Giant Berg enters Nares Straight

[marchesarosa]

Image of the week



Earth from Space: Giant iceberg enters Nares Strait




3 September 2010
ESA's Envisat satellite has been tracking the progression of the giant iceberg that calved from Greenland's Petermann glacier on 4 August 2010. This animation shows that the iceberg, the largest in the northern hemisphere, is now entering Nares Strait – a stretch of water that connects the Lincoln Sea and Arctic Ocean with Baffin Bay.

The Petermann glacier in northern Greenland is one of the largest of the country's glaciers – and until August it had a 70 km tongue of floating ice extending out into the sea. The glacier regularly advances towards the sea at about 1 km per year.
Earlier this year, satellite images revealed that several cracks had appeared. Envisat radar images showed that the ice tongue was still intact on 3 August but, on 4 August, a huge chunk had detached.

Calvings from the Petermann glacier are quite common, but one of this magnitude is rare. Less significant events took place in 2001, in 2008 when a 27 sq km iceberg made its way south to Davis Strait, and in 2009.

This iceberg is about 30 km long and 15 km wide at its foot and almost 7 km wide at its head, covering an area of around 245 sq km. By 22 August this giant mass of ice had been carried about 22 km from its birth place.

On 1 September imagery showed that the iceberg had travelled almost another 6 km from the edge of the glacier and rotated westward (about 39°), just tipping into Nares Strait. The animation also shows that the iceberg hit a small island, which may delay further progression for a short while and may also cause the iceberg to break.

It is expected that the iceberg will soon be fully in Nares Strait, but its course depends on winds blowing off the glacier and currents in the strait, as well as sea ice that could block its path.

The animation was generated from 21 Envisat Advanced Synthetic Aperture Radar (ASAR) Wide Swath Mode (spatial resolution 150 m × 150 m) and three ASAR Image Mode (spatial resolution 30 m × 30 m) images.

[lazarus]

I believe the current melt season is just about over. Do you know it this strait freezes over? It might trap it until next year.

[marchesarosa]

As interesting as the movement of the berg is, just as informative is the constantly changing disposition of the OTHER ice in the satellite pics over the month.

The Nares Straight is one of the exits from the Arctic Ocean where ice can be "flushed out" in the summer when the prevailing winds are from the north.

[travis]

Sept 9, 2010 1:53:48 GMT 1 lazarus said:

I believe the current melt season is just about over. Do you know it this strait freezes over? It might trap it until next year.

The waters of the Nares Strait do freeze in the winter, but like sea ice in the Greenland Sea, the ice is constantly being pushed south by currents and the prevailing winds, getting replaced by new ice as well as thicker multi-year ice that pushes in from the Arctic Basin. If it weren't for the sheer size of the ice island in question, I'd say that it would drift south out into Baffin Bay this winter. However in this particular case, it may get stuck up there until next spring unless it breaks up into smaller pieces. Time will tell.

[lazarus]

Here is a interesting report from a geophysicist from the University of St Andrews, UK, Richard Bates, who expected it to happen and installed time-lapse cameras atop the 900-metre-high cliffs and placed eight Global Positioning System (GPS) units along the glacier's centre line to monitor the event;
www.nature.com/news/2010/100909/full/news.2010.459.html?s=news_rss&utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+news%2Frss%2Fmost_recent+%28NatureNews+-+Most+recent+articles%29&utm_content=Google+Reader