Warmer climate – fewer polar low-pressure systems to hit Norway

Severe storms along the Norwegian coastline and in the Norwegian Sea are often caused by polar low-pressure systems. Roughly half of all such storms have their origin in low-pressure systems formed above the sea ice covering the Arctic.

Each winter, an average of 12 polar low-pressure systems develop above the marine areas off northern Norway. These systems can move as far south as the UK.

Photo: Erik Kolstad What project researchers saw as they flew over a polar low-pressure system at an altitude of 10 000 metres. (Photo: Erik Kolstad)

Difficult to forecast

Meteorologists can predict other powerful low-pressure systems that are preceded by strong winds days in advance. But there are few early indications of the formation of polar low-pressure systems, which often develop so suddenly that ships’ crews are caught unaware, causing many shipwrecks. Both at sea and along the coastline, polar low-pressure systems often bring major snowfall as well.

In recent years, however, Arctic sea ice cover has declined, and a warming climate may exacerbate this even more. This could lead to fewer polar low-pressure systems – and fewer gale-force winds, storms and hurricanes in the northern areas.

Storms farther north

In the research project The Effect of Climate Change on Arctic High-Impact Weather Events (ArcChange), scientists studied relationships between climate change and polar low-pressure systems. The project received funding from the Research Council of Norway’s Large-scale Programme on Climate Change and its Impacts in Norway (NORKLIMA).

“We believe the frequency of polar low-pressure systems heading toward Norway will drop. As the extent of sea ice declines in the Arctic, the low-pressure systems should move farther north, missing the Norwegian mainland more. Svalbard, however, may be hit by polar low-pressure systems in the future,” explains Researcher Øyvind Sætra of the Norwegian Meteorological Institute.

Photo: ArcChange A polar low-pressure system seen from the ground. (Photo: ArcChange)

Arctic cyclones

Polar low-pressure systems form when extremely cold, dry Arctic air is carried from ice-covered polar regions and across warmer ocean surfaces. The temperature gradient between the air and water can reach up to 20°C – a temperature shock that creates atmospheric chaos and forms an Arctic cyclone, similar to but smaller than its tropical cousin.

There are forces constantly at work to equalise the difference in temperature between water and air. Vast amounts of energy escape the ocean in the form of heat within water vapor – enough, in fact, to power a cyclone.

Energy from the ocean

The ArcChange project has given researchers a whole new level of understanding about how the ocean supplies the energy for polar low-pressure systems. Knowledge about the dynamics of heat energy transfer from marine waters to the atmosphere is vital to international climate research.

During the project, researchers isolated the various physical processes of a polar low-pressure system. This has led to a better understanding of the role of factors such as waves and wind in the development of a cyclone.

Photo: Wikimedia Commons Notice the cyclone shape as a polar low-pressure system hits the coast of Finnmark, Norway’s northernmost county. At the top of the photo, the southern tip of Svalbard is visible. (Photo: Wikimedia Commons)

Wind is to blame

By dropping a total of 147 sondes (atmospheric sensors) into a cyclone from an altitude of 10 000 metres, the researchers were able to map the entire two-day progression of a polar low-pressure system. The team created a three-dimensional depiction of the pressure system; this data could prove valuable in future research.

“A common hypothesis,” says Dr Sætra, “has held that preceding the formation of a polar low-pressure system, the air down near the marine surface amasses huge amounts of what we geophysicists call CAPE (convectively available potential energy). But we found no such CAPE when we released our sondes to float down through the storm, so we have now concluded that it must be the wind that whips up the entire energy transport from the ocean to the air.”

Warmer ocean temperatures not a factor

Until now, many climatologists have believed that global warming and higher ocean temperatures would cause the transfer of more energy from the water to the atmosphere, stirring up higher winds and more storms.

The ArcChange researchers believe that higher marine temperatures have practically no impact on polar low-pressure systems, because in a warmer climate the atmosphere is warmed more quickly than the water. Thus the temperature gradient between the ocean and atmosphere would be more likely to decrease rather than increase.

The ArcChange project
The ArcChange project was a collaboration between scientists from the Norwegian Meteorological Institute, the Department of Physics and Technology at the University of Bergen, and the Bjerknes Centre for Climate Research in Bergen.

 

 

 

Related news

Latest news

Jotne Subsea Gas Lift for Balder Field

In April 2015, Jotne E&P was awarded an EPC contract to build the subsea gas lift manifold for Exxon Mobil on the Balder Field.

Jotne Awarded Contract for Subsea Protection Structure

In January 2016, Jotne E&P was awarded a contract for the delivery of a subsea protection structure and GRP cover for a Xmas tree at Balder field. The contract was awarded by Ocean Installer.

UiB and CMR in high-tech collaboration

Students from UiB last month joined an experiment with an ultra-high-speed camera. This was a part of the troubleshooting of the Field Kelvin Probe currently under development.

Hatteland Display at International Workboat Show 2016

Hatteland Display are highlighting its diverse portfolio of maritime displays and panel computers on its booth (#1658) at the International Workboat Show 2016 (IWBS 2016) this week.

Servogear Announces Upcoming Events

Servogear announces a busy end of November, beginning of December. They will be participating at important international exhibitions.

Teamtec and ANDRITZ Cooperation

ANDRITZ and TeamTec have signed a cooperation agreement for worldwide marketing of the SeaSOx exhaust gas cleaning system for the maritime industry. 

Export Credit Norway looking for Norway's Best Exporter

Export Credit Norway  has now opened the nomination process for the 2017 Export Award, searching the Norwegian exporter of the year. 

Global Economic Outlook

7 December, Oslo Chamber of Commerce invites to a session with insightful updates on the Norwegian and international economy.

Rebuilding for Hydrogen

M/Y “Che Guevara”, previously owned by Gaddafi, will be converted to run on hydrogen. Greenstat will lead the project and are seeking partners.