and strength of the cyclones that form, and noted that changes in the jet stream are likely linked to the increase in numbers of Arctic cyclones, particularly in the winter. Additionally, vortexes of polar air in the troposphere have been strengthening, leading to more cyclones in the summer.



The team concludes by observing that as more cyclones of larger size strike the Arctic, more sea ice breaks up, speeding up the process of climate change in the region.

Xiangdong Zhang et al, Arctic cyclones have become more intense and longer-lived over the past seven decades, Communications Earth & Environment (2023)
https://www.nature.com/articles/s43247-023-01003-0

... There has been a long-term shift of the maximum cyclone counts from weaker to stronger cyclones and a pronounced lengthening of the duration of strong cyclones. Spatial analysis shows increased strong cyclone frequency over the Arctic, driven by enhanced lower troposphere baroclinicity, amplified winter jet stream waves over the subpolar North Atlantic, and a strengthened summer tropospheric vortex over the central Arctic. The stratospheric vortex has also intensified the tropospheric waves and vortex with distinct dynamics between winter and summer. Recently enhanced baroclinicity over large areas of the Arctic and midlatitudes suggests more complicated atmospheric dynamics than what is hypothesized with Arctic-amplification-induced decrease in meridional temperature gradients.

[binntho]

Good initiative. I am surprised to learn that the strongest ever Arctic cyclone was last year, with winds up to 67 mph (108 km/h or 30 m/s).

Anectdotal evidence from the Beaufort was that sustained 20 m/s winds were enough to clear ice totally away overnight - but can't remember the details such as time of year and ice thickness.

[vox_mundi]

cross-posted from:  https://forum.arctic-sea-ice.net/index.php/topic,596.msg352522.html#msg352522

Study Shows That Strongest Arctic Cyclone On Record Led to Surprising Loss of Sea Ice
https://phys.org/news/2022-11-strongest-arctic-cyclone-loss-sea.html

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 University of Washington shows that while weather forecasts accurately predicted the storm, ice models seriously underestimated its impact on the region's sea ice.



The study, 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 Ed Blanchard-Wrigglesworth, 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."


Waves travel through sea ice in the Arctic Ocean, seen from a ship in October 2015.

The January 2022 cyclone had the lowest pressure center estimated since satellite records began in 1979 above 70 degrees north (January 24 - 932.2 mb at 79.5°N 20°E.). 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.

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.





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.

Edward Blanchard‐Wrigglesworth et al, Record Arctic Cyclone of January 2022: Characteristics, Impacts, and Predictability, Journal of Geophysical Research: Atmospheres (2022)
https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2022JD037161

... The cyclone had significant impacts on the atmosphere, sea ice and ocean waves. Air temperatures at the surface and aloft peaked over 10°C above climatology over large sections of the Barents/Kara/East Laptev seas, accompanied by extreme surface winds, with 1-hourly values that peaked at 100 km/hr over the north Barents Sea. Surface energy fluxes were also anomalous with respect to climatology, with a mean 6-day net input of energy into the sea ice from the atmosphere of ∼35 W/m2 as estimated using satellite data, dominated by extreme turbulent fluxes, which were the largest for January over 2003–2022. While the SEB values are anomalous, they are smaller than the ∼60 W/m2 estimated for the extreme cyclone of December 2015/January 2016 in the Barents/Kara seas, an event that was dominated by extreme warmth and moisture anomalies (Boisvert et al., 2016). The January 2022 cyclone temperature anomalies were also not record values, but were in the 95% percentile. Surface wind speeds reached record values over a sea-ice covered sector of the Barents Sea, and large ocean waves over 6 m impinged on the sea ice over several days, with significant waves-in-sea-ice of 2 m height detected by satellite altimetry up to 100 km into the sea ice pack.

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See also: https://forum.arctic-sea-ice.net/index.php/topic,3648.msg330257.html#msg330257

https://forum.arctic-sea-ice.net/index.php/topic,3648.msg330259.html#msg330259

https://forum.arctic-sea-ice.net/index.php/topic,3648.msg330476.html#msg330476

https://forum.arctic-sea-ice.net/index.php/topic,3648.msg330589.html#msg330589

https://forum.arctic-sea-ice.net/index.php/topic,3648.msg330735.html#msg330735

https://forum.arctic-sea-ice.net/index.php/topic,3648.msg330744.html#msg330744