Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Atmospheric wave linked to sea ice flow near Greenland, study finds

29.08.2002


A NASA researcher finds that the amount of sea ice that moves between Greenland and Spitsbergen, a group of islands north of Norway, is dependent upon a "wave" of atmospheric pressure at sea level. By being able to estimate how much sea ice is exported through this region, called Fram Strait, scientists may develop further insights into how the ice impacts global climate.



This export of sea ice helps control the thermohaline circulation, a deep water ocean conveyor belt that moves warm, salty water poleward and cold, fresh water toward the equator. The thermohaline circulation is one of the primary mechanisms that maintains the global heat balance.

Don Cavalieri, a researcher at NASA’s Goddard Space Flight Center in Greenbelt, Md., discovered a link between the transport of sea ice through this region and the position or phase of the longest sea level pressure wave circling the Earth at polar latitudes.


Until now, scientists have had inconsistent results when trying to identify the mechanism behind this transport of sea ice. The North Atlantic Oscillation, in particular, was unable to explain the changes in sea ice transport through Fram Strait.

"The significance of this work is the connection between the phase of the longest atmospheric wave called ’wave 1’ in sea level pressure and long-term Arctic Ocean and sea ice variability," said Cavalieri.

Sea level pressure is made up of high and low pressure systems as any weather map will show. The large-scale semi-permanent highs and lows define the longest pressure waves which are called planetary waves because they extend thousands of miles and circle the world. The longest wave, called wave 1, is made up of one ridge (high pressure) and one trough (low pressure). It turns out that wave 1 is the dominant pattern at polar latitudes. Because these planetary waves are so dominant in wintertime atmospheric circulation their amplitudes (strength) and phases (position) provide useful information on large-scale wind patterns and thus on sea ice transport.

The Icelandic Low is the primary weather system in the North Atlantic. At times this low pressure system extends northeastward into the Barents Sea. When this happens a secondary low pressure system may develop in the Barents Sea region. It is the counterclockwise circulation around this secondary low pressure system in the Barents Sea that drives sea ice through the Fram Strait. Whenever this secondary low pressure system exists, wave 1 shifts eastward and is said to be in its eastward phase, as opposed to a westward phase.

When wave 1 is in its westward mode, the Icelandic Low is more intense and localized, no longer extending to the Barents Sea. Because of the position of the Low relative to the Strait, the winds are more westerly and less ice is forced southward through Fram Strait.

Variations in the phase of wave 1 between these two extreme modes also seem to control the cycle of Arctic Ocean circulation which reverses from clockwise to counterclockwise (or anticyclonic to cyclonic, respectively) every 6 or 7 years.

Cavalieri used simulations for the 40 year period (1958-1997) from two computer models to obtain a record of the volume of sea ice that moved through Fram Strait. The two models each showed a similar correlation between the eastward phase of wave 1 and movement of sea ice through the strait, with the exception of two anomalous years between 1966 and 1967. When those years were removed, one ice-ocean model, using monthly surface wind and air temperature data, found that the wave 1 eastward phase explained 70 percent of Arctic ice export through Fram Strait, while the other model, which used daily surface wind and air temperature data, accounted for 60 percent of the sea ice export.

Cavalieri also used Northern Hemisphere monthly sea level pressure grids to obtain phase and amplitude information for wave 1.

The paper appeared in a recent issue of Geophysical Research Letters.


The study was funded by NASA’s Cryospheric Sciences Research Program.

Krishna Ramanujan | EurekAlert!
Further information:
http://www.gsfc.nasa.gov/topstory/20020807seaice.html

More articles from Earth Sciences:

nachricht Predicting unpredictability: Information theory offers new way to read ice cores
07.12.2016 | Santa Fe Institute

nachricht Sea ice hit record lows in November
07.12.2016 | University of Colorado at Boulder

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Significantly more productivity in USP lasers

In recent years, lasers with ultrashort pulses (USP) down to the femtosecond range have become established on an industrial scale. They could advance some applications with the much-lauded “cold ablation” – if that meant they would then achieve more throughput. A new generation of process engineering that will address this issue in particular will be discussed at the “4th UKP Workshop – Ultrafast Laser Technology” in April 2017.

Even back in the 1990s, scientists were comparing materials processing with nanosecond, picosecond and femtosesecond pulses. The result was surprising:...

Im Focus: Shape matters when light meets atom

Mapping the interaction of a single atom with a single photon may inform design of quantum devices

Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what...

Im Focus: Novel silicon etching technique crafts 3-D gradient refractive index micro-optics

A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.

Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...

Im Focus: Quantum Particles Form Droplets

In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.

“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...

Im Focus: MADMAX: Max Planck Institute for Physics takes up axion research

The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.

The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ICTM Conference 2017: Production technology for turbomachine manufacturing of the future

16.11.2016 | Event News

Innovation Day Laser Technology – Laser Additive Manufacturing

01.11.2016 | Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

 
Latest News

NTU scientists build new ultrasound device using 3-D printing technology

07.12.2016 | Health and Medicine

The balancing act: An enzyme that links endocytosis to membrane recycling

07.12.2016 | Life Sciences

How to turn white fat brown

07.12.2016 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>