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Earth from Space – Petermann Ice Island

Petermann Ice Island seen from space

The huge Petermann Ice Island broke free from Greenland's Petermann Glacier in August 2010.

AFTER  MORE THAN A YEAR and several thousand kilometres of sailing the seas, Petermann Ice Island is still drifting in the North Atlantic off the shores of Newfoundland, Canada.

Once a hunk of ice fives times the size of Manhattan Island, the ice island has splintered several times since it dropped off the edge of Greenland’s Petermann Glacier.

Yet still it behaves a bit like the massive ice sheet it left 14 months ago.

Astronauts on the International Space Station used a digital camera to capture this view of Petermann Ice Island A, fragment 2, off of the northeast coast of Newfoundland on August 29, 2011.

Spanning roughly 4 kilometres by 3.5 kilometres, the ice island is covered with melt ponds and streams, much as the surface of Greenland looks in mid-summer.

As ice melts on top of the Greenland ice sheet, the melt water forms streams and pools in the depressions on the ice surface. Drawn downslope by gravity—much like streams on a mountainside—water also runs toward the edges of the ice. In some cases, it cracks through it and rushes to the bottom.

Such processes appear to be at work on the ice island as well.

August 2011 was a busy month in the life of the ice island, according to the Canadian Ice Service. On August 7, it became grounded on a shoal or shallow seafloor off of St. Anthony, Newfoundland, where it sat for 11 days.

By August 18, the ice island broke free and began drifting again, only to split into two large pieces about five days later. The Ice Service last reported on it on August 25.

See the full-size image of the Petermann Ice Island here.

Astronaut photograph provided by the ISS Crew Earth Observations experiment and Image Science & Analysis Laboratory, Johnson Space Centre. Text adapted from information issued by Mike Carlowicz.

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Greenland’s changing landscape

Petermann Glacier and iceberg

A massive iceberg broke from the Petermann Glacier in Greenland on August 5.

On August 5, 2010, the unassuming Petermann Glacier on Greenland’s northwestern coast hit the world’s headlines when a huge ice island “calved” from it and started drifting down a fjord.

Eleven days later, the island was continuing its slow migration down the fjord. The Advanced Land Imager (ALI) on NASA’s Earth Observing-1 (EO-1) satellite captured a natural-colour image (above) on August 16, 2010.

Although slivers of ice had loosened around its edges, the ice island had largely retained its original shape. The island, which had rotated counterclockwise since the calving, also retained the crevassed structure of the Petermann Glacier; both the glacier and the ice island sport rippled surfaces.

Thin longitudinal cracks appear on the ice island surface, and wider lateral cracks push in from the island’s sides. An uneven line of pools, medium blue in colour, runs down the length of the ice island.

Along the glacier’s new front, some smaller icebergs appear to have broken free, and ice fragments litter the water surface between the ice island and the glacier. Also visible in the image are multiple small glaciers that feed the Petermann, flowing down to the massive glacier from the northeastern side of the fjord.

See the full-size, high-resolution image here (4MB, new window).

Phytoplankton bloom off the east coast of Greenland.

Satellite image of a phytoplankton bloom off the east coast of Greenland.

Meanwhile, on Greenland’s eastern seaboard, the stark black and white landscape of provides a fine palette for the burst of colour created by a large phytoplankton bloom, spotted by the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra  satellite on August 7, 2010.

The bloom blends shades of milky blue, turquoise, and green, created by different species of phytoplankton growing in the cold, nutrient-rich waters. Likely shaped by the East Greenland Current, the bloom extends along the southeast coast of Greenland.

The full length of the bloom is visible in the large image (0.7MB, new window), which shows a broader area.

The phytoplankton bloom is not the only source of colour in the scene. The brilliant white of the ice sheet fades to grey in places along the shore where old ice is exposed. Tinted faintly brown like the craggy brown rocks that channel them, glaciers seep from the ice sheet into fjords, rivers of ice draining the great ice sheet. The glaciers give way to green-blue water, milky with the fine sediment created as the ice grinds over rock.

These waters and the deep black-blue waters of the Atlantic Ocean are dotted with icebergs. No more than tiny white specks at this scale, the icebergs resemble tiny grains of salt floating on the water’s surface.

NASA images courtesy Jeff Schmaltz, MODIS Rapid Response Team at NASA GSFC; and Jesse Allen and Robert Simmon, using EO-1 ALI data provided courtesy of the NASA EO-1 team and the United States Geological Survey. Text adapted from information issued by Michon Scott and Holli Riebeek.

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Greenland’s swirling ice

Swirls of ice along Greenland's coast.

Like foam on a latte, seasonal swirls of ice congregate on Greenland's coast.

Various types of sea ice congregated along the east coast of Greenland in late March 2010. The Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Aqua satellite captured this relatively cloud-free natural-colour image on March 27, 2010. In the upper left quadrant of the image is the Greenland coast. Open ocean predominates in the lower right quadrant.

Closest to land, land-fast sea ice clings to the shore, impervious to ocean currents. This ice is often held in place by shallow ocean bottoms or continental shelves. Farther away from land, however, the situation changes as ocean currents play a greater role in moving and shaping ice.

The East Greenland Current flows southward from the Arctic along the island’s eastern coast, carrying sea ice with it. Ice carried by this current occurs in large, thick pieces, and the ice in this swath along the Greenland coast almost certainly originated elsewhere.

The large white circular shapes in this image are pieces of multiyear ice carried to this location by the East Greenland Current. Just as the relentless movement of water in rivers and streams can smooth the jagged edges of rocks over time, ocean currents can smooth ice fragments into round shapes.

Even farther out to sea than the large fragments of multiyear ice are much smaller pieces of ice—so small that they are at the mercy of even small surface currents. Collectively these tiny ice fragments form delicate swirls of ice that resemble foam on latte.

NASA image by Jeff Schmaltz, MODIS Rapid Response Team at NASA GSFC. Text adapted from information issued by Michon Scott based on image interpretation by Florence Fetterer, National Snow and Ice Data Centre.