Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Envisat shows behemoth B-15A iceberg breaking up

08.11.2005


After five years of being the world’s largest free-floating object, the B-15A iceberg has finally broken up off Antarctica’s Cape Adare.



ESA’s Envisat satellite’s Advanced Synthetic Aperture Radar (ASAR) is sensitive to ice, and has been tracking the movement of the drifting ice object since the beginning of this year. Its latest imagery reveals the bottle-shaped iceberg split into nine knife-shaped icebergs and a myriad of smaller pieces on 27-28 October, the largest being formed by fractures along the long axis of the original single iceberg.

Measuring – until last week - around 115 kilometres in length with an area exceeding 2500 square kilometres, the iceberg had apparently run aground off Cape Adare, the northernmost corner of the Victoria Land Coast. This stranding appears to have led to flexing and straining which resulted in the break-up.


"The long knife-shaped pieces suggest the iceberg has split along existing lines of weakness within the iceberg," says Mark Drinkwater of ESA’s Ocean and Ice Unit. "These would have been pre-existing crevasses in the ice shelf."

These new icebergs, named by the US National Oceanic and Atmospheric Administration (NOAA) National Ice Center, will retain their parent’s title: the three largest island-sized pieces have been called B-15M, B-15N and B-15P.

B-15A was the largest remaining section of the even larger B-15 iceberg that calved from the nearby Ross Ice Shelf in March 2000 before breaking up into smaller sections.

Since then its B-15A section drifted into McMurdo Sound, where its presence blocked ocean currents and led to a build-up of sea ice that decimated local penguin colonies, deprived of open waters for feeding. During the spring of this year prevailing currents took B-15A slowly past the Drygalski ice tongue. A full-fledged collision failed to take place, but a glancing blow broke the end off Drygalski in mid-April.

The iceberg sailed on to have a less-destructive close encounter with the Aviator Glacier ice tongue at Lady Newnes Bay before becoming stranded off Cape Adare in mid-October.

Radar monitoring of Antarctic ice

ASAR is extremely useful for tracking changes in polar ice. ASAR can peer through the thickest polar clouds and work through local day and night. And because it measures surface texture, the instrument is also extremely sensitive to different types of ice – so the radar image clearly delineates the older, rougher surface of icebergs from surrounding sea ice, while optical sensors simply show a continuity of snow-covered ice.

Envisat’s ASAR instrument monitors Antarctica in two different modes: Global Monitoring Mode (GMM) provides 400-kilometre swath one-kilometre resolution images, enabling rapid mosaicking of the whole of Antarctica to monitor changes in sea ice extent, ice shelves and iceberg movement.

Wide Swath Mode (WSM) possesses the same swath but with 150-metre resolution for a detailed view of areas of particular interest.

ASAR GMM images are routinely provided to a variety of users including the National Ice Center, responsible for tracking icebergs worldwide.

Mariangela D’Acunto | alfa
Further information:
http://www.esa.int/esaEO/SEMCYK638FE_planet_0.html

More articles from Earth Sciences:

nachricht Global study of world's beaches shows threat to protected areas
19.07.2018 | NASA/Goddard Space Flight Center

nachricht NSF-supported researchers to present new results on hurricanes and other extreme events
19.07.2018 | National Science Foundation

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: First evidence on the source of extragalactic particles

For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.

To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...

Im Focus: Magnetic vortices: Two independent magnetic skyrmion phases discovered in a single material

For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.

Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...

Im Focus: Breaking the bond: To take part or not?

Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.

A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...

Im Focus: New 2D Spectroscopy Methods

Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.

"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....

Im Focus: Chemical reactions in the light of ultrashort X-ray pulses from free-electron lasers

Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.

Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Leading experts in Diabetes, Metabolism and Biomedical Engineering discuss Precision Medicine

13.07.2018 | Event News

Conference on Laser Polishing – LaP: Fine Tuning for Surfaces

12.07.2018 | Event News

11th European Wood-based Panel Symposium 2018: Meeting point for the wood-based materials industry

03.07.2018 | Event News

 
Latest News

Global study of world's beaches shows threat to protected areas

19.07.2018 | Earth Sciences

New creepy, crawly search and rescue robot developed at Ben-Gurion U

19.07.2018 | Power and Electrical Engineering

Metal too 'gummy' to cut? Draw on it with a Sharpie or glue stick, science says

19.07.2018 | Materials Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>