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Iceberg breaking off
Petermann glacier in Greenland

Greenland glacier gives birth to
giant iceberg

9 August
2010
Envisat has been observing a rare event in the Arctic
since early August - a giant iceberg breaking off the Petermann
glacier in North-West Greenland.

The Petermann glacier
is one of the largest glaciers connecting the Greenland inland ice
sheet with the Arctic Ocean. Upon reaching the sea, a number of
these large outlet glaciers extend into the water with a floating
'ice tongue'.

The ice tongue of the Petermann glacier was the largest in
Greenland, with an extension of about 70 km until early August. This
tide-water glacier regularly advances towards the ocean at about 1
km per year. During the previous months, satellite images revealed
that several cracks had appeared on the glacier surface, suggesting
to scientists that a break-up event was imminent.

MERIS image after
iceberg calving

In the Envisat
radar image taken on 3 August, the ice tongue was still intact but,
on 4 August, a large part of the floating ice tongue was separated
from the glacier, giving birth to what is currently the largest
iceberg in the northern hemisphere. Such a process of detachment,
called 'calving', occurs regularly on the Petermann glacier, with
smaller calving events in summer 2008 and 2009. However large
calving events are rare, with the last such significant event being
documented in 1991 by ESA’s ERS-1 satellite.

The animation above was created by combining three Envisat
Advanced Synthetic Aperture Radar (ASAR) acquisitions (31 July, 4
August and 7 August 2010) taken over the same area. The breaking of
the glacier tongue and the movement of the iceberg can be clearly
seen in this sequence.

Petermann glacier as
seen by ERS-1 in August 1991

The detached iceberg is now about 30
km by 14 km in size with an area of about 245 sq km. It is floating
away from Petermann glacier and will enter into the Nares Strait,
which separates Greenland from the Ellesmere Island in Canada.

The Nares Strait connects the Lincoln Sea and Arctic Ocean with
the Baffin Bay. The strait is usually navigable by icebreakers
during August/September, when sea ice extent is at its minimum after
the summer melt period. Envisat ASAR images will be used in the
coming days to monitor the movement of the giant iceberg in support
of icebreaker navigation.

The radar imaging system used by Envisat and other satellites is
particularly suited to observe polar areas, as it can acquire images
through cloud or fog, and night and day.

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Related news
Ellesmere Island
and Greenland

Related missions
Envisat

Related links
Polar ViewGreenland sea ice chartsEvent
report by NERSC

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